WO2003039459A2 - Viral vector production methods and compositions - Google Patents

Abstract

The present invention provides methods of preparing viral vector particles and viral vector particle compositions.

Description

VIRAL VECTOR PRODUCTION METHODS AND COMPOSITIONS

FIELD OF THE INVENTION [0001] This invention pertains to viral vector production methods and compositions.

BACKGROUND OF THE INVENTION [0002] Viral vectors have proven convenient vector systems for investigative and therapeutic gene transfer applications. Due to these advantages, researchers have developed numerous gene therapy applications based upon viral vectors. As such viral vector-based applications move through clinical trials and into approved medical applications, there will be an increasing need for efficient large-scale production of viral vector compositions that are compliant with current good manufacturing practices (cGMP) and suitable for administration to patients.

[0003] Techniques for producing viral vectors and viral vector compositions are known in the art. With respect to adenoviral vectors, for example, several techniques have been developed for culturing adenovirus packaging cells, lysing such cells, and purifying adenoviral vector compositions from such lysates. Examples of such techniques are described in, e.g., U.S. Patents 5,837,520, 6,194,191, 6,168,941, and 6,261,823 and International Patent Applications WO 99/54441 and WO 00/32754. [0004] While the techniques described in the art have proven useful for the production of viral vectors (particular the cell culturing techniques ofthe '941 patent and the purification techniques ofthe '754 application), there remains a need for improved and alternative viral vector compositions and methods of producing the same. The invention provides such compositions and methods. These and other advantages ofthe invention, as well as additional inventive features, will be apparent from the description ofthe invention provided herein.

BRIEF SUMMARY OF THE INVENTION [0005] The present invention provides methods of preparing viral vector particles and viral vector particle compositions. The method ofthe invention includes obtaining a population of viral vector particle producing (packaging) cells, adapting the cells, if necessary, to a suitable culture medium, propagating the cells in the medium and under conditions suitable for production of viral vector particles. The cells are typically harvested from the culture and subjected to lysis, preferably by microfluidization or detergent lysis to form a lysate. The lysate can be subject to one or more clarification steps to remove debris, typically by depth filtration or microfiltration, to obtain a filtered lysate. The filtered lysate typically is subjected to one or more ultrafiltration steps that concentrate the viral vector particle composition or serve as a diafiltration step. The composition desirably is subjected to nuclease digestion, preferably at elevated temperatures (e.g., at about 33-36° C for about 3-5 hours). Additionally, further nucleic acid removal can be accomplished by ultrafiltration in a high salt buffer, organic solvent buffer, or a combination thereof. Additional filtration steps can remove proteins (through high salt filtration) or lipids (through organic solvent and/or derivatized filter filtration). The completely filtered composition can be further purified by one or more chromatography steps, which preferably will include at least one anion exchange chromatography step and at least one size exclusion chromatography step. Hydrophobic interaction chromatography, negative chromatography, series chromatography, and additional ion exchange chromatography steps optionally can further purify the composition. The viral vector particle composition desirably is eluted from the ion exchange chromatography column by a reverse flow, step wise elution. The size exclusion column is desirably packed at a rate such that void space is minimized to optimize purification. At least portions ofthe method are performed in an environmentally isolated ("closed") system, using sterile passageways and (preferably) disposable plastic receptacles mated to devices used in the purification and production process. The method also optionally comprises performing one or more hold steps, of at least about 3 hours, wherein a high proportion of active viral vector particles in the composition is maintained, and wherein the components ofthe system and/or suitability ofthe composition is assessed. The method can ideally be performed using one or more automated programmable monitoring systems, which regulate key parameters in the production process (e.g., the temperature ofthe aforementioned benzon nuclease digestion). [0006] The invention further provides viral vector particle compositions, comprising a significant number and concentration of viral vector particles (e.g., at least about 1 x 10 PU), wherein the composition has a significantly low level of non- viral vector component proteins (e.g., less than about 50 ng of total host cell protein) and a significantly low level of non- viral vector particle encapsidated polynucleotides, particularly polynucleotides of any significant length (e.g., polynucleotides of about 120 ng or less are typically in a concentration of less than about 10 ng in the composition). The invention provides particular methods of producing adenoviral vector particle compositions (particularly replication-deficient recombinant adenoviral vector gene transfer particle compositions), which are preferred. Such compositions are further characterized by a low level of replication-competent adenovirus (RCA), a low level of El -reversion, and significant level of transgene expression, a low PU/FFU level, a high level of active viral vector particles, an acceptable toxicology level, and a low level of host cell proteins indicative of protein contamination, which can be determined by novel assays provided herein. DETAILED DESCRIPTION OF THE INVENTION [0007] The present invention provides viral vector particle compositions and methods of producing the same. The compositions ofthe invention can include, and methods ofthe invention can be practiced, with any suitable type of viral vector particle. A "viral vector particle" is any particle comprising a collection of viral proteins that form a particle with an interior volume, which transfers to a host cell and/or expresses in a host cell genetic information contained in the interior volume. A viral vector particle can be based upon, derived from, or originate from any suitable virus. The viral vector particle can be an unmodified naturally occurring (i.e., "wild-type") virus particle. More typically, the viral vector particle will be a modified viral particle, such as a viral gene transfer vector and/or a synthetic viral vector particle. Desirably, the viral vector particle contains, or is associated with, a nucleotide genome, which preferably is a DNA genome, and most preferably is a double-stranded DNA genome, as such viral genomes are typically easier to manipulate when generating a viral gene transfer vector. Due to the limitations of their genomes, viral vectors with single-stranded RNA genomes are least preferred (although such viral vector particles often still are suitable). The viral vector particle desirably comprises a genome that is transcribed and replicated in the nucleus ofthe host cell, and the mRNAs transcribed therefrom are preferably processed posttranscriptionally and moved to the cytoplasm for translation (thus, mimicking the translation of host genes). Preferably, the viral vector particle's nucleic acid (or portion thereof) does not integrate into the host cell genome. Preferably, though not necessarily, the viral vector particle is derived from, is based on, comprises, or consists of, a virus that normally infects animals, preferably vertebrates, such as mammals and, especially, humans.

[0008] Suitable viral vector particles include, for example, adenoviral vector particles (including any virus of or derived from a virus ofthe adenoviridae), adeno-associated viral vector particles (AAV vector particles) or other parvoviruses and parvoviral vector particles, papillomaviral vector particles, reovirus particles, and viruses of, or viral vector particles derived from, the arenaviridae, bunyaviridae, circoviridae, coronaviridae, filoviridae, flaviviridae, hepadnaviridae, herpesviridae, paramyxoviridae, rhabdoviridae, orthomyxoviridae, poxviridae, retroviridae, togaviridae, birnaviridae, astroviridae, potyviridae, picornaviridae, myoviridae, tectiviridae, nodaviridae, calciviridae, iridoviridae, caulimoviridae, papovaviridae, andphycodnaviridae. The viral vector particle is preferably a non-enveloped viral vector particle. Examples of suitable non-enveloped viral vector particles include adenoviral vector particles, AAV vectors, or viruses of, or viral vector particles derived from, the papillomaviral, parvoviridae, reoviridae, birnaviridae, astroviridae, potyviridae, picornaviridae, myoviridae, tectiviridae, nodaviridae, calciviridae, iridoviridae, caulimoviridae, papovaviridae, anάphycodnaviridae. Examples of such viruses and viral vectors are provided in, e.g., VIROLOGY, B.N. Fields et al., eds., Raven Press, Ltd., New York (3rd ed., 1996 and 4th ed., 2001), ENCYCLOPEDIA OF VIROLOGY, R.G. Webster et al., eds., Academic Press (2nd ed., 1999), FUNDAMENTAL VIROLOGY, Fields et al., eds., Lippincott-Raven (3rd ed., 1995), Levine, "Viruses," Scientific American Library No. 37 (1992), MEDICAL VIROLOGY, D.O. White et al., eds., Academic Press (2nd ed. 1994), INTRODUCTION TO MODERN VIROLOGY, Dimock, NJ. et al, eds., Blackwell Scientific Publications, Ltd. (1994), and other references cited herein. [0009] The basic construction of recombinant viral vectors is well understood in the art. For example, adenoviral vectors can be constructed and/or purified using the methods set forth, for example, in Graham et al., Mol. Biotechol, 33(3), 207-220 (1995), U.S. Patents 5,922,576, 5,965,358 and 6,168,941 and International Patent Applications WO 98/22588, WO 98/56937, WO 99/15686, WO 99/54441, and WO 00/32754. Adeno-associated viral vectors can be constructed and/or purified using the methods set forth, for example, in U.S. Patent 4,797,368 and Laughlin et al., Gene, 23, 65-73 (1983). Similar techniques are known in the art with respect to other viral vectors, particularly with respect to herpes viral vectors (see e.g., Lachman et al., Curr. Opin. Mol. Then, 1(5), 622-32 (1999)), lentiviral vectors, and other retroviral vectors.

[0010] The viral vector particle can be a chimeric viral vector particle. Examples of chimeric viral vector particles are described in, e.g., Reynolds et al., Mol. Med. Today, 5(1), 25-31 (1999), Boursnell et al., Gene, 13, 311-317 (1991), Dobbe et al., Virology, 288(2), 283-94 (2001), Grene et al., AIDS Res. Human. Retroviruses, 13(1), 41-51 (1997), Reimann et al., J. Virol, 70(10), 6922-8 (1996), Li et al, J. Virol, 67(11), 6659-66 (1993), Dong et al., J Virol, 66(12), 7374-82 (1992), and U.S. Patents 5,877,011, 6,183,753, 6,146,643, and 6,025,341.

[0011] Particularly preferred types of viral vector particles include adeno-associated viral vector particles and adenoviral vector particles. Adenoviral vector particles are most preferred. The adenoviral vector particle can be, or be derived from, any suitable type of adenovirus. For instance, an adenovirus particle can be of (or derived from a virus of subgroup A (e.g., serotypes 12, 18, and 31), subgroup B (e.g., serotypes 3, 7, 11, 14, 16, 21, 34, and 35), subgroup C (e.g., serotypes 1, 2, 5, and 6), subgroup D (e.g., serotypes 8, 9, 10, 13, 15, 17, 19, 20, 22-30, 32, 33, 36-39, and 42-47), subgroup E (serotype 4), subgroup F (serotypes 40 and 41), or any other adenoviral serotype. Preferably, the adenoviral vector particle is based on, derived from, or consists of a serotype-2 or serotype-5 adenovirus. In some situations, type 35 adenoviral vector particles (as described in, e.g., International Patent Application WO 01/41814) are desired as gene delivery vehicles, particularly where immune response to the vector is a concern. Other examples of suitable adenoviral vectors, including replication-defective adenoviral vectors, are described in, e.g., International Patent Applications WO 95/34671, WO 97/21826, WO 99/41398, WO 00/00628, U.S. Patents 5,559,099, 5,712,136, 5,731,190, 5,801,030, 5,837,511, 5,846,782, 5,851,806, 5,962,311, 5,965,541, 5,981,225, 5,994,106, 5,965,541, 5,994,106, 6,020,191, 6,113,913, and 6,225,113, Thomas Shenk, "Adenoviridae and their Replication," and M. S. Horwitz, "Adenoviruses," Chapters 67 and 68, respectively, in VIROLOGY, B. N. Fields et al., eds., 3d ed., Raven Press, Ltd., New York (1996) and other references cited herein. [0012] Preferably, the viral vector particle is replication-deficient. By "replication- deficient" is meant that the viral vector particle comprises a genome that lacks at least one replication-essential gene function. A deficiency in a gene, gene function, or gene or genomic region, as used herein, is defined as a deletion of sufficient genetic material ofthe viral genome to impair or obliterate the function ofthe gene whose nucleic acid sequence was deleted in whole or in part. Replication-essential gene functions are those gene functions that are required for replication (i.e., propagation) of a replication-deficient viral vector. The essential gene functions ofthe viral vector particle will vary with the type of viral vector particle at issue. Examples of replication-deficient viral vector particles are described in, e.g., Marconi et al, Proc. Natl. Acad. Sci. USA, 93(21), 11319-20 (1996), Johnson and Friedmann, Methods Cell Biol, 43 (pt. A), 211-30 (1994), Timiryasova et al, J. Gene Med, 3(5), 468-77 (2001), Burton et al., Stem Cells, 19(5), 358-77 (2001), Kim et al., Virology, 282(1), 154-67 (2001), Jones et al., Virology, 278(1), 137-50 (2000), Gill et al., J. Med. Virol, 62(2), 127-39 (2000), Chen and Engleman, J. Virol, 74(17), 8188-93 (2000), Marconi et al., Gene Ther., 6(5), 904-12 (1999), Krisky et al, Gene Ther., 5(11), 1517-30 (1998), Bieniasz et al., Virology, 235(1), 65-72 (1997), Strayer et al., Biotechniques, 22(3), 447-50 (1997), Wyatt et al., Vaccine, 14(15), 1451-8 (1996), and Penciolelli et al., J Virol, 61(2), 579-83 (1987).

[0013] The replication-deficient (i.e., replication-defective) viral vector particle is preferably a replication-deficient adenoviral vector particle. Adenovirus replication- essential gene functions are encoded by, for example, the adenoviral early regions (e.g., the El, E2, and E4 regions), late regions (e.g., the L1-L5 regions), genes involved in viral packaging (e.g., the IVa2 gene), and virus-associated RNAs (e.g., VA-RNA I and/or VARNA II). Preferably, the replication-deficient adenoviral vector comprises an adenoviral genome deficient in two or more gene functions required for viral replication. The two or more regions ofthe adenoviral genome are preferably selected from the group consisting of the El, E2, and E4 regions and portions thereof (e.g., the E4-ORF6 region, El A region, and/or the E1B region). More preferably, the replication-deficient adenoviral vector comprises a deficiency in at least one replication-essential gene function of the El region (denoted an El -deficient adenoviral vector). In addition to such a deficiency in the El region, the replication-deficient adenovirus also can have a mutation in the major late promoter (MLP), as discussed in International Patent Application WO 00/00628. More preferably, the vector is deficient in at least one replication-essential gene function ofthe El region and at least part ofthe nonessential E3 region (e.g., an Xba I deletion ofthe E3 region) (denoted an E1/E3 -deficient adenoviral vector).

[0014] It is generally preferred that the adenoviral vector particle is "multiply deficient," meaning that the adenoviral vector particle is deficient in one or more gene functions required for viral replication in each of two or more regions ofthe adenoviral genome. For example, the aforementioned El-deficient or El/E3-deficient adenoviral vector particle can be further deficient in at least one replication-essential gene function ofthe E4 region (denoted an El/E4-deficient adenoviral vector). An adenoviral vector particle deleted ofthe entire E4 region can elicit a lower host immune response. Adenoviral vector particles comprising particular portions ofthe E3 region also exhibit lower host immune responses than adenoviral vectors lacking the entire E3 region. As such, it is desirable that the adenoviral vector comprises such portions ofthe E3 region. Such portions include, for example, both the 19 kDa and 14.7 kDa E3 proteins. The 14.7 kDa E3 protein is thought to inhibit tumor necrosis factor-mediated immune responses. The 19 kDa E3 protein is thought to be involved in evasion of infected cell recognition by cytotoxic T lymphocytes (CTL) (see, e.g., Sparer et al., J Virol, 70(4), 2431-2439, 1996). Deletion of other portions ofthe E3 region is desirable inasmuch as the region is non-essential to adenovirus replication and the deletion further reduces the likelihood of replication competent adenovirus (RCA) formation in complementing cell lines through homologous recombination.

[0015] Alternatively, the adenoviral vector particle lacks replication-essential gene functions in all or part ofthe El region (e.g., the El A region and/or E1B region, or portion of either region) and all or part ofthe E2 region (denoted an El/E2-deficient adenoviral vector). Adenoviral vectors lacking replication-essential gene functions in all or part ofthe El region, all or part ofthe E2 region, and all or part ofthe E3 region also are contemplated herein. If the adenoviral vector is deficient in a replication-essential gene function ofthe E2A region, the vector preferably does not comprise a complete deletion ofthe E2A region. More particularly, it is preferable that the multiply replication-deficient adenoviral vector contain the portion ofthe E2A region ofthe adenoviral genome. In particular, for example, the desired portion ofthe E2A region to be retained is that portion ofthe E2A region ofthe adenoviral genome which is defined by the 5' end ofthe E2A region, specifically positions Ad5(23816) to Ad5(24032) ofthe E2A region of an adenoviral genome of serotype Ad5. [0016] The adenoviral vector particle can be deficient in replication-essential gene functions of only the early regions ofthe adenoviral genome, only the late regions ofthe adenoviral genome, or both the early and late regions ofthe adenoviral genome. The adenoviral vector particle also can have essentially the entire adenoviral genome removed, in which case it is preferred that at least either the viral inverted terminal repeats (ITRs) and one or more promoters or the viral ITRs and a packaging signal are left intact (such viral vectors may be referred to as adenoviral amplicons). Such viral vectors can accommodate a nucleic acid insertion of at least about 35 kb (e.g., an adenoviral amplicon consisting essentially of only the ITRs, packaging signal, and foreign nucleic acid can accommodate an insertion of about 37-38 kb). By the inclusion of a spacer element in any or all ofthe deficient adenoviral regions, or retention of adenoviral genome sequences, the capacity of the adenoviral vector particle for large inserts can be reduced to any suitable amount. Suitable replication-deficient adenoviral vector particles, including multiply deficient adenoviral vector particles, are disclosed in U.S. Patents 5,851,806 and 5,994,106, International Patent Applications WO 95/34671 and WO 97/21826, and other references cited herein. An especially preferred adenoviral vector particle for use in the present inventive method is that described in International Patent Application PCT/US01/20536. [0017] The deletion of different regions ofthe adenoviral vector particle can alter the immune response ofthe mammal to the vector (examples of such deletions are briefly discussed elsewhere herein). In particular, the deletion of different regions can reduce the inflammatory response generated by the adenoviral vector particles (e.g., the E4 region as discussed above). Furthermore, the coat proteins ofthe adenoviral vector particles can be modified so as to decrease the ability or inability ofthe host cell neutralizing antibodies directed against the wild-type coat protein to bind with and/or inactivate the adenoviral vector particles. Examples of viral vector particles comprising such coat protein modifications are described in International Patent Application WO 98/40509. Examples of other suitable "stealth" viruses are described in, e.g., Martin, Exp. Mol. Pathol, 66(1), 3-7 (1999), Croyle et al., J Virol, 75(10), 4792-801 (2001), Rollins et al, Hum. Gene Ther., 7(5), 619-26 (1996), Ikeda et al., J. Virol, 74(10), 4765-75 (2000), and Halbert et al., J Virol, 74(3), 1524-32 (2000). Strategies for reducing immune response to the viral vector particle upon administration to a host are provided in Maione et al., Proc. Natl. Acad. Sci. USA, 98(11), 5986-91 (2001), Morral et al, Proc. Natl. Acad. Sci. USA, 96(22), 2816-21 (1999), U.S. Patents 6,093,699 and 6,211,160, and U.S. Patent Application 2001- 0066947A1. Preferred viral vector particles and strategies for reducing host immune responses are provided in Pastore et al., Hum. Gene Ther., 10(11), 1773-81 (1999), Morsy et al., Proc. Natl. Acad. Sci. USA, 95(14), 7866-71 (1998), Joos et al., Hum. Gene Ther., 7(13), 1555-66 (1996), Kass-Eisler et al., Gene Ther., 3(2), 154-62 (1996), U.S. Patent Application 2001-0066947A1, and U.S. Patent 6,225,113,.

[0018] The adenoviral vector particle genome preferably contains a packaging domain, such that the adenoviral genome produced from infection of suitable host cells with such particles can be packaged into an adenoviral vector particle. The packaging domain can be located at any position in the adenoviral genome, so long as the adenoviral genome is packaged into adenoviral particles. Preferably, the packaging domain is located downstream ofthe El region. More preferably, the packaging domain is located downstream ofthe E4 region. In a particularly preferred embodiment, the replication-deficient adenoviral vector lacks all or part ofthe El region and the E4 region. In this preferred embodiment, a spacer (i.e., a transcriptionally inert nucleic acid sequence) is inserted into the El region or into the E4 region, a desired heterologous nucleic acid sequence (e.g., a nucleic acid sequence encoding a TNF-α) is located in the E4 region or the El region, respectively, and the packaging domain is located downstream ofthe E4 region. Thus, by relocating the packaging domain, the amount of potential overlap between the adenoviral vector particle genome and the cellular/helper virus genome used to propagate the replication-deficient adenoviral vector particle is reduced.

[0019] The coat proteins ofthe adenoviral vector particle also can be manipulated to alter the binding specificity ofthe resulting adenoviral particle. Suitable modifications to the coat proteins include, but are not limited to, insertions, deletions, or replacements in the adenoviral fiber, penton, pIX, pllla, pVI, or hexon proteins, or any suitable combination thereof, including insertions of various native or non-native ligands into portions of such coat proteins. Examples of adenoviral vector particles with modified binding specificity are described in, e.g., Reynolds et al., Mol. Ther., 2(6), 562-78 (2000) and U.S. Patents 5,871,727, 5,885,808, and 5,922,315. Preferred modified adenoviral vector particles include those described in, for example, Wickham et al., J. Virol, 71(10), 7663-9 (1997), Cripe et al., Cancer Res., 61(7), 2953-60 (2001), van Deutekom et al., J. Gene Med., 1(6), 393-9 (1999), McDonald et al., J Gene Med, 1(2), 103-10 (1999), Staba et al., Cancer Gene Ther., 7(1), 13-9 (2000), Wickham, Gene Ther., 7(2), 110-4 (2000), Kibbe et al., Arch. Surg, 135(2), 191-7 (2000), Harari et al, Gene Ther., 6(5), 801-7 (2000), Bouri et al, Hum Gene Ther., 10(10), 1633-40 (1999), Wickham et al., Nαt. Biotechnol, 14(11), 1570-3 (1996), Wickham et al., Cancer Immunol. Immunother., 45(3-4), 149-51 (1997), and Wickham et al, Gene Ther., 2(10), 750-6 (1995), and U.S. Patents 5,559,099; 5,712,136; 5,731,190; 5,770,442; 5,801,030; 5,846,782; 5,962,311; 5,965,541; 6,057,155; 6,127,525; and 6,153,435; and International Patent Applications WO 96/07734, WO 96/26281, WO 97/20051, WO 98/07865, WO 98/07877, WO 98/40509, WO 98/54346, WO 00/15823, and WO 01/58940. Other targeted viral vector particles are described in, e.g., Bartlett et al., Nat. Biotechnol, 17(2), 181-6 (1999), Engelstadter et al, Gene Ther., 8(15), 1202-6 (2001), Boerger et al., Proc. Natl. Acad. Sci. USA, 96(17), 9867-72 (1999), Gunzburg et al., J. Mol. Med., 74(4), 171-82 (1996), Miller et al., FASEB J., 9(2), 190-9 (1999), International Patent Applications WO 00/11201, WO 00/77167, WO 01/28569, and European Patent Application 1 001 032.

[0020] A quantity of viral vector particles sufficient for infection can be obtained using known techniques. Examples of such techniques are described in, e.g., Benton et al., In Vitro, 14(2), 192-9 (1978), Schilz et al., J Gene Med., 3(5), 427-36 (2001), Pan et al., J. Gene Med, 1(6), 2133-40 (1999), Reiser, Gene Ther., 7(11), 910-3 (2000), Andreadis et al, Biotechnol. Prog, 15(1), 1-11 (1999), Rotani et al, Hum Gene Tlier., 5(1), 19-28 (1999), Danthinne et al., Gene Ther., 7(20), 1707-14 (2000), and Hirala et al., J. Virol, 74(10), 4612-20 (2000). More particularly, adeno-associated viral vectors can be constructed and/or purified using the methods set forth, for example, in U.S. Patent 4,797, 368 and Laughlin et al., Gene, 23, 65-73 (1983). Similar techniques are known in the art with respect to other viral vectors, particularly with respect to herpes viral vectors (see, e.g., Lachman et al., Curr. Opin. Mol. Ther., 1(5), 622-32 (1999).

[0021] Construction of adenoviral vector particles is well understood in the art. Adenoviral vectors can be constructed and/or purified using the methods set forth, for example, in U.S. Patent 5,965,358, Donthine et al, Gene Ther., 7(20), 1707-14 (2000), and International Patent Applications WO 98/56937, WO 99/15686, and WO 99/54441. The production of adenoviral transfer vectors (or adenoviral genome constructs) also is well known in the art, and involves using standard molecular biological techniques such as those described in, for example, Sambrook et al., MOLECULAR CLONING: A LABORATORY MANUAL (Cold Spring Harbor Press 1989) and the third edition thereof (2001), Ausubel et al., CURRENT PROTOCOLS IN MOLECULAR BIOLOGY (Wiley Interscience Publishers 1995), and Watson et al., RECOMBINANT DNA, (2d ed.), and in several ofthe other references mentioned herein. Typically, production of a suitable genome encoding a recombinant adenoviral vector particle is produced by in vitro homologous recombination of two or more portions ofthe recombinant genome or by direct ligation of such portions to form a genome coding for the expression ofthe adenoviral vector particle Any suitable homologous recombination technique can be used to generate the adenoviral vector-producing plasmid. Examples of such techniques are provided in, e.g., Chinnadurai et al., J. Virol, 32, 623-28 (1979), Berkner et al., Biotechniques, 6, 616-28 (1998), Chartier et al, J. Virol, 70, 4805-10 (1996), and International Patent Application WO 96/25506. Commercially available systems for producing vectors using such techniques include the AdEasy system (Stratagene, La Jolla, CA). A preferred homologous recombination technique is described in International Patent Application WO 99/15686. Alternatively, any suitable ligation technique can be used, such as the techniques described in, e.g., Stow, J. Virol, 37(1), 171- 80 (1981), Stow, Nucl. Acids Res., 10(17), 5105-19 (1982), and Berkner et al., Nucl. Acids Res., 11(17), 6003-20 (1983). [0022] Replication-deficient adenoviral vector particles are typically produced in complementing cell lines that provide gene functions not present in the replication-deficient adenoviral vectors, but required for viral propagation, at appropriate levels in order to generate high titers of viral vector composition. A preferred cell line complements for at least one and preferably all replication-essential gene functions not present in a replication- deficient adenovirus. The complementing cell line can complement for a deficiency in at least one replication-essential gene function encoded by the early regions, late regions, viral packaging regions, virus-associated RNA regions, or combinations thereof, including substantially all adenoviral gene functions (e.g., to enable propagation of adenoviral amplicons, which comprise minimal adenoviral sequences, such as only inverted terminal repeats (ITRs) and the packaging signal or only ITRs and an adenoviral promoter). Most preferably, the complementing cell line complements for a deficiency in at least one replication-essential gene function (e.g., two or more replication-essential gene functions) of the El region ofthe adenoviral genome, particularly a deficiency in a replication-essential gene function of each ofthe El A and EIB regions. In addition, the complementing cell line can complement for a deficiency in at least one replication-essential gene function ofthe E2 (particularly as concerns the adenoviral DNA polymerase and terminal protein) and/or E4 regions of an adenoviral genome. Desirably, a cell that complements for a deficiency in the E4 region comprises an E4-ORF6 gene sequence (or a suitable functional (typically also structural) homolog thereof) and produces an E4-ORF6 protein or a functional homolog thereof, which desirably also is a structural homolog of a wild-type E4-ORF6 protein. Such a cell desirably comprises at least E4-ORF6 and no other open reading frame (ORF) ofthe E4 region ofthe adenoviral genome. In addition, the complementing cell line can complement for a deficiency in at least one replication-essential gene function ofthe El region and/or the E2 region (particularly as concerns the adenoviral DNA polymerase and terminal protein) and/or the E4 region ofthe adenoviral genome.

[0023] The cell line preferably is further characterized in that it contains the complementing genes in a non-overlapping fashion with the adenoviral vector, which minimizes, and practically eliminates, the possibility ofthe vector genome recombining with the cellular DNA. Accordingly, the presence of replication-competent adenovirus (RCA) is minimized, if not entirely avoided, in the viral vector particle composition, which, therefore, is suitable for therapeutic administration to a host. The lack of RCA in the vector composition avoids the replication ofthe adenoviral vector in non-complementing cells. The construction of complementing cell lines involves standard molecular biology and cell culture techniques, such as those described by Sambrook et al., supra, and Ausubel et al., supra. Complementing cell lines for producing the adenoviral vector include, but are not limited to, 293 cells (described in, e.g., Graham et al., J. Gen. Virol, 36, 59-72 (1977)), PER.C6 cells (described in, e.g., International Patent Application WO 97/00326, and U.S. Patents 5,994,128 and 6,033,908), and 293-ORF6 cells (described in, e.g., International Patent Application WO 95/34671 and Brough et al., J. Virol, 71, 9206-9213 (1997)). Such cells are further described elsewhere herein.

[0024] The viral vector particle desirably includes one or more heterologous nucleic acid sequences. A "heterologous nucleic acid sequence" is a nucleic acid sequence that is not native to the viral vector particle. The viral vector particle can comprise any suitable number of heterologous nucleic acid sequences. The heterologous nucleic acid sequence can be a RNA, a peptide, or a polypeptide with a desired activity. Alternatively, the heterologous nucleic acid sequence can encode an antisense molecule or a nucleozyme (e.g., a ribozyme). The heterologous nucleic acid sequence preferably comprises at least one nucleic acid sequence encoding at least one protein. The nucleic acid sequence encoding the protein can be obtained from any source, e.g., isolated from nature, synthetically generated, isolated from a genetically engineered organism, and the like. [0025] Any type of nucleic acid sequence (e.g., DNA, RNA, and cDNA) that can be inserted into the viral vector particle can be used in connection with the invention. The heterologous nucleic acid sequence preferably encodes a biologic activity in a host cell and can encode a peptide such as a cancer therapeutic, an angiogenic factor, an anti-angiogenic factor, or a neurotrophic factor, or can comprise a nucleic acid sequence with activity in a cell (e.g., an RNA sequence, a Cp6-rich immunoadjuvant DNA sequence, an antisense RNA sequence, and/or a ribozyme). The heterologous nucleic acid sequence can encode, for example, a member ofthe tumor necrosis factor super family of peptides (e.g., tumor necrosis factor-α (TNF-α), described in U.S. Patent 4,879,226), a vascular endothelial growth factor (NEGF) (e.g., a non-heparin-binding NEGF, such asNEGF₁₂₁NEGF₁₄₅, VEGF_165; VEGF₁₈₉, or VEGF_206j variously described in U.S. Patents 5,332,671, 5,240,848, and 5,219,739), or homologs thereof as described in, e.g., U.S. Patent Application 09/832,355 and references cited therein, a pigment epithelium-derived factor (PEDF) or a derivative thereof, (described in, e.g., U.S. Patent 5,840,686 and International Patent Applications WO 93/24529 and WO 99/04806), an atonal-associated factor (e.g., MATH-1 or HATH-1, described, e.g., in Birmingham et al, Science, 284, 1837-1841 (1999), and Zheng and Gao, Nature Neuroscience, 3(2), 580-586 (2000)), or an inducible nitric oxide synthase (iΝOS) (described, e.g., in Yancopoulos et al., Cell, 93, 661-64 (1998) and references cited therein).

[0026] The nucleic acid is preferably a secreted protein. By "secreted protein" is meant any peptide, polypeptide, or portion thereof, which is released by a cell into the extracellular environment. Additionally, the nucleic acid can encode a protein that affects splicing or 3' processing (e.g., polyadenylation), or a protein that affects the level of expression of another gene within the cell (i.e., where gene expression is broadly considered to include all steps from initiation of transcription through production of a processed protein), such as by mediating an altered rate of mRNA accumulation or transport or an alteration in post- transcriptional regulation.

[0027] The expression ofthe nucleic acid sequence encoding the protein is controlled by a suitable expression control sequence operably linked to the nucleic acid sequence. An "expression control sequence" is any nucleic acid sequence that promotes, enhances, or controls expression (typically and preferably transcription) of another nucleic acid sequence. Suitable expression control sequences include constitutive promoters, inducible promoters, repressible promoters, and enhancers. The nucleic acid sequence encoding the protein can be regulated by its endogenous promoter or, preferably, by a non-native promoter sequence. Examples of suitable non-native promoters include the cytomegalovirus (CMN) promoters, such as the CMN immediate-early promoter (described in, for example, U.S. Patent 5,168,062), promoters derived from human immunodeficiency virus (HIV), such as the HIN long terminal repeat promoter, the phosphoglycerate kinase (PGK) promoter, Rous sarcoma virus (RSN) promoters, such as the RSN long terminal repeat, mouse mammary tumor virus (MMTN) promoters, HSN promoters, such as the Lap2 promoter or the herpes thymidine kinase promoter (Wagner et al., Proc. Natl. Acad. Sci., 78, 144-145 (1981)), promoters derived from SN40 or Epstein Barr virus, an adeno- associated viral promoter, such as the p5 promoter, the sheep metallothionien promoter, the human ubiquitin C promoter, and the like. Alternatively, expression ofthe nucleic acid sequence encoding the protein can be controlled by a chimeric promoter sequence. The promoter sequence is "chimeric" in that it comprises at least two nucleic acid sequence portions obtained from, derived from, or based upon at least two different sources (e.g., two different regions of an organism's genome, two different organisms, or an organism combined with a synthetic sequence).

[0028] The promoter can be an inducible promoter, i.e., a promoter that is up- and/or down- regulated in response to an appropriate signal. Suitable inducible promoters include, for example, an ecdysone-inducible promoter, a tetracycline-inducible promoter, a zinc- inducible promoter (e.g., a metallothionein promoter), a radiation-inducible promoter (e.g., an EGR promoter), an arabinose-inducible promoter, a steroid-inducible promoter (e.g., a glucocorticoid-inducible promoter), or a pH, stress, or heat-inducible promoter. An expression control sequence up-regulated by a chemotherapeutic agent is particularly useful in cancer applications. The nucleic acid sequence preferably is operably linked to a radiation-inducible promoter, especially when the nucleic acid sequence encodes a TΝF. The use of a radiation-inducible promoter provides control over transcription ofthe nucleic acid sequence, for example, by the administration of radiation to a cell or host comprising the adenoviral vector. Any suitable radiation-inducible promoter can be used in conjunction with the invention. The radiation-inducible promoter preferably is the early growth region- 1 (Egr-1) promoter, specifically the CArG domain ofthe Egr-1 promoter. The Egr-1 promoter is described in detail in U.S. Patent 5,206,152 and International Patent Application WO 94/06916. The promoter can be introduced into the genome ofthe adenoviral vector by methods known in the art, for example, by the introduction of a unique restriction site at a given region ofthe genome. Alternatively, the promoter can be inserted as part ofthe expression cassette comprising the nucleic acid sequence coding for the protein, such as a TNF.

[0029] Preferably, the nucleic acid sequence encoding the protein further comprises a transcription-terminating region such as a polyadenylation sequence located 3' ofthe region encoding the protein. Any suitable polyadenylation sequence can be used, including a synthetic optimized sequence, as well as the polyadenylation sequence of BGH (Bovine Growth Hormone), polyoma virus, TK (Thymidine Kinase), EBV (Epstein Barr Virus), and the papillomaviruses, including human papillomaviruses and BPV (Bovine Papilloma Virus). A preferred polyadenylation sequence is the SV40 (human Sarcoma Virus-40) polyadenylation sequence.

[0030] Adenoviral vector particles can comprise a heterologous nucleic acid sequence in any suitable region ofthe adenoviral genome. The adenoviral vector particle can contain more than one heterologous nucleic acid sequence. In one embodiment, the heterologous nucleic acid sequences are located in separate regions ofthe adenoviral genome; however, the heterologous nucleic acid sequences also or alternatively can be placed next to each other, either upstream or downstream from one another, in the same region ofthe adenoviral genome. The heterologous nucleic acid sequence or sequences are preferably in a region of the adenoviral genome corresponding to a region wherein the adenoviral genome is deficient for a gene function required for viral propagation. For example, when the adenoviral vector is an El -deficient adenovirus, the nucleic acid sequence encoding the protein is preferably located in the El region ofthe adenoviral genome. The insertion of a nucleic acid sequence into the adenoviral genome (e.g., the El region ofthe adenoviral genome) can be facilitated by known methods, for example, by the introduction of a unique restriction site at a given position ofthe adenoviral genome. The heterologous nucleic acid sequence can be inserted into, e.g., the El region, the E2 region, the E3 region, the E4 region, or any combination thereof.

[0031] The viral vector particles are produced by infecting a population of cultured viral vector packaging (producing) cells with a viral vector particle (or population thereof). The cells can be any suitable type of cells for producing a viral vector composition. The cell can be a primary cell, such as a primary human retinal cell or primary African green monkey cell, or, more typically, will be an immortalized cell in a continuous cell line. Suitable cells include, for example, cells of primary cell lines, such as human embryonic kidney (HEK), human embryonic lung (HEL), and human embryonic retinoblasts. More particular examples of such cells include HEK-293 cells (Graham et al., Cold Spring Harbor Svmp. Quant. Biol, 39, 637-650 (1975)) and cells derived therefrom (e.g., 293-ORF6 cells, which are discussed elsewhere herein), W162 cells (Weinberg et al., Proc. Nat. Acad. Sci., 80, 5383-5386 (1983)), gMDBP cells (Klessig et al., Mol. Cell Biol, 4, 1354-1362 (1984); Brough et al., Virology, 190, 624-634 (1992)), A549 cells (ATCC No. CCL-185), R90 fibroblast cells (ATCC No. CCL-186) (see, e.g., Hay et al., Human Gene Ther., 10, 579-590 (1999)), NCI-H460 cells (ATCC No. HTB-177) (see, e.g., Lee et al., Int. J. Cancer, 88, 454-463 (2000)), HCT116 cells (ATCC No. HCL-247) (see, e.g., Ries et al., Nature Medicine, 6, 1128-1133 (2000)), NCI-H1299 cells (ATCC CRL-5803), and Calu-1 cells (ATCC HTB-54).

[0032] Suitable cells also include human embryonic retinal (HER) cells such as 911 cells (Fallaux et al., Human Gene Therapy, 7, 215-222 (1996) and PER.C6 cells (Crucell - Lieden, Netherlands (formerly Introgene, Inc.), described in, e.g., International Patent Application WO 97/00326). Alternatively, the cell is preferably a HeLa cell (ATCC CCL- 2) or an ARPE- 19/HPN- 16 cell (ATCC CRL-2502). Suitable cells also include renal carcinoma cells, WI38 cells and other human fibroblast cells, CHO cells, KB cells, SW-13 cells, MCF7 cells, and African green monkey cells (e.g., Vero cells). [0033] Other suitable cells include, for example, lung carcinoma cells such as ΝCI-H2126 cells (ATCC No. CCL-256), NCI-H23 cells (ATCC No. CRL-5800), NCI-H322 cells (ATCC No. CRL-5806), NCI-H358 cells (ATCC No. CRL-5807), NCI-H810 cells (ATCC No. CRL-5816), NCI-HI 155 cells (ATCC No. CRL-5818), NCI-H647 cells (ATCC No. CRL-5834), NCI-H650 cells (ATCC No. CRL-5835), NCI-H1385 cells (ATCC No. CRL- 5867), NCI-H1770 cells (ATCC No. CRL-5893), NCI-H1915 cells (ATCC No. CRL-5904), NCI-H520 cells (HTB-182), andNCI-H596 cells (ATCC No. HTB-178). Also suitable are squamous/epidermoid carcinoma cells that include HLF-a cells (ATCC No. CCL-199), NCI-H292 cells (ATCC No. CRL-1848), NCI-H226 cells (ATCC No. CRL-5826), Hs 284.Pe cells (ATCC No. CRL-7228), SK-MES-1 cells (ATCC No. HTB-58), and SW-900 cells (ATCC No. HTB-59), large cell carcinoma cells (e.g., NCI-H661 cells (ATCC No. HTB-183)), and alveolar cell carcinoma cells (e.g., SW-1573 cells (ATCC No. CRL-2170)). Additional examples of suitable cells are described, for example, in U.S. Patent 5,994,106 and International Patent Application WO 95/34671. Cells that have been demonstrated as suitable for particular viral vector particles are described in, e.g., Inoue et al., J. Virol, 72(9), 7024-31 (1998), Polo et al., Proc. Natl. Acad. Sci, 96(8), 4598-603 (1999), Farson et al., J Gene Med, 1(3), 195-209 (1999), Sheridan et al., Mol. Ther., 2(3), 262-75 (2000), Chen et al., Gene Ther., 8(9), 697-703 (2001), and Pizzaro et al., Gene Ther., 8(10), 737- 745 (2001).

[0034] Particularly preferred cells include cells that are capable of complementing a replication-deficient viral vector particle (e.g., a cell capable of complementing the production of an AAV viral vector particle or a replication-deficient adenoviral vector particle by inclusion of one or more nucleic acids that provide gene functions necessary for the replication of such vector particles). Examples of suitable cells in this context include, e.g., 293/E4, 293-ORF6, and 293/E4/E2A cells, which are described in, e.g., U.S. Patents 5,851,806 and 5,994,106. Additional appropriate cell lines can be generated using standard molecular biology techniques, such as those set forth in, e.g., Sambrook et al., supra, Ausubel et al., supra, Mulligan, Science 260, 926-932 (1987 and 1993), and Watson et al., supra. Additional molecular biology techniques related to the production of recombinant cells, vectors, and other genetically modified compositions are described in, e.g., Friedman, Therapy For Genetic Diseases (Oxford University Press, 1991), Ibanez et al., EMBO J, 10, 2105-10 (1991), Ibanez et al., Cell, 69, 329-41 (1992), and U.S. Patents 4,440,859, 4,530,901, 4,582,800, 4,677,063, 4,678,751, 4,704,362, 4,710,463, 4,757,006, 4,766,075, and 4,810,648

[0035] The cells can be maintained in any suitable medium to form a culture. The culture of cells can be any culture suitable for the propagation of a viral vector particle. Examples of suitable types of cultures include perfusion cultures, substrate-supported cultures, microcarrier-supported cultures, fluidized bed cultures, and suspension cultures. Suspension cultures (independent of microcarriers) are particularly favored, including for example, shaker flask cultures, roller bottle cultures, and suspension bioreactor cultures. Such cultures and related culturing techniques are described in, e.g., ANIMAL CELL TECHNOLOGY, Rhiel et al., eds, (Kluwer Academic Publishers 1999), Chaubard et al., Genetic Eng. News, 20(18) (2000), Hu et al., ASM News, 59, 65-68 (1993), Hu et al., Biotechnol. Prog., 1, 209-215 (1985), Martin et al., Biotechnol, (1987), Freshney, CULTURE OF ANIMAL CELLS: A MANUAL OF BASIC TECHNIQUE, 4^TH ED., (Wiley, 2000), Mather, INTRODUCTION TO CELL AND TISSUE CULTURE: THEORY AND TECHNIQUE, (Plenum Press, 1998), Freshney, CULTURE OF IMMORTALIZED CELLS, 3^RD ED., (John Wiley & Sons, 1996), CELL CULTURE: ESSENTIAL TECHNIQUES, Doyle et al., eds. (John Wiley & Sons 1998), GENERAL TECHNIQUES OF CELL CULTURE, Harrison et al, eds, (Cambridge Univ. Press 1997), Wu et al., Curr. Opin. Biotechnol, 11(2), 205-208 (2000), and other references cited herein.

[0036] The medium can be any medium appropriate for maintaining the cells and propagating a viral vector particle or vectors therein. Mediums suitable for use in the invention, along with techniques used to develop new or modified mediums suitable for use in the context ofthe invention, are known in the art. In general, the medium will contain a selection of secreted cellular proteins, diffusible nutrients, amino acids, organic and inorganic salts, vitamins, trace metals, sugars, and lipids. The medium can also contain additional compounds such as growth promoting substances (e.g., cytokines). A suitable medium preferably has the physiological characteristics and conditions (e.g., pH, salt content, vitamin and amino acid profiles) under which the cells naturally flourish. Numerous commercial cell and medium combinations are available, and one of ordinary skill will readily be able to determine the desired conditions for the culture. [0037] The medium can be an undefined medium or a defined medium. An undefined medium is a medium where the specific contents ofthe medium (e.g., the type and amount of proteins and nutrients) are not known or specified by a set formula. Examples of suitable undefined mediums include mediums based on animal serum (e.g., fetal bovine serum (FBS) or fetal calf serum (FCS)) or which utilize an alternative nutritional source, for example, enzymatic digestions of meat, organs, or glands, as well as milk or hydrolysates of wheat gluten. Preferably, an undefined medium in the context ofthe present invention is a serum-free medium (SFM). Although SFM does not contain animal serum, SFM can still contain animal-derived components, e.g., albumin, fetuin, hormones, and "undefined" components such as organ extracts.

[0038] A defined medium is a medium with known contents or a medium that is prepared using a specific formula. A simple defined medium is, for example, a basal medium. A basal medium is generally composed of vitamins, amino acids, organic and inorganic salts, and buffers. Additional defined components, such as bovine serum albumin (BSA), can be added to make a basal medium more nutritionally complex and appropriate for the nutritional needs of a specific cell type. More complex suitable defined mediums include protein-free and protein-containing mediums. Preferably, a defined medium in the context ofthe present invention is an animal protein-free medium. An animal protein-free medium does not contain proteins of animal origin, but can contain proteins from other sources. [0039] A particularly preferred medium is an animal protein-free medium, which contains recombinant proteins and growth factors (particularly, e.g., epidermal growth factor (EGF) and insulin-like growth factor (IGF), the addition of which is described further herein), as well as lipids (e.g., cod liver extracts) and cholesterol in amounts suitable for culturing 293- derived cells (e.g., 293-ORF6 cells) to desired cell densities during the viral vector production process (prefened cell densities are discussed further elsewhere herein). Examples of commercially available prefened medias are ExCell 525 (JRH Biosciences), CD293 medium (GIBCO), SFMII medium (GIBCO), Gene Therapy Medium I for Retinoblastoma-like Cells (GTRB) medium (SIGMA), Pro293s medium (BioWhittaker), Gene Therapy Medium II (SIGMA), and PF293 (HyClone). It is also desirable that such media are supplemented with glutamine to obtain optimal growth. For example, cells grown in SFMII medium are preferably supplemented with glutamine to reach a glutamine concentration of about 4 mM.

[0040] Preferably, the medium contains glucose. Any suitable concentration of glucose appropriate for culturing cells to desired cell densities is appropriate. Preferably, when mammalian cells are utilized, the concentration of glucose in the medium is at least about 1- 5 gm/L, more preferably about 2-4 gm/L.

[0041] The culture can be prepared in any suitable manner that promotes the growth and sustenance ofthe cells. Typically the culture is initiated by inoculation of a suitable medium with a population of cells. The cells used to inoculate the medium can be cells that were previously frozen and stored. Preferably the cells were frozen under conditions suitable for maintaining a high percentage of viable cells in the culture for future use. Several methods of freezing cells for future use are known in the art, for example, by using liquid nitrogen. Examples of techniques for freezing and thawing such cells, without lysing the cells, are described in, e.g., U.S. Patent 6,168,941 and references cited therein. [0042] After the medium is inoculated with the cells, the cells are then "cultured" or cultivated under conditions to permit growth ofthe cells. Any suitable manner of culturing the cells that permits the growth ofthe viral vector-producing cells is suitable in the context ofthe present invention. The method of culturing such cells will depend upon the type of cell selected. Suitable culturing methods are well known in the art, and typically involve maintaining pH and temperature within ranges suitable for growth ofthe cells. Preferred temperatures for culturing are about 35-40° C, more preferably about 36-38° C, and optimally about 37° C. Preferably, the pH ofthe culture is maintained at about 6-8, more preferably at about 6.7-7.8, and optimally at about 6.9-7.5.

[0043] During the subsequent cultivation ofthe culture, the growth ofthe cells typically will follow a characteristic pattern composed of five stages. The first stage, or lag phase, occurs at the introduction of cells or storage culture into the medium to form the culture. Preferably, the cells or storage culture (i.e., the "inoculum") used to inoculate the medium will be composed of a high percentage of viable cells and a relatively fresh culture medium in order to reduce the length ofthe lag phase. The lag phase is typically followed by a log (or exponential) phase, in which cells divide at the maximum possible growth rate, thus increasing the number of total viable cells in the culture. The cell growth rate is dependent on the growth medium and growth conditions (e.g., aeration, pH level etc.), which are preferably optimized to promote cell growth during the log phase. The cell growth rate is limited by the maximum doubling time that is dependent upon cell type. The cell growth rate during the exponential phase is constant, but because each cell divides at a slightly different moment the growth curve rises gradually. The log phase is followed by a decelerating phase, where the rate of increase in viable cells in the culture decreases. The decelerating phase is followed by a stationary phase where the total number of viable cells in the culture does not increase further, an effect caused either by a lack of cell division or by a balanced ratio of cell division and cell death. If the cell culture is not harvested before or during the stationary phase, the culture moves through a second decelerating phase, wherein the total number of viable cells declines, followed by an exponential death phase. Cell density increases throughout the growth cycle ofthe culture. The concentration ofthe cells in the medium can be monitored while culturing the cells.

[0044] Cell growth rates, and thus the above-described growth cycle, can be determined by numerous techniques known in the art. Techniques focusing on total number of cells in the culture include: determining the weight ofthe culture, assessing culture turbidity, determining metabolic activity in the culture, electronic cell counting, microscopic cell counting of culture samples, plate counting using serial dilutions, membrane filter counting, and radioisotope assays. Mechanical systems for measuring cell density, based upon these and other principles and particularly suited for use in bioreactors, are reviewed in, for example, Junker et al., Bioprocess Engineering, 10, 195-207 (1994). More recently, mass spectrometry and other advanced analytical techniques have been used in a similar fashion (see, e.g., Behrendt et al., Cytotechnology, 14, 157-65 (1994), McCaffrey et al., In Vitro Cell. Dev. Biol, 24(3), 247-52 (1988), and Lyng et al, Magn. Reason. Med, 43(6), 828-36 (2000)). In the context ofthe present invention, any technique permissive for assessing cell density is suitable. Cell density of a culture can be determined spectrophotometrically or by using a counting chamber, such as a hemocytometer. Preferably, a hemocytometer is used. In brief, hemocytometer-based techniques involve taking a sample ofthe culture, counting (and possibly also examining) a statistically significant number of cells in a given space in the hemocytometer, and determining the density of cells in the culture using simple mathematical formulas.

[0045] During the culturing of particular types of cells, the perfusion of fresh medium through the culture is desirable. "Perfusion through" the culture means that a certain volume of medium is added to the culture and a substantially identical amount of medium is removed from the culture without removing a significant percentage ofthe cells in the culture. Perfusion can be carried out by any suitable technique. A bioreactor with perfusion capabilities is usually used to accomplish such perfusion in a microcarrier-free suspension culture. For continuous perfusion cultures, perfusion of fresh medium is taking place throughout culturing in contrast to "intense perfuction" which is discussed further herein. Typically, for continuous perfusion cultures, perfusion through the culture occurs at a rate of about 1-4 volumes of medium in the culture per day. Continuous perfusion is a suitable means for adding fresh medium to the culture to sustain the cells during culturing, but it is not effective in removing large amounts (e.g., over about 20%, 50%, 65%, or even higher percentages) of spent medium from the culture. Such techniques are particularly preferred with HER cells. Preferably, the suspension culture is maintained in a batch or fed-batch mode before and after perfusion ofthe fresh medium through the culture. Techniques for perfusing fresh medium through a culture are further described in U.S. Patent 6,168,941. [0046] Once the cell culture reaches an appropriate cell density or another appropriate indication is reached, the cells are contacted with viral vector particles under conditions permissive for infection ofthe cells. Any appropriate cell density within about 35-75%, for example, about 40% to about 70% (e.g., about 44-63%), more preferably about 55-70% (e.g., about 60-70%), even more preferably about 62-69% (e.g., about 65%) ofthe density of cells that would be (or will be) obtained in the medium when the growth ofthe culture is in the stationary phase is prefened, particularly for the production of adenoviral vector particles. Typically, such densities are achieved during the mid-to-late exponential phase of the culture. Preferred cell densities for a particular cell type suitable for production of an viral vector particle composition may vary somewhat within the range of 40-70% ofthe stationary phase density based on the particular cell type. Suitable densities allow for the production of high yields of assembled viral vector particles, particularly active/viable viral vector particles, in contrast to the mere production of proteins by the infected cells, which typically is associated with infecting cells at cell densities well above 70% ofthe stationary phase density.

[0047] The actual density of cells in the medium at stationary phase can be any suitable density. The specific stationary phase density for any culture will depend upon the specific components ofthe culture (e.g., type of cells and medium used), and will depend significantly on the type, and size, of culture. Typical stationary phase density can be about 1-9 x 10⁶ cells/ml. For example, for a 10 liter fed-batch or batch bioreactor of a HER cell culture, stationary phase density is typically about 1.5 x 10⁶-2.6 x 10⁶ cells/ml, more typically about 1.5 x 10⁶-2 x 10⁶ cells/ml. For cells cultured in 10-liter continuous perfusion bioreactors, the stationary phase density often is higher, such as about 5-6 x 10⁶ cells/ml for A549 cells in a 10-liter continuous perfusion bioreactor. In contrast, for 293 cells and cells of 293 -derived cell lines grown in a 10-liter continuous perfusion bioreactor, typically have a stationary stage cell density of about 7-9 x 10⁶ cells/ml. As fed batch, batch, and continuous perfusion cultures of at least 10 L in size typically are preferred, these cell densities represent preferred stationary phase cell densities in the practice ofthe invention. The number of cells in the medium when the culture is in the stationary phase can be determined by allowing some portion ofthe culture to progress to stationary phase or by assessing substantially similar cultures wherein the density ofthe culture at the stationary phase is determined. [0048] The density of cells in the medium during infection typically is about 0.8-4.2 x 10⁶ cells/ml. The density of cells in the medium during an intense perfusion is typically 0.8 x 10⁶-1.1 x 10⁶ cells/ml, more specifically about 1.0 x 10⁶-1.1 x 10⁶ cells/ml, in 10 liter fed batch and batch bioreactors. In a 10-liter fed-batch bioreactor, cell densities while the fresh medium is perfused through the culture can be about 0.8 x 10 -1.4 x 10 cells/ml, more specifically about 1.1 x 10⁶-1.3 x 10⁶ cells/ml. For a 10-liter continuous perfusion bioreactor such densities typically will be about 2.4 x 10⁶-4.2 x 10⁶ cells/ml. More particular cell densities for certain aspects ofthe invention are described elsewhere herein. [0049] The time to reach an appropriate cell density for infection will vary depending upon the vector, type of cells, and type of culture used during the cell growth cycle. For example, starting with frozen cells with a density of less than 3 x 10⁵ cells/ml, a period of about 6-10 days may be required to achieve the aforementioned cell densities. The culture can be grown in a single container or in multiple containers. For example, the culture can be grown initially in multiple roller bottles or spinner flasks until a desired cell density is achieved, then the separated culture can be unified in a single container, such as a bioreactor, in different bioreactors, or in multiple bioreactors at once. [0050] Besides direct measurement or monitoring ofthe cell density, one of ordinary skill in the art will be able to determine times or other indications that correspond to the aforementioned cell densities for the cells and culture used to produce the viral vector particle compositions. Thus, for example, a time corresponding to the cell density associated with optimal composition production can be determined for a particular composition and selected as an indicator of when the culture should be contacted with the viral vector particles in practicing the invention with a substantially similar composition (e.g., same cell type and same medium). Another technique that is available is the use of mathematical growth formulas, based on one or more sample points during the growth of the culture, such as the Monrod Model. Either type of technique, or other similar techniques, can be combined with mechanical monitoring techniques or other techniques for practicing the invention under such determined parameters.

[0051] In at least some aspects, the culture will desirably comprise at least about 50% spent medium (medium nutritionally used by the cells and/or containing the byproducts of cellular metabolism) at the time of contact with the viral vector particles. In such aspects, the cell culture desirably comprises at least about 60% spent medium, more preferably about 70% spent medium, even more preferably about 80% spent medium, advantageously about 90% spent medium, even more advantageously about 95% spent medium, and optimally about 100%) spent medium. Such techniques are particularly preferred with HEK cells and/or cells comprising a portion ofthe E4 region ofthe adenovirus genome (such as, e.g., 293- ORF6 cells). [0052] Alternatively, the culture can comprise a portion ofthe spent media, in an amount corresponding to any ofthe above-described percentages, which results in an increased yield in the production of viral vector particles from the cells with respect to a substantially identical culture containing less than the designated amount ofthe spent medium portion (or, preferably, substantially no spent medium). The increased yield in the production of viral vector particles from the cells is at least about a 30% increase, preferably at least about a 50% increase, more preferably at least about a 75% increase, more preferably at least about a 90% increase, more preferably at least about a 100% increase, still more preferably at least about an 150% increase, and most preferably about a 200% increase over a medium substantially free ofthe spent medium portion at lysis and/or after filtration and chromatography purification (desirably at both times). The portion ofthe spent medium will contain metabolites that induce the production of viral vector particles at an increased rate when present in one ofthe above-described amounts. The portion can be any suitable portion. The separation ofthe components ofthe spent medium to obtain the spent medium portion can be accomplished by any suitable technique, including, e.g., cell fractionation techniques (for example, differential centrifugation, velocity sedimentation, and density gradient centrifugation), chemical extraction techniques, biochemical techniques such as SDS-PAGE, or chromatography separation techniques.

[0053] Accordingly, in one sense the invention provides a method of producing an adenoviral vector particle composition comprising providing a culture comprising a population of human embryonic kidney (HEK) cells and at least about 50% spent culture medium (or a medium wherein at least about 50% ofthe medium comprises a portion of spent medium which increases viral vector production), infecting the cells with a population of adenoviral vector particles, and lysing the cells to obtain an adenoviral vector composition. Any suitable adenoviral vector particle can be produced in the method. The adenoviral vector particles are preferably replication-deficient adenoviral vector particles, which desirably are deficient in at least a portion ofthe E4 region ofthe adenoviral genome, and are more preferably also deficient in at least a portion ofthe El region ofthe adenoviral genome as well. The HEK cells are preferably E4-complementing cells that comprise at least a portion ofthe E4 region, e.g., the ORF6 region (e.g., 293-ORF6 cells, which are described in, e.g., International Patent Application WO 95/34671 and U.S. Patent 5,994,106).

[0054] The presence ofthe aforementioned concentration of spent medium preferably results in an increase in the number of adenoviral vector particles produced by performing a substantially identical production and purification process with a culture comprising a substantially identical population of cells and less than about 50% spent medium (typically with a culture comprising substantially no spent medium). Preferably, the cells are propagated in less than about 75% spent medium, less than about 80% spent medium, less than about 85% spent medium, more preferably less than about 90% spent medium, and most preferably less than about or about 100% spent medium. The substantially identical population of cells is preferably propagated in less than about 50% spent medium, more preferably less than about 40% spent medium, more preferably less than about 25% spent medium, and even more preferably less than about 10% spent medium (e.g., substantially no spent medium).

[0055] Spent medium cell culturing can be performed in any suitable type of cell culture using any suitable type of cell medium. Preferably, although the cells are infected in at least about 50% spent medium, fresh medium is added to the culture at about 4-30 hours after infecting the cell with the adenoviral vector particles, such that the amount of fresh medium in the culture is at least about 50%- 100% ofthe total medium in the culture immediately after such a medium addition. The fresh medium is preferably added at about 4-30 hours post infection (e.g., at about 5, 10, 15, 20, or 25 hours post infection or at any timepoint therein). The cells can be infected with adenoviral vector particles under any suitable conditions as described elsewhere herein at any suitable time after culturing and/or at any suitable cell density in the culture. Typically, the cells are infected when the culture has a cell density of at least about 1 x 10 cells/mL. Preferably, the cell density in the culture at infection is at least about 1 x 10⁵cells/mL, more preferably at least about 1 x 10⁶cells/mL, even more preferably at least about 1 x 10⁷cells/mL, still more preferably at least about 1 x 10⁸ cells/mL or higher (e.g., about 1 x 10⁹ cells/mL - 1 x 10¹¹ cells/mL). [0056] The invention also provides a method of producing a replication-deficient adenoviral vector composition comprising providing a culture comprising a population of adenovirus packaging cells containing a nucleic acid encoding a portion ofthe E4 region comprising E4-ORF6 (or a homolog thereof) and at least about 50% spent culture medium, infecting the cells with an E4-deficient adenoviral vector particle, and lysing the cells to obtain a replication-deficient adenoviral vector composition. The method can be further characterized with respect to time of infection, amount of spent medium in the culture, or another characteristic described above with respect to any other spent medium culture technique ofthe invention. The method produces more adenoviral vector particles than performing a substantially identical method in an identical cell line under identical conditions at any point viral vector particles are quantified.

[0057] In other aspects ofthe invention, the viral vector packaging cells are cultured under perfusion conditions (or at least in a bioreactor or other container capable of perfusion), which can be altered such that an "intense perfusion" is performed prior to contacting the cells with a viral vector particle. An "intense perfusion" occurs when fresh medium is perfused through the culture for about 1-6 hours in an amount of at least about 125%, preferably at least about 150%, and more preferably at least about 200% (e.g., about 2-3 times or about 3-4 times) the volume ofthe medium in the culture immediately prior to such perfusion. An intense perfusion provides fresh medium and removes substantial amounts of spent medium accumulated in the culture prior to the initiation ofthe intense perfusion. An intense perfusion can occur at any suitable rate and the ordinarily skilled artisan will readily be able to determine an appropriate rate for the particular system used. An intense perfusion results in about 66% or more ofthe spent media being removed from the culture (and replaced with fresh medium) prior to contact with the viral vector particles, for example, an intense perfusion of fresh medium in an amount equal to about three to four times the volume ofthe culture results in about 95% or more ofthe spent medium in the culture being removed (and thus replaced with fresh medium). Certain cells respond better to intense perfusion culturing than spent medium culturing with respect to the amount of viral vector particles produced. For example, intense perfusions techniques are preferably performed with, for example, HER cells and, particularly, El -complementing HEK cells. [0058] In most aspects, medium exchange during contact ofthe culture with the viral vector particles has surprisingly been found to be not necessary. In aspects where the cells are cultured by an intense perfusion technique, the perfusion ofthe fresh medium through the culture prior to infection is the only medium exchange used throughout the process of producing the viral vector particle composition. In situations where intense perfusion medium exchange is performed, it is typically preferred that other nutritional supplements are not added after infection (e.g., glucose) and that the cells are cultured in a batch mode. Medium exchange during or immediately after contacting the culture with the viral vector particle can result in the undesired removal of viable viral vector particles from the medium after their introduction to the culture.

[0059] In aspects where spent medium culture is performed in combination with a medium addition, the medium addition can be performed by any suitable technique. Preferably, the medium addition is performed by a perfusion method, such as an intense perfusion, or other perfusion method described herein. Desirably, in such aspects, the culture is maintained under batch conditions after such medium exchange is performed.

[0060] In situations where the cells are contacted with viral vector particles in at least about 50% spent medium, a medium exchange is desirably performed about 8-24 hours after infection, preferably about 10-22 hours after infection, more preferably about 12-18 hours after infection, most preferably about 14-16 hours post infection. The medium exchange can be performed using any suitable techniques appropriate for the system used and can be, for example, an "intense perfusion" as described herein, but preferably is performed by standard fed batch culturing techniques. [0061] Upon and after contact ofthe culture with the viral vector particles, the viral vector particles are permitted to infect the cells. Infection can be carried out under any suitable conditions. Conditions for viral vector particle infection can vary depending on the type of viral vector particle and cells utilized. For example, when using adenoviral vector particles and adenoviral packaging cell lines such as the HEK 293 cell line, the temperature ofthe culture during contact ofthe culture with the viral vector particles is about 35-40° C, more preferably about 36-38° C, and optimally about 37° C. The pH during contact ofthe culture with the adenoviral vector particles is preferably about 6.7-7.8, more preferably about 6.9- 7.5. Suitable infection conditions for other types of viral vector particles are described in, e.g., Bachrach et al., J. Virol, 74(18), 8480-6 (2000), Mackay et al., J. Virol, 19(2), 620-36 (1976), and Fields et al., supra. Additional techniques related to the production of viral vector particles, culturing of viral vector particle packaging cells, and infection of such cells with viral vector particles are described in, e.g., "Practical Molecular Virology: Viral Vectors for Gene Expression" in METHODS IN MOLECULAR BIOLOGY, vol. 8, Collins, M. Ed., (Humana Press 1991), VIRAL VECTORS: BASIC SCIENCE AND GENE THERAPY, 1st Ed. (Cid-Arregui et al., Eds.) (Eaton Publishing 2000), "Viral Expression Vectors," in CURRENT TOPICS IN MICROBIOLOGY AND IMMUNOLOGY, Oldstone et al., Eds. (Springer- Verlag, NY, 1992), "Viral Vectors" in CURRENT COMMUNICATIONS IN BIOTECHNOLOGY, Gluzman and Hughes, Eds. (Cold Spring Harbor Laboratory Press, 1988), INTRODUCTION TO MODERN VIROLOGY, 4th Ed., Dimmock and Primrose, Eds. (Blackwell Science 2001), BASIC VIROLOGY, 1st Ed., Wagner and Hewlett, Eds. (Blackwell Science 1999), PRINCIPLES OF VIROLOGY, Flint, Ed. (American Society for Microbiology, 1996), MOLECULAR METHODS FOR VIRUS DETECTION, Weidbrauk and Farkas, Eds. (Academic Press 1995), Cahn, PRINCIPLES OF MODERN VIROLOGY, 2nd Ed. (Academic Press, 1997), Burleson, VIROLOGY: A LABORATORY MANUAL (Academic Press), Gao et al., Adv. Virus Res., 55, 529-43 (2000), Grimm et al., Hum. Gene Ther., 10(15), 2445-50 (1999), Tom et al., Methods Mol. Biol, 39, 203-24 (1995), Anderson et al, J. Viol. Methods, 85(1-2), 23-34 (2000), Zolotukhin et al., Gene Ther., 6(6), 973-85 (1999), (no author), Prep. Biochem., 23(1-2), 1-284 (1993), and U.S. Patents 6,270,996, 6,261,551, 6,093,570, 5,858,740, 5,719,051, 5,681,731, and 5,506,129, and other references cited herein.

[0062] The present invention provides a method for preparing a cell culture comprising a population of adherent adenoviral vector packaging cells adapted to a serum-free suspension culture which efficiently express a nucleic acid that complements an adenovirus gene function comprising providing a monolayer of adenoviral vector packaging cells comprising a nucleic acid encoding a protein that complements at least one adenovirus gene function transcriptionally linked to an antibiotic resistance gene, washing the cell monolayer with a saline buffer, adding a serum-free medium to the cell monolayer in an amount sufficient to propagate the cells at a density below the lag phase, incubating the cells with the serum-free medium, adding an antibiotic or antibiotic analog to the cells such that cells not carrying the antibiotic resistance gene do not propagate, and suspending the cells in an serum-free medium with continuous shaking, rocking or rolling, such that a population of adenoviral vector packaging cells efficiently expressing a nucleic acid complementing an adenovirus gene function and that are adapted to an serum medium is obtained. The adenoviral vector packaging cells can be any suitable adenoviral vector packaging cells, for example, adenoviral vector packaging cells described herein. Preferably, the adenoviral vector packaging cells are complementing cells comprising at least a portion ofthe E4 region of the adenoviral genome. The E4 region ofthe adenoviral genome is desirably the ORF6 region. The cell culture is any suitable cell culture, as described above. The serum-free medium can be any suitable medium. An animal protein-free medium is particularly preferred.

[0063] The adenoviral vector packaging cells can comprise any nucleic acid encoding a protein that complements at least one adenovirus gene function, e.g., an E4 protein or an El protein. The nucleic acid encoding the complementing protein is transcriptionally linked to an antibiotic resistance gene. Antibiotic resistance genes are well-known in the art and include such genes as, e.g., hygromycin, puromycin, or neomycin resistance genes. The nucleic acid and antibiotic resistance gene can be transcriptionally linked in any suitable manner. The nucleic acid molecule is transcriptionally linked to an antibiotic resistance gene using methods known in the art (see, for example, International Patent Application WO 99/15686). Suitable antibiotic or antibiotic analogs for the method ofthe invention depend on the type of antibiotic resistance gene utilized, for example, linkage of a puromycin resistance gene to the nucleic acid encoding the complementing protein will necessitate the use of puromycin or a puromycin analog to effect selection ofthe cell. [0064] The cells are washed with a saline buffer. The saline buffer can be any suitable saline buffer. Thus, the saline buffer can be, for example, a phosphate buffered saline (PBS) buffer, a tris buffered saline (TRIS), a saline-sodium citrate buffer (SSC), a saline tris EDTA buffer (STE), a HEPES-buffered saline (HBS), or a MOPS-buffered saline (MBS). PBS saline buffers are especially preferred in the context ofthe invention. Any suitable amount of saline buffer can be used to wash the cells. Typically, the proper amount of saline buffer is dependant on the number of cells in the culture. For example, a cell culture of about 1 x 10⁵ to 1 x 10⁶ total cells could appropriately be washed with at least about 2 to 10 mL of PBS, more preferably with about 4 to 6 mL of PBS, most preferably with about 5 mL ofPBS.

[0065] Preferably, the cells are incubated with the serum-free medium for about 12-56 hours, more preferably about 24-48 hours, even more preferably about 36-48 hours. The cells can be incubated at any suitable temperature as described herein, any suitable carbon dioxide level described further herein, and can be agitated at any suitable rotations per minute (rpms) or can be incubated without agitation.

[0066] The cells are preferably suspended in a serum-free medium with continuous shaking, rocking or rolling, typically accomplished by mechanical means such as by a shaker, rocker, or roller.

[0067] The method further provides that the adenoviral vector packaging cells efficiently express a nucleic acid complementing an adenovirus gene function and that the cells are adapted to an serum medium. Cells can be tested for expression ofthe specific nucleic acid of interest by any suitable technique known in the art, e.g., by polymerase chain reaction, northern blotting, western blotting, or by the use of a marker gene to visualize levels of expression within the cell, for example, β-galactosidase. Cells can be tested for the infectivity ofthe adenoviral vector particles by any suitable technique in the art, for example, by performing a FFU assay, described supra.

[0068] The present invention further provides a method of producing a population of replication-defective adenoviral vector particles comprising providing a cell culture comprising a population of adenovirus packaging cells, which contain a nucleic acid sequence that encodes a protein which complements at least one adenovirus gene function, wherein the nucleic acid sequence is operably linked to a transcription control element that is upregulated in the presence of an inducer. The protein is toxic to the cells. The inducer is added to the culture at a time relative to the time of infecting the cells with a population of an adenoviral vector particles such that the inducer has minimum toxic effects on host cells, results in a maximized yield of adenoviral vector particles being produced by the cells, or preferably both. By minimum toxic effects is meant that cell viability remains at an acceptable level as described elsewhere herein. A maximized yield is obtained when the number of adenoviral vector particles produced in the presence of an inducer administered at a certain time is greater than the number of adenoviral vector particles produced in the absence ofthe inducer and/or in the presence ofthe inducer administered at a different time. A maximized yield can be any number of viral vector particles, for example, about 1 x 10 PU/cell-1 x 10¹⁵ PU/cell, or about 1 x 10² FFU/cell-1 x 10¹⁵ FFU/cell, or any other number or concentration of viral vector particles described herein. The maximized yield can be detected using any suitable technique for determining viral vector particle concentration, such as those described further herein. The inducer is added to the culture in an amount such that the transcription control element is detectably upregulated relative to the transcriptional control element in the absence of inducer. The detection of levels of gene expression can be performed using any suitable techniques. Examples of suitable techniques are discussed further herein. [0069] The cells comprising the nucleic acid are infected with a population of replication- deficient adenoviral vector particles, which comprise an adenoviral genome defective in at least one gene function complemented by the protein. After infection, the cells are cultured such that the cells produce a population of replication-deficient adenoviral vector particles. [0070] As in other contexts ofthe invention, the cells are desirably cultured in serum-free medium, which preferably is an animal protein-free medium.

[0071] The cells containing the inducer-linked nucleic acid sequence can be any suitable cells comprising a nucleic acid sequence that encodes a protein which complements at least one adenovirus gene function, e.g., an adenoviral E4 region or El region gene function. The cells can comprise more than one nucleic acid sequence that encodes a protein that complements at least one adenovirus gene function. Preferably, the cell comprises at least one protein that complements an E4 gene function, and more preferably which encodes E4- ORF6 or a protein that complements for the lack of E4-ORF6 in an E4-deleted vector/cell line system (e.g., and E4-ORF6 homolog), such that replication ofthe replication-deficient adenoviral vector particle is possible in the cell line comprising the nucleic acid. [0072] The nucleic acid sequence is operably linked to a transcription control element that is upregulated in the presence of an inducer. The transcriptional control element can be any suitable transcriptional control element that demonstrates increased activity in the presence of an inducer. Suitable transcriptional control elements include, for example, an ecdysone- inducible promoter, a tetracycline-inducible promoter, a zinc-inducible promoter (e.g., a metallothionein promoter), a radiation-inducible promoter (e.g., an EGR promoter), an arabinose-inducible promoter, a steroid-inducible promoter (e.g., a glucocorticoid-inducible promoter), or a pH, stress, or heat-inducible promoter.

[0073] The use of an inducible promoter to control a nucleic acid sequence that encodes a protein that complements at least one adenovirus gene function is especially beneficial when the complementing protein is toxic to the cells. Since the promoter requires the presence ofthe inducer for full activation, in the absence of inducer the toxic protein will not be expressed until the promoter is induced at the required time for optimal adenoviral vector particle production. Adenoviral proteins, especially, typically are toxic to a cell. For example, El proteins can be powerful transcriptional activators that induce viral replication by activating the cell replication cycle in host cells. El proteins can be oncogenic, resulting in transformation of normal cells to neoplastic cells. For example, the El A proteins have been linked to cellular transformation in vitro in cell cultures and in vivo in rodents (see, e.g., Bayley et al., Int. J. Oncol, 5, 425-444 (1994)). Furthermore, E1A proteins can be highly toxic to cells and, in some instances, instigate cell death through apoptosis, as well as enhancing cell killing by other agents, e.g., natural killer cells, macrophages, and cytokines such as human tumor necrosis factor (see, e.g., Querido et al. J. Virol, 71, 3526-3533 (1997); Routes et al., Virology, 277, 48-57 (2000); and Routes et al., J. Immunol, 165, 4522-4527 (2000)). The E4/ORF6 region has oncogenic potential as well (Moore et al. Proc. Nat. Acad. Sci. USA, 93, 11295-11301, 1996). As such, at least one ofthe El A and E4-ORF6 gene sequences in an adenovirus complementing cell are under the control of such an inducible promoter.

[0074] Preferably, the inducible promoter is a metallothionein promoter (e.g., a sheep metallothionein promoter). When the inducible promoter is a metallothionein promoter, the inducer is preferably zinc (alternatively copper can be used, but is less desired due to its toxic effects on cells). The zinc can be added to the cell culture at any time suitable for induction ofthe production ofthe complementary protein. Preferably, the zinc is added about 0-48 hours before the cell culture is infected with adenoviral vector particles. More preferably, the zinc is added at about 10- 36 hours before infection, still more preferably, the zinc is added at about 20- 28 hours before infection, and most preferably, the zinc is added at about 23- 25 hours before infection (e.g., at about 24 hours). [0075] In some aspects, it may be suitable to add the inducer (e.g., the zinc for a metallothionein-linked complementing sequence) after infection. In such instances, the inducer desirably is added about 0-36 hours after the cell culture is infected with viral vector particles. More preferably, the inducer is added at about 4- 24 hours after infection, and even more preferably, the inducer is added at about 8-12 hours after infection. [0076] In a metallothionein-promoter system, the concentration of zinc administered to the cells can be any suitable concentration appropriate for induction ofthe production ofthe complementary protein by the adenoviral vector particle packaging cells. Preferably, the zinc concentration is about 5 μM to about 100 μM, more preferably about 10 μM to about 80 μM, still more preferably about 20 μM to about 60 μM, even more preferably about 20 μM to about 40 μM (e.g., about 25 μM), and most preferably about 30 μM to about 40 μM (e.g., about 35 μM).

[0077] In this respect, the present invention further provides a method of producing a population of defective adenoviral vector particles comprising providing a culture comprising a population of adenovirus packaging cells comprising a nucleic acid sequence encoding at least part ofthe E4 region ofthe adenovirus genome including E4-ORF6, wherein the nucleic acid sequence is operably linked to a metallothionein promoter (a metallothionein promoter or any other promoter cited herein can be a naturally occurring promoter (which is preferred) or a homolog thereof (a promoter having at least about 75%, preferably at least about 85%, and optimally at least about 95% overall nucleic acid sequence identity to a wild-type counterpart promoter, here to a metallothionein promoter)), and adding zinc to the culture to obtain a zinc concentration of about 15 μM to about 50 μM (e.g., about 20-40 μM zinc, preferably about 25-35 μM zinc) at about 4 to about 36 hours before infecting the cells with an E4-deficient adenoviral vector particle, (preferably about 8-24 hours before infection, more preferably about 12-24 hours before infection). The cells are infected with a population of E4-deficient adenoviral vector particles, at an appropriate time (e.g., at a time where cells are at a preferred cell density as described elsewhere herein) and the cells are cultured such that a population of E4-deficient adenoviral vector particles is obtained.

[0078] The contact ofthe viral vector particles to the cells and incubation ofthe viral vector particle/cell composition to produce a population of viral vector infected cells through cell infection can be performed at any suitable cell density. In particular aspects, the concentration ofthe cells can be desirable prior to infection (such as by concentrating the medium to a density of about 3 x 10⁶ cells/mL, about 5 x 10⁶ cells/mL, or even higher). The cells can be concentrated in such aspects using any suitable technique, including, for example, density gradient centrifugation. In most aspects, however, the method is performed without the concentration ofthe cells prior to infection.

[0079] Any suitable number of viral vector particles can be used to infect the population of cells in any aspect ofthe invention. The number of viral vector particles used to infect the cells will depend on the number of cells in the culture, cell type, and viral vector particle type. For most viral vector particles and typical cell culture sizes under typical cell culture densities, the ratio of viral vector particles contacting with the culture to the cells in the culture (otherwise known as the multiplicity of infection (MOI)) desirably is greater than 1, and more preferably is at least about 5 (e.g., about 5-30, and preferably about 5-20). Such MOIs are suitable and preferred, for example, with respect to the use of adenoviral vector particles and adenoviral vector packaging cells (e.g., El -complementing HER cells, 293 cells, or 293-derived cells such as 293-ORF6 cells).

[0080] The culture can be, and, in most aspects preferably is, contacted with the viral vector particles without concentrating the cells prior to such contact. Thus, preferably the culture is not significantly concentrated before or during the contact ofthe culture with the viral vector particles and, most preferably, is not concentrated at all. The avoidance of concentrating the culture during the production ofthe viral vector particles is desirable inasmuch as the concentration process can involve the need for large and expensive equipment (e.g., a centrifuge capable of concentrating a 10 liter culture) and intensive labor. [0081] The contact ofthe viral vector particles under conditions permissive for infection can be performed for any suitable period of time that enables a desired level of infection of the cells with the viral vector particles. The time for infection will depend at least on the titer ofthe virus and the specific cell type employed (because some cell types may have a greater density ofthe receptor which the viral vector particle uses to attach to cells) and the available surface area available to the viral vector particles (which is a function ofthe culture type and/or the cell type employed). Additionally, the desired period of time can be affected by the type of viral vector particle utilized (e.g., the virus can have an altered coat protein through recombinant engineering or be conjugated with a chemical entity that affects its ability to bind to cells). One of ordinary skill in the art can determine an appropriate period of time for contact ofthe culture with the viral vector particles by taking such variables into account and using routine experimentation. For example, when using adenoviral vector particles based on serotype 5, a period of about one hour typically is sufficient under most conditions for infection, although longer periods (e.g., at least about 2, 3, 5, 10, 15, or 24 hours, or even longer) can be used. Typically, the period of contact ofthe cells with the viral vector particles, and the period of culture ofthe cells after such contact, are contemporaneous, as the culture is not concentrated and no medium exchange or other significant modification to the culture occurs after contacting the culture with the viral vector particles. Viral vector particles alternatively, though less preferably, can be initially obtained by transfection ofthe cells with a viral genome (e.g., a naked polynucleotide coding for production ofthe viral vector particle in the host cell). Examples of such techniques are described in, e.g., Sells et al. Proc. Natl. Acad. Sci. USA, 84(4), 1005-1009 (1987), U.S. patents 5,589,466 and 5,693,622 and references cited therein. [0082] The cell culture can be supplemented with any suitable growth factors in any suitable concentration. Desirably, the cell culture is supplemented with one or more growth factors in a concentration which increases the cell density in the culture. More preferably, the cell culture is supplemented with one or more growth factors in a concentration such that the yield of viral vector particles from the cells after infection and lysis (and/or after purification) is greater than the yield in the presence of a lower amount ofthe growth factors, such as the normal physiological amount ofthe growth factor or growth factors present in the cells. The growth factors that are added to the cell culture in this respect can be any suitable growth factors. Preferred growth factors include insulin-like growth factors (IGFs), epidermal growth factors (EGFs), members ofthe tumor necrosis factor-α family of proteins (additional aspects of which are discussed elsewhere herein), or protein homologs thereof. The IGF can be any suitable naturally occurring IGF, such as human IGF (as described in, e.g., U.S. Patents 5,158,875 and 5,340,725). The EGF can be any suitable EGF, including, for example, human EGF (as described in, e.g., U.S. Patents 4,528,186, 5,096,825, and 5,290,920).

[0083] A "homolog" in the context ofthe present invention (unless otherwise stated) can be any protein that (1) exhibits at least about 70% (desirably at least about 80%, preferably at least about 90%, and advantageously at least about 95%) total amino acid sequence identity to a naturally-occurring (i.e., wild-type) protein, (2) exhibits at least about 80% local sequence identity (desirably, at least about 90% local amino acid sequence identity, and advantageously at least about 95% local amino acid sequence identity) in a sequence of at least about 30 amino acid residues (preferably at least about 50 amino acid residues, more preferably at least about 100 amino acid residues, and more preferably at least about 150 amino acid residues) with an amino acid sequence contained in a naturally-occurring protein, and/or (3) exhibits at least about 80% overall amino acid sequence homology (based on amino acid function) (preferably at least about 90% amino acid sequence homology and more preferably at least about 95% amino acid sequence homology) to a wild-type protein. The homolog will desirably exhibit similar biological properties as its wild-type counterpart(s). For example, an E4-ORF6 homolog will desirably complement propagation of an E4-deleted adenoviral vector and an EGF homolog will desirably increase the yield of viral vector particles at a concentration similar to where a wild-type EGR would similarly increase viral vector particle yields.

[0084] "Identity" (sometimes referred to as "overall" identity) with respect to amino acid or polynucleotide sequences refers to the percentage of residues or bases that are identical in the two sequences when the sequences are optimally aligned. If, in the optimal alignment, a position in a first sequence is occupied by the same amino acid residue or nucleotide as the corresponding position in the second sequence, the sequences exhibit identity with respect to that position. The level of identity between two sequences (or "percent sequence identity") is measured as a ratio ofthe number of identical positions shared by the sequences with respect to the size ofthe sequences (i.e., percent sequence identity = (number of identical positions/total number of positions) x 100).

[0085] The "optimal alignment" is the alignment that provides the highest identity between the aligned sequences. In obtaining the optimal alignment, gaps can be introduced, and some amount of non-identical sequences and/or ambiguous sequences can be ignored. Preferably, if a gap needs to be inserted into a first sequence to achieve the optimal alignment, the percent identity is calculated using only the residues that are paired with a corresponding amino acid residue (i.e., the calculation does not consider residues in the second sequences that are in the "gap" ofthe first sequence). However, it is often preferable that the introduction of gaps and/or the ignoring of non-homologous/ambiguous sequences are associated with a "gap penalty."

[0086] A number of mathematical algorithms for rapidly obtaining the optimal alignment and calculating identity between two or more sequences are known and incoφorated into a number of available software programs. Examples of such programs include the MATCHBOX, MULTAIN, GCG, FASTA, and ROBUST programs for amino acid sequence analysis, and the SIM, GAP, NAP, LAP2, GAP2, and PIPMAKER programs for nucleotide sequences. Preferred software analysis programs for both amino acid and polynucleotide sequence analysis include the ALIGN, CLUSTAL W (e.g., version 1.6 and later versions thereof), and BLAST programs (e.g., BLAST 2.1, BL2SEQ, and later versions thereof). [0087] For amino acid sequence analysis, a weight matrix, such as the BLOSUM matrixes (e.g., the BLOSUM45, BLOSUM50, BLOSUM62, and BLOSUM80 matrixes), Gonnet matrixes (e.g., the Gonnet40, GonnetδO, Gonnetl20, Gonnetl60, Gonnet250, and Gonnet350 matrixes), or PAM matrixes (e.g., the PAM30, PAM70, PAM120, PAM160, PAM250, and PAM350 matrixes), are used in determining identity. BLOSUM matrixes are preferred. The BLOSUM50 and BLOSUM62 matrixes are typically most preferred. In the absence of availability of such weight matrixes (e.g., in nucleic acid sequence analysis and with some amino acid analysis programs), a scoring pattern for residue/nucleotide matches and mismatches can be used (e.g., a +5 for a match and -4 for a mismatch pattern). [0088] The ALIGN program produces an optimal global alignment ofthe two chosen protein or nucleic acid sequences using a modification ofthe dynamic programming algorithm described by Myers and Miller, CABIOS, 4, 11-17 (1988). Preferably, if available, the ALIGN program is used with weighted end-gaps. If gap opening and gap extension penalties are available, they are preferably set between about -5 to -15 and 0 to -3, respectively, more preferably about -12 and -0.5 to -2, respectively, for amino acid sequence alignments, and -10 to -20 and -3 to -5, respectively, more preferably about -16 and -4, respectively, for nucleic acid sequence alignments. The ALIGN program and principles underlying it are further described in, e.g., Pearson et al., Proc. Natl. Acad. Sci USA, 85, 2444-48 (1988), and Pearson et al., Methods Enzymol, 183, 63-98 (1990). [0089] The BLAST programs provide analysis of at least two amino acid or nucleotide sequences, either by aligning a selected sequence against multiple sequences in a database (e.g., GenSeq), or, with BL2SEQ, between two selected sequences. BLAST programs are preferably modified by low complexity filtering programs such as the DUST or SEG programs, which are preferably integrated into the BLAST program operations (see, e.g., Wooton et al., Compu. Chem., 17, 149-63 (1993), Altschul et al, Nat. Genet., 6, 119-29 (1994), Hancock et al., Comput. Appl. Biosci, 10, 67-70 (1994), and Wootton et al., Meth. in Enzym., 266, 554-71 (1996)). If a lambda ratio is used, preferred settings for the ratio are between 0.75 and 0.95, more preferably between 0.8 and 0.9. If gap existence costs (or gap scores) are used, the gap existence cost preferably is set between about -5 and -15, more preferably about -10, and the per residue gap cost preferably is set between about 0 to -5, more preferably between 0 and -3 (e.g., -0.5). Similar gap parameters can be used with other programs as appropriate. The BLAST programs and principles underlying them are further described in, e.g., Altschul et al, J. Mol. Biol, 215, 403-10 (1990), Karlin and Altschul, Proc. Natl. Acad. Sci. USA, 87, 2264-68 (1990) (as modified by Karlin and Altschul, Proc. Natl. Acad. Sci. USA, 90, 5873-77 (1993)), and Altschul et al., Nucl. Acids Res., 25, 3389-3402 (1997).

[0090] For multiple sequence analysis, the CULSTAL W program can be used. The CLUSTAL W program desirably is run using "dynamic" (versus "fast") settings. Preferably, nucleotide sequences are compared using the BESTFIT matrix, whereas amino acid sequences are evaluated using a variable set of BLOSUM matrixes depending on the level of identity between the sequences (e.g., as used by the CLUSTAL W version 1.6 program available through the San Diego Supercomputer Center (SDSC)). Preferably, the CLUSTAL W settings are set to the SDSC CLUSTAL W default settings (e.g., with respect to special hydrophilic gap penalties in amino acid sequence analysis). The CLUSTAL W program and underlying principles of operation are further described in, e.g., Higgins et al., CABIOS, 8(2), 189-91 (1992), Thompson et al, Nucleic Acids Res., 22, 4673-80 (1994), and Jeanmougin et al., Trends Biochem. Sci, 23, 403-07 (1998).

[0091] Several commercially available software suites incorporate the ALIGN, BLAST, and CLUSTAL W programs and similar functions, and may include significant improvements in settings and analysis. Examples of such programs include the GCG suite of programs and those available through DNASTAR, Inc. (Madison, Wisconsin). Particular preferred programs include the Lasergene and Protean programs sold by DNASTAR. [0092] Because various algorithms, matrixes, and programs are commonly used to analyze sequences, amino acid and polynucleotide sequences are preferably characterized in terms of approximate identities by indicating a range of identity "about" a particular identity (e.g., +/- 10%), more preferably +/- 8%, and even more preferably +/- 5% ofthe particular identity). Alternatively, an exact identity can be measured by using only one ofthe aforementioned programs, preferably one ofthe BLAST programs, as described herein. [0093] Local sequence identity can be determined using local sequence alignment software, e.g., the BLAST programs described above, the LFASTA program, or, more preferably, the LALIGN program. Preferably, the LALIGN program using a BLOSUM50 matrix analysis is used for amino acid sequence analysis, and a +5 match/-4 mismatch analysis is used for polynucleotide sequence analysis. Gap extension and opening penalties are preferably the same as those described above with respect to analysis with the ALIGN program. For LALIGN (or other program) analysis using k-tup value settings (also referred to as "k- tuple" or ktup values), a k-tup value of 0-3 for proteins, and 0-10 (e.g., about 6) for nucleotide sequences, is preferred.

[0094] An amino acid sequence of a homolog can also or alternatively exhibit significant (at least about 30%, preferably at least about 35%) sequence "homology" or "functional homology" to a wild-type growth factor, while failing to exhibit a significant level of amino acid sequence identity. Homology is a function ofthe number of corresponding conserved and identical amino acid residues in the optimal homology alignment. The "optimal homology alignment" is the alignment that provides the highest level of homology between two amino acid sequences, using the principles described above with respect to the "optimal alignment." Conservative amino acid residue substitutions involve exchanging a member within one class of amino acid residues for a residue that belongs to the same class. Protein portions (e.g., particular domains) containing conservative substitutions are expected to substantially retain the biological properties and functions associated with their wild-type counterpart or wild-type counterpart protein portions. The classes of amino acids and the members of those classes are presented in Table 1.

Table 1 - Amino Acid Residue Classes

[0095] A homolog preferably also or alternatively will exhibit high weight homology to a naturally occurring protein counterpart (e.g., an EGF homolog desirably will exhibit high weight homology to human EGF). "High weight homology" means that at least about 40%, preferably at least about 60%, and more preferably at least about 70% ofthe non-identical amino acid residues are members ofthe same weight-based "weak conservation group" or "strong conservation group" as the corresponding amino acid residue in the wild-type Growth factor. Strong group conservation is preferred. Weight-based conservation is determined on the basis of whether the non-identical corresponding amino acid is associated with a positive score on one ofthe weight-based matrices described herein (e.g., the BLOSUM50 matrix and preferably the PAM250 matrix). Weight-based strong conservation groups include Ser Thr Ala, Asn Glu Gin Lys, Asn His Gin Lys, Asn Asp Glu Gin, Gin His Arg Lys, Met He Leu Nal, Met lie Leu Phe, His Tyr, and Phe Tyr Trp. Weight-based weak conservation groups include Cys Ser Ala, Ala Thr Nal, Ser Ala Gly, Ser Thr Asn Lys, Ser Thr Pro Ala, Ser Gly Asn Asp, Ser Asn Asp Glu Gin Lys, Asn Asp Glu Gin His Lys, Asn Glu Gin His Arg Lys, Phe Nal Leu He Met, and His Phe Tyr. The CLUSTAL W sequence analysis program provides analysis of weight-based strong conservation and weak conservation groups in its output, and offers the preferred technique for determining weight-based conservation, preferably using the CLUSTAL W default settings used by SDSC.

[0096] Additionally, a homolog will desirably exhibit a similar hydropathy profile (hydrophilicity) to a wild-type protein (e.g., and IGF homolog can be a protein that exhibits a similar profile to human IGF). A hydropathy profile can be determined using the Kyte & Doolittle index, the scores for each naturally occurring amino acid in the index being as follows: I (+4.5), N (+4.2), L (+3.8), F (+2.8), C (+2.5), M (+1.9); A (+1.8), G (-0.4), T (- 0.7), S (-0.8), W (-0.9), Y (-1.3), P (-1.6), H (-3.2); E (-3.5), Q (-3.5), D (-3.5), Ν (-3.5), K (- 3.9), and R (-4.5) (see, e.g., U.S. Patent 4,554,101 and Kyte & Doolittle, J. Molec. Biol, 157, 105-32 (1982) for further discussion). Preferably, at least about 45%, preferably at least about 60%, and more preferably at least about 75% (e.g., at least about 85%, at least about 90%, or at least about 95%) ofthe amino acid residues which differ from the naturally occurring growth factor exhibit less than a +1-2 change in hydrophilicity, more preferably less than a +/-1 change in hydrophilicity, and even more preferably less than a +/-0.5 change in hydrophilicity. Overall, the homolog preferably exhibits a total change in hydrophilicity of less than about 150, more preferably less than about 100, and even more preferably less than about 50 (e.g., less than about 30, less than about 20, or less than about 10) from its wild-type counteφarts. Examples of typical amino acid substitutions that retain similar or identical hydrophilicity include arginine-lysine substitutions, glutamate-aspartate substitutions, serine-threonine substitutions, glutamine-asparagine substitutions, and valine- leucine-isoleucine substitutions. The GREASE program, available through the SDSC, provides a convenient way for quickly assessing the hydropathy profile of a growth factor. [0097] In yet another alternative, a homolog can comprise or consist of a peptide of at least about 40 amino acid residues, preferably at least about 75 amino acid residues, and more preferably at least about 150 (e.g., at least about 200, at least about 250, or more) amino acid residues encoded by a polynucleotide that hybridizes to (1) the complement of a polynucleotide that, when expressed, results in a naturally occurring protein counteφart, under at least moderate, preferably high, stringency conditions, or (2) a polynucleotide which would hybridize to the complement of such a sequence under such conditions but for the degeneracy ofthe genetic code. Alternatively, the homolog can comprise a sequence encoded by a polynucleotide that selectively hybridizes to a wild-type homolog-encoding polynucleotide of at least about 60 nucleotides (preferably at least about 120 nucletoides, and more preferably at least about 150 nucleotides, or more) with respect to other wild-type protein-encoding polynucleotide sequences (e.g., an IGF-encoding polynucleotide sequence with respect to an IGF homolog), and, more preferably selectively with respect to other wild-type proteins ofthe same organism, species, family, and/or kingdom. [0098] Exemplary moderate stringency conditions include overnight incubation at 37°C in a solution comprising 20% formamide, 0.5x SSC (150 mM NaCl, 15 mM trisodium citrate), 50 mM sodium phosphate (pH 7.6), 5x Denhardt's solution, 10% dextran sulfate, and 20 mg/mL denatured sheared salmon sperm DNA, followed by washing the filters in lx SSC at about 37-50°C, or substantially similar conditions, e.g., the moderately stringent conditions described in Sambrook et al., supra, and/or Ausubel, supra. High stringency conditions are conditions that use, for example, (1) low ionic strength and high temperature for washing, such as 0.015 M sodium chloride/0.0015 M sodium citrate/0.1% sodium dodecyl sulfate (SDS) at 50°C, (2) employ a denaturing agent during hybridization, such as formamide, for example, 50% (v/v) formamide with 0.1% bovine serum albumin (BSA)/0.1% Ficoll/0.1% polyvinylpyrrolidone (PVP)/50 mM sodium phosphate buffer at pH 6.5 with 750 mM sodium chloride, 75 mM sodium citrate at 42°C, or (3) employ 50% formamide, 5x SSC (0.75 M NaCl, 0.075 M sodium citrate), 50 mM sodium phosphate (pH 6.8), 0.1% sodium pyrophosphate, 5x Denhardt's solution, sonicated salmon sperm DNA (50μg/mL), 0.1 % SDS, and 10% dextran sulfate at 42°C, with washes at (i) 42°C in 0.2x SSC, (ii) at 55°C in 50% formamide and (iii) at 55°C in O.lx SSC (preferably in combination with EDTA). Additional details and explanation of stringency of hybridization reactions are provided in, e.g., Ausubel et al., CURRENT PROTOCOLS IN MOLECULAR BIOLOGY (Wiley h terscience Publishers 1995) and/or Sambrook et al., supra.

[0099] Another possibility is that the homolog comprises or consists of an amino acid sequence that is bound by an antibody that also binds a wild-type counteφart. For example, the growth factor can be a growth factor that is bound by wild-type EGF antibodies. Examples of wild-type EGF antibodies are described in, e.g., Dubiel et al, Patol. Pol, 43, 55-57 (1992) and Seiwerth et al., Folia Histochem Cytobiol, 34, 27-9 (1996). [00100] The production of new antibodies to the wild-type growth factors, and to the novel growth factors ofthe invention, also can be facilitated using any suitable technique known in the art. Examples of suitable techniques for obtaining such antibodies are provided in, e.g., Gavilodono et al., Biotechniques, 29(1), 128-32, 134-6, and 138 (passim) (2000), Nelson et al., Mol. Pathol, 53(3), 111-7 (2000), Laurino et al., Ann. Clin. Lab. Sci, 29(3), 158-66 (1999), Rapley, Mol. Biotechnol, 3(2), 139-54 (1995), Zaccolo et al., Int. J. Clin. Lab. Res., 23(4), 192-8 (1993), Morrison, Annu. Rev. Immunol, 10, 239-65 (1992), "Antibodies, Annigene, and Molecular Mimiery," Meth. Enzymol, 178 (John J. Langone, Ed. 1989), Moore, Clin. Chem., 35(9), 1849-53 (1989), Rosalki et al, Clin. Chim. Ada, 183(1), 45-58 (1989), and Tami et al., Am. J. Hosp. Pharm., 43(11), 2816-25 (1986), as well as U.S. Patents 4,022,878, 4,350,683, and 4,022,878. A preferred technique for producing antibodies is provided in Border et al., Proc. Natl. Acad. Sci, USA, 97(20), 10701-05 (2000). [00101] Suitable IGF and EGF homologs exhibit the ability to increase viral vector particle yield from viral vector particle infected cells upon lysis as compared to viral vector particle yields obtained from lysis of substantially identical viral vector particle infected cells at lower levels of IGF, EGF, or both, as applicable (e.g., physiologically normal levels of IGF, EGF, or both for the cell). Desirably, an IGF and/or EGF homolog will result in an increase in yield of at least about 75% and more preferably at least about 125% ofthe increase observed with culturing the cells in a similar amount ofthe homolog's wild-type counteφart.

[00102] The cell culture can comprise or be supplemented with any amount of IGF, EGF, or homologs thereof, capable of increasing the yield of adenoviral vector particle units per cell (and more desirably the number of fluorescent focus units produced per cell) as compared to a culture of such cells having a lower amount of IGF, EGF, or homolog thereof, such as a cell culture comprising normal physiological levels of IGF or EGF. The amount of IGF and/or EGF in the culture can be determined using any suitable technique. Example of techniques for assaying the level of IGF are described in, e.g., U.S. Patents 5,158,875 and 5,340,725. Examples of techniques for assaying the level of EGF in a composition are described in, e.g., U.S. Patents 4,528,186, 5,096,825, and 5,290,920. Culturing cells in medium containing an IGF and/or an EGF can be used for the production of any suitable viral vector particle (at levels lower than those where a cell-density independent yield of viral vector particles is obtained one or both ofthe growth factors can increase the growth rate and/or maximum density ofthe packaging cells. However, the use of IGF and/or EGF at levels which increase the yield of viral vector particles produced in cells cultured in the presence of such growth factors is particularly advantageous in the production of adenoviral vector particles.

[00103] In this respect, the present invention provides a method of producing an adenoviral vector particle composition comprising culturing a population of adenoviral packaging cells in a medium comprising at least about 1-50 ng/mL of an EGF (preferably about 5-50 ng/mL of an EGF, more preferably about 10-50 ng/mL of an EGF), about 1-50 ng/mL of an IGF (preferably about 5-50 ng/mL of an IGF, more preferably about 10-50 ng/mL of an IGF), or both, infecting the cells with an adenoviral vector particle, and culturing the cells to produce an adenoviral vector particle composition. The adenoviral vector particle ofthe present method can be any suitable adenoviral vector particle (e.g., a recombinant El-deficient, E3-deficient adenoviral vector particle), for example, any suitable adenoviral vector particle described herein. Preferably, the adenoviral vector particle in the context ofthe method is a multiply-deficient adenoviral vector, examples of which also are described elsewhere herein. [00104] The method can be practiced using any suitable type of adenoviral vector particle packaging cell, such as those described elsewhere herein. The packaging cell is desirably an HEK cell or an HER cell, and more preferably is a complementing HEK cell (e.g., a 293 cell, preferably a cell derived from 293-cells, and most preferably a 293-ORF6 cell). [00105] The cells can be cultured and infected in any suitable manner. Desirably, the culture is capable of supporting a population of adenoviral vector packaging cells at a cell density of about 1 x 10⁴ cells/mL to about 1 x 10¹⁰ cells/mL in a fed-batch mode, more preferably about 1 x 10⁶ cells/mL to about 1 x 10⁸ cells/mL, most preferably about 2 x 10⁶ cells/mL to about 4 x 10⁶ cells/mL. The cells are typically infected when the density of cells in the medium is about 40-70% ofthe density ofthe cells obtained in the medium when the growth ofthe culture is in the stationary phase, such as described elsewhere herein. Preferably, the cells are harvested between 36 and 60 hours post-infection, e.g., about 48 hours post infection. Desirably, at least about 1 x 10⁴ adenoviral vector particle units (e.g., at least about at least about 2.9 x 10⁴ adenoviral vector particle units), more preferably at least about lx 10 adenoviral vector particle units, even more preferably at least about 1 x 10⁸ adenoviral vector particle units, or most preferably at least about 1 x 10¹⁰ adenoviral vector particle units/cell are obtained at lysis and/or final purification ofthe adenoviral vector particle composition.

[00106] The medium can comprise any suitable amount of an EGF or EGF homolog, examples of which are described above. Typically and preferably, the medium will comprise about 5-50 ng/mL of an EGF, more preferably about 5-35 ng/mL of an EGF, even more preferably about 5-15 ng/mL of an EGF, and most preferably about 10 ng/mL of an EGF. The medium also or alternatively can comprise any suitable amount of an IGF or IGF homolog, examples of which are described above. Desirably, the medium further comprises about 5-50 ng/mL of an IGF, more preferably about 5-35 ng/mL of an IGF, even more preferably about 5-15 ng/mL of an IGF, and most preferably about 10 ng/mL of an IGF. Mediums which comprise both an IGF and an EGF in any ofthe aforementioned concentrations (preferably at about 10 ng/mL human wild-type IGF and 10 ng/mL human wild-type EGF) are particularly prefened.

[00107] The presence ofthe IGF, EGF, or both, in the medium can increase the adenoviral vector particle yield significantly. The presence ofthe EGF, IGF, or both, in the aforementioned concentrations preferably results in an at least about a 10% increase, desirably an at least about a 30% increase, more preferably an at least about a 50% increase, even more preferably an at least about a 60% increase, more preferably still an at least about an 80% increase, still more advantageously an at least about a 100% increase, and most preferably an at least about a 150% increase in particle unit/cell yield at lysis ofthe cells and/or final purification ofthe composition over culturing the cells (and, if applicable, purifying the composition) in a substantially identical medium lacking an increased level of EGF, IGF, or both over levels normally present in the cells.

[00108] The present invention also provides a method of producing adenoviral vector particles comprising culturing cells infected with adenoviral vectors in a culture medium containing r-insulin, dextran sulfate, and/or a pluronic (preferably, all three), which is free of α-Tocopheral Acetate, cod liver oil, or both, in the presence of at least about 1 ng/mL of an EGF, at least about 1 ng/mL of an IGF, or both. The medium can be any suitable medium, examples of which are described elsewhere herein. Desirably, the culture medium in such aspects is a defined medium, preferably a serum-free medium, and most preferably an animal protein-free medium. The cells are preferably cultured in the presence of about 1-50 ng/mL of an EGF, more preferably about 1-35 ng/mL of an EGF, even more preferably about 1-15 ng/mL of an EGF, and most preferably about 5 ng/mL of an EGF. Alternatively, or preferably additionally, the cells are cultured in the presence of about 1-50 ng/mL of an IGF, more preferably 1-35 ng/mL of an IGF, even more preferably about 1-15 ng/mL of an IGF, and most preferably about 5 ng/mL of an IGF. The IGF and EGF in these and other aspects ofthe invention can be replaced with a protein homolog that exhibits at least about 75%, preferably about 100%, and more preferably more than 100% ofthe biological activity of its wild-type counteφart (e.g., cell density-independent in adenoviral vector particle production) as discussed elsewhere herein.

[00109] The present invention further provides a cell culture comprising an adenoviral packaging cell, a medium containing r-insulin, dextran sulfate, a pluronic, and/or glutamine, in amounts sufficient to support the growth ofthe cell and production of adenoviral vector particles, and an amount of an EGF, an IGF, or both, sufficient to increase the per cell yield of adenoviral vector particles by at least about 20%, wherein the cell culture is desirably also free from α-Tocopheral Acetate, cod liver oil, or both. The medium can be any suitable medium and can contain other elements in addition to the listed elements. Preferably, the medium is a serum-free medium or an animal protein-free medium. Examples of commercially available mediums having the aforementioned qualities include SFMII medium, CD293 medium, GTRB medium, and combinations thereof, to which at least about 1-50 ng/mL of an EGF, about 1-50 ng/mL of an IGF, or both, has been added. The cells are preferably cultured in such cultures with the addition of about 1-50 ng/ml of an EGF, more preferably about 1-35 ng/mL of an EGF, even more preferably about 1-15 ng/mL of an EGF, and most preferably about 5 ng/mL of an EGF (e.g., human EGF), about 1-50 ng/mL of an IGF, more preferably 1-35 ng/mL of an IGF, even more preferably about 1-15 ng/mL of an IGF, and most preferably about 5 ng/mL of an IGF (e.g., human IGF), or, most preferably, a combination of both EGF and IGF at the aforementioned concentrations (other wild-type IGF, EGF, and/or IGF and EGF homologs also can be suitable at such concentrations in this aspect).

[00110] The present invention also provides a method of producing adenoviral vector particles comprising culturing cells capable of supporting the growth of adenoviral vectors in a culture for at least about 2 hours of exponential growth, administering about 5-50 ng/mL of an EGF, about 5-50 ng/mL of an IGF, or both to the culture, infecting the cells with a population of adenoviral vector particles, culturing the cells for a period sufficient to produce a desired yield of adenoviral vector particles, and lysing the cells to obtain a population of adenoviral vector particles from the culture. Preferably, about 5-50 ng/mL of an EGF and/or about 5-50 ng/mL of an IGF is administered to the medium. More preferably 5-35 ng/mL of an EGF, even more preferably about 5-15 ng/mL of an EGF, and most preferably about 10 ng/mL of an EGF in combination with about 5-50 ng/mL of an IGF, more preferably 5-35 ng/mL of an IGF, even more preferably about 5-15 ng/mL of an IGF, and most preferably about 10 ng/mL of an IGF is added to the medium. The cells can support at the growth of adenoviral vector particles in a culture for at least about 2 hours of exponential growth, more preferably about 4 hours of exponential growth, more preferably about 8 hours of exponential growth, even more preferably about 12 hours of exponential growth, still more preferably about 24 hours of exponential growth, and most preferably about 48 hours of exponential growth.

[00111] In aspects where the IGF, EGF, or both is added to a cell culture medium after the beginning of cell culturing and prior to lysis, the growth factor(s) can be added at any suitable point in the culturing ofthe viral vector packaging cells. Desirably, the cells are infected with the adenoviral vector before seven doublings ofthe culture (e.g., before 6 doublings, before 5 doublings, before 4 doublings, before 3 doublings or before 2 doublings).

[00112] After contacting the culture with the viral vector particles under conditions permissive for infection ofthe cells, the infected cells are cultured to complete production ofthe viral vector particle composition. Similarly to culturing the cells prior to contact, the infected culture can be cultured under any suitable conditions permissive for the propagation ofthe viral vector particles within the cells. Preferably, the pH ofthe culture is maintained at about 6.5-7.5, more preferably at about 6.9-7.3. Preferably, pH and/or other conditions will be maintained to optimize glucose metabolism by the cells while reducing the production of lactic acid in the culture. The pH of a cell culture can be controlled by any suitable method, preferably in a manner that does not substantially inhibit the production ofthe viral vector particle composition. Several suitable techniques for modifying pH are known in the art, including the addition of buffers (e.g., bicarbonate or tris buffers). Temperature is another factor that influences the production ofthe viral vector particle composition after infection. Any temperature suitable for the production ofthe viral vector particle composition can be utilized, preferably a temperature of about 35-40° C, more preferably about 36-38° C (e.g., about 37° C). Proper mixing ofthe culture is another condition which can be important to cell growth and viral vector particle production. Other factors which may be considered include oxygen concentration, CO₂ perfusion rate, concentration, settling and flow rates of cells in the culture, and levels of particular nutrients and/or intermediates that impact cell growth and metabolism rates (e.g., glutamine) (see, e.g., Ho et al., CRC Critical Reviews in Biotechnology, 4(2), 185-252 (1986); Kyung et al., Cytotechnology, 14, 183-90 (1994); Yoon et al., Biotechnology and Bioengineering, 44, 983-990 (1994); and Oeggerli et al., Biotechnology and Bioengineering, 45, 54-62 (1995)). The aforementioned principles and techniques, though discussed in the context of post-infection culturing ofthe culture, also are applicable to pre-infection culture ofthe culture described herein.

[00113] While the cells can be cultured by any method suitable for production of viral vector particles in infected cells under the aforementioned conditions, it is preferred that the infected cell culture is cultured in a bioreactor (also sometimes referred to as a fermentor) to produce large scale viral vector particle compositions. Any suitable bioreactor can be used, which ensures proper mixing and preferably optimal pH and temperature conditions for culturing the culture, and which enables the perfusion of fresh medium through the culture in an amount equal to at least about two times the volume ofthe culture prior to infection. Examples of suitable bioreactors include stirred tank bioreactors, bubble column bioreactors, air lift bioreactors, fluid bed bioreactors, packed bed bioreactors, wave bioreactors, and flocculated cell bioreactors. Preferably, the bioreactor is not a microprojectile-based or microcarrier-based bioreactor, a cell factory, or a cell cube bioreactor. Desirably, the bioreactor is a stirred tank bioreactor, which prevents cell damage by shearing and turbulence during culture. The bioreactor can be either a batch, continuous, or fed-batch bioreactor, with perfusion capabilities, and the culture preferably is maintained under batch, fed-batch, or continuous culture conditions with the exception of the perfusion of fresh culture through the medium prior to infection at a volume equal to at least about two times the volume ofthe medium prior to infection with the viral vector particles. Typically and preferably, perfusion culture-capable bioreactors are used with variable volume fed-batch procedures (also referred to in the art as repeated fed-batch process or cyclic fed-batch culture) or batch procedures during the culturing ofthe cells prior to, and after, the perfusion of fresh medium through the culture. After such perfusion and infection, batch conditions typically and preferably are maintained until harvest. Alternatively, continuous-perfusion cell culture conditions can be used in place of batch conditions during the initial growth ofthe cells and/or after infection, particularly in aspects where the cells are cultured by the "intense perfusion technique", where perfusion of fresh medium through the culture occurs in an amount significantly lower than the perfusion of at least two times the volume of medium in the culture performed prior to contact ofthe culture with the viral vector particles in such aspects.

[00114] A bioreactor can be any suitable size for producing an appropriate size viral vector particle composition. For large scale production, commercial 10 liter bioreactors, or larger bioreactors, are prefeπed. In aspects ofthe invention where roller bottles or other culture techniques are used prior to or during infection, cells can be transfeπed to the bioreactor by any appropriate techniques, such as a peristaltic pump transmission through a closed (i.e., environmentally isolated) transfer route, such as through SCD connection tubing or a sterilized steam block, as is described further herein. [00115] The present invention also provides a method of producing a population of complementary adenoviral packaging cells infected with replication-deficient adenoviral vectors. A population of at least about 1 x 10⁶ total adenoviral vector packaging cells in a medium are provided and expanded to at least about 1 x 10⁸ total cells. The cells are further expanded in at least one bioreactor to at least about 1 x 10⁹ total cells. The cells are then infected with viral vectors. The adenoviral vector packaging cells can be any suitable adenoviral vector packaging cells, for example, adenoviral vector packaging cells described herein. Preferably, the adenoviral vector packaging cells are complementing cells comprising at least a portion ofthe E4 region ofthe adenoviral genome. The E4 region of the adenoviral genome is preferably the ORF6 region. The cell culture is any suitable cell culture, as described above. The serum-free medium can be any suitable medium. An animal protein-free medium is particularly prefeπed.

[00116] Preferably, at least about 1 x 10⁶, more preferably at least about 1 x 10⁷, even more preferably at least about 1 x 10⁸ adenoviral vector packaging cells are provided. The cells are preferably expanded to at least about 1 x 10⁸, more preferably at least about 1 x 10⁹, even more preferably at least about 1 x 10¹⁰, still more preferably at least about 1 x 10¹¹ or more adenoviral vector packaging cells.

[00117] The cells are expanded in at least one bioreactor, as further described herein. The cells are preferably expanded in at least two bioreactors (i.e., expanded in a first bioreactor and then subsequently transfeπed to a second bioreactor for further expansion). The cells are preferably expanded in the bioreactors to at least about 1 x 10⁹, more preferably at least about 1 x 10¹⁰, even more preferably at least about 1 x 10¹², still more preferably at least about 1 x 10¹³, advantageously at least about 1 x 10¹⁴, or even more preferably at least about 1 x 10¹⁵ or more adenoviral vector packaging cells.

[00118] After culturing the infected cells, the cells are typically harvested from the culture, and the viral vector particle composition is produced by release ofthe viral vector particles from the cell. Any method of harvesting cells which will result in the recovery of viral vector particles can be used in the context ofthe present invention. Suitable methods of harvesting include methods of removing the cells from culture conditions such that the cells are no longer in conditions conducive to cell growth. When a bioreactor is utilized, harvesting can be accomplished by removal ofthe cells from the bioreactor (e.g., by a closed system comprising a peristaltic pump). The cells can be centrifuged down into a lower volume, or the cells can be maintained in the full amount of medium used during the infection process.

[00119] The cells preferably are harvested in the full amount of medium used during the infection process. Cells harvested in the full amount of medium can be maintained (stored) for any suitable period of time in a suitable container, e.g., in sterile plastic bags (which are prefeπed due to their ability to form a closed system with the container holding the harvested cells and the next device or container to be used in purifying the viral vector composition, their ability to freeze and thaw effectively due to their large surface area, their disposability, and low cost). Alternatively, the cells can be directly subjected to lysis and further purification methods.

[00120] Harvesting the cells can be done at any suitable time for deriving the desired composition of viral vector particles. Preferably, a harvesting time is selected that ensures optimal production of viral vector particles in the composition, balanced against efficiency of production by the cells in the culture. Such determinations will vary with cell type, but readily can be made. Typically, harvest will occur at about 24-60 hours, or longer, post- infection (hpi). Preferably, harvest will occur between about 24 hpi and 48 hpi, more preferably at about 36-48 hpi, advantageously at about 40-48 hpi, and most preferably at about 46-48 hpi.

[00121] The quality of viral vector particle composition production is dependent upon the viability ofthe cells at the time of infection. Accordingly, the culture desirably is contacted with the viral vector particles when the percentage of viable cells in the culture is such that a loss in the percentage of viable cells of 10% would result in an about 80% or more loss in focus forming units per cell (FFU/cell) when the cells are harvested. Similarly, the culture desirably is contacted with the viral vector particles when the percentage of viable cells in the culture is such that a loss in the percentage of viable cells of 20% would result in an about 90% or more loss in FFU/cell when the cells are harvested.

[00122] FFU represents the number of focuses formed by infected cells and is determined by means of an optical microscope using standard protocols. FFU/cell can be measured using any suitable technique for determining FFU/cell. Suitable techniques are described, for example, in Mentel et al, J. Virol. Methods, 59(1-2), 99-104 (1996), Weaver et al, Methods, 21(3), 297-312 (2000), Hitt et al, Mol. Biotechnol, 14(3), 197-203 (2000), Hierholzer et al, rcA. Virol, 80(1), 1-10 (1984).

[00123] Preferably, FFU/cell is measured using the following technique. Host cells are plated and allowed to attach overnight. The cell monolayers are then infected with a virus sample. After 1 hour of absoφtion into the cells, the viral sample is removed and the cells are covered in culture medium and incubated for about 24 hours at about 37 DC in a humidified CO incubator. During this time, the virus-infected cells begin to express the viral proteins. Cell monolayers are washed the next day and then fixed and permeabilized in methanol. Fixation and permeabilization allows the flu fluorescent reagents to penetrate the cells and bind to target antigens. Permeabilized cells are stained with fluorescein- conjugated monoclonal antibody against an early adenovirus nuclear protein (DNA-binding protein) for about 1 hour. After 1 hour incubation, the staining conjugate is washed off and the cells are visualized with an inverted fluorescence microscope. With the appropriate illumination, the fluorescein dye emits a green wavelength of light, which can be seen with the human eye under the microscope. Cells that have been infected with adenovirus have a fluorescent green nucleus because ofthe presence of DNA binding protein bound by the antibody conjugate. Only virus-infected cells stain with the conjugate. [00124] Cell viability can be determined by a number of techniques known in the art. A preferred technique is the dye exclusion technique, which utilizes an indicator dye to identify cell membrane damage. Cells that absorb the dye become stained and are considered non-viable. Dyes such as trypan blue, erythrosin, and nigrosin are commonly used. Preferably, trypan blue based assays are used. Further details of performing such methods and other cell culturing and analysis methods are provided in, for example, Lubiniecki, LARGE-SCALE MAMMALIAN CELL CULTURE TECHNOLOGY (Marcel Dekker, Inc., New York, 1990), Kostaninov et al, Trends in Biotechnol, 12, 324-33 (1994), Mather, "Making Informed Choices: Medium, Serum, and Serum-Free Medium", Chapter 2 in Methods in Cell Biology, 57, 19-30 (1998), Freshney, CULTURE OF ANIMAL CELLS (AlanR. Liss, Inc., 1987), Harrison, GENERAL TECHNIQUES OF CELL CULTURE (Cambridge Univ. Press 1997), ANIMAL CELL CULTURE METHODS, Barnes and Mather (eds.) (1998), Bonarius et al, Biotechnology and Bioengineering, 45, 524-35 (1995), and other references cited herein.

[00125] Preferably, the percentage of viable cells in the culture prior to infection (particularly, during and immediately after the intense perfusion) is maintained at about 75% or more ofthe total cells in the culture. More preferably, the percentage of viable cells in the culture prior to infection is about 80% or higher, more preferably about 85% or higher. Typically, in large cultures, the maximum sustainable percentages of viable cells in the culture will be about 95% (optimally, the percentage of viable cells is about 100%). The viability of cells can be monitored and/or determined by any appropriate technique, including those discussed elsewhere herein.

[00126] Alternatively, or in addition, the culture can be contacted with the viral vector particles when the percentage of viable cells in the culture is such that a loss in the percentage of viable cells of 10% would result in an about 80% or more increase in the ratio of viral particle units (PU) (total viral vector particle particles) per cell to focus forming units (FFU) or plaque forming units (PFU) per cell at harvest (in general, PFU measurements can be used in place of FFU measurements for any aspect herein, although FFU measurements are preferred and considered superior in most respects to PFU measurements). The total amount of PU can be determined by total viral titer techniques or other techniques suitable for determining the total number of viral vector particle particles. PFU can be determined by standard plaque assays, for example, by dyeing infected cells fixed with formalin with methylene blue solution (additional related techniques are discussed further herein). Other immunohistochemical and histochemical staining solutions and fixing techniques also can be used. The ratio of PU/FFU is an important indicator of the efficiency ofthe production of active viral vector particles. Lower ratios of PU/FFU indicate high ratios of active vectors to total vector production, indicating that the energy placed into vector production efficiently results in compositions of active vectors. Desirably, the PU/FFU ratio in the lysate and the viral vector particle compositions produced by the methods described herein is desirably about 100 or less, more desirably about 80 or less, even more desirably about 60 or less, advantageously about 40 or less, more advantageously about 30 or less, preferably about 25 or less, more preferably about 20 or less, even more preferably about 15 or less, favorably about 10 or less, and optimally about 5 or less. Techniques and combinations of techniques that produce such viral vector particle compositions are prefeπed.

[00127] The determination of when a loss in the active viral vector particles after lysis will occur due to such drops in the percentage of cell viability at the time of infection can be determined by studying a sample culture or previous culture performed under substantially similar conditions to determine the point where the culture should be contacted with the viral vector particles. The percentage of active viral vector particle can be determined by any appropriate techniques. Examples of such techniques include standard plaque assays and focus forming assays (which are preferred). A plaque forming unit (PFU) is a virus or group of viruses which cause a plaque (an area in a monolayer which displays a cytopathic effect, including shape and/or color changes indicative of cytopathicity (e.g., formation of dark round circles, or of visual white spots, depending on the cell and effect) and lack of cells due to virus-induced lysis), hi a standard plaque assay, monolayers of cells are cultured, infected with viral vector particles (or infected cells can be used in the beginning ofthe assay), overlaid with suitable overlay medium (e.g., agarose), and stained with an appropriate dye to visualize the cells (e.g., MTT solution (available through Sigma)). Plaques can then be counted by visual analysis. The number of plaques per mL or per cell can be determined by performing the necessary calculations to coπelate the assayed sample in the monolayer with the total culture. Total viral titer can be measured by any method known to those of skill in the art, examples of which are described in U.S. Patents 4,861,719 and 4,868,116.

[00128] In terms ofthe present invention, active viral vectors refer to viable viral vectors. The term "activity" is used herein with reference to viability (e.g., actual and/or potential viability) ofthe virus. The term "activity," as used in describing embodiments ofthe present invention in which the virus is retained in (or at least can be reconstituted to) an active state, refers to any suitable measure ofthe viability of a composition of a virus. Numerous measurements of virus activity are known in the art and can be used within the context ofthe present invention. At any particular time of testing, some time can be required to test the virus' activity (e.g., sufficient time for the viral vector to exhibit the characteristic to be measured). For example, if the test time is day zero (e.g., a cell is infected with a virus and subsequently stored in the composition on the same day), some time may be required on that day in order to observe the measured trait. [00129] An example of a suitable measure of virus activity (and thus the activity of the composition) is the infectivity ofthe virus. Infectivity can be determined by any number of suitable assays known in the art. Infectivity can involve determining the number of infected cells of a cell population contacted with a certain concentration of virus at a particular time (e.g., by counting the number of cells exhibiting moφhological changes indicative of infection with the virus). Infectivity also can be determined by a standard plaque assay (or, more preferably, and FFU assay) performed at different times using similar amounts ofthe virus (or composition comprising the virus) and similar cell medium. [00130] It is often desirable to use techniques different from, or building upon, the cell count or standard plaque assay, such as modified plaque assays, or combining the assay with the use of a computer program to facilitate determination of activity. Other suitable, and often preferred, assays for determining activity include performing immunological assays ofthe production of antiviral antibodies by a cell (e.g., by using an enzyme immunoassay (EIA), such as an ELISA, or a Western Blot assay) and/or measuring the production of cytokines (e.g., interferons) generated in response to the introduction ofthe virus into a given host. When infectivity ofthe virus is used as an assessment of activity, a suitable amount of time needs to be allowed for viral infection of a population of cells to occur prior to the determination of infectivity. [00131] Alternatively, viral activity can be determined by examining the ability ofthe viral vector particles to produce viral gene products within a host cell (e.g., a specific viral protein, polypeptide, glycoprotein, or RNA). When the virus is a viral gene transfer vector, activity desirably is a measure ofthe amount of gene product produced by cells (e.g., 293 cells, HER cells, A549 cells, or 293-ORF6 cells) infected by a sample comprising the viral gene transfer vector particles. The measurement of such a viral vector protein or other product (as with other measurements of activity) can be carried out by any suitable technique. For example, the micrograms of viral product produced per microliter of liquid composition can be determined under similar conditions at different test times. [00132] When the viral vector particle is a viral gene transfer vector, assays directed to the expression or presence ofthe transgene expressed by the viral vector particles also can be used to determine the percentage of active viral vector particles in the composition. Transgene expression can be measured using any technique suitable for quantifying the number of active viral vectors in the composition. For example, transgene expression can be determined by Northern Blot analysis (discussed in, e.g., McMaster et al, Proc. Natl. Acad. Sci. USA, 74, 4835-38 (1977) and Sambrook, supra), RT-PCR (as described in, e.g., U.S. Patent 5,601,820 and Zaheer et al., Neurochem. Res., 20, 1457-63 (1995), and in situ hybridization techniques (as described in, e.g., U.S. Patents 5,750,340 and 5,506,098). [00133] The precise measurement technique for viral activity will depend, to some extent, upon the particular composition, especially the particular virus preserved therein (e.g., the nature ofthe viral gene transfer vector and product(s) produced thereby). Techniques to perform the above-discussed assays are widely known in the art. Such techniques are discussed further, for example, in Fields et al. and Sambrook et al, supra. [00134] The viral vector particle-infected cells can be lysed using any suitable method to obtain a lysate (or crude viral vector particle composition). Suitable methods to produce a cell lysate include, but are not limited to, sonication, hypotonic solution lysis, hypertonic solution lysis, liquid shear (e.g., microfluidization), solid shear (e.g., French pressure cell lysis, Mickle shaker lysis, and Hughes pressure cell lysis), detergent lysis, or a combination thereof. The use of such techniques to disrupt cells, generally, is known in the art. Additional techniques and description are known in the art and can be found in U.S. Patent 6,168,941. Liquid shear, and, more particularly, microfluidization, and detergent lysis are particularly preferred. While the viral vector particles typically will autolyse the cells after a period of time, autolysis is preferably avoided by manually lysing the cells prior to autolysis.

[00135] Liquid shear cell lysis can be accomplished by any suitable technique. Examples of suitable devices for shearing cells by liquid shear include micro fluidizers and impinging jets. Microfluidizers passage the cells at high velocity through small diameter tubes. Impinging jets employ high velocity impingement of two fluid streams. [00136] In a preferred embodiment, particularly where the viral vector particles are adenoviral vector particles, the viral vector particle-infected cells are lysed using microfluidization. The harvested cells are sterilely loaded into the microfluidizer chamber (e.g., using an SCD connector and tubing or sterilized steam block connector as described elsewhere herein). While any suitable cell solution can be loaded into the microfluidizer, preferably the cell density of the cell culture solution is about 1 x 10⁴-2 x 10⁸ cells/mL. More preferably the concentration ofthe cell culture is about 1 x 10⁵-2 x 10⁷ cells/mL. Ideally, the concentration ofthe cell culture is about 1 x 10⁶-2 x 10⁶ cells/mL. The specific pressure during microfluidization lysis can be any suitable pressure. Preferably, the specific pressure is about 500-1500 psi (pounds per square inch), more preferably about 650-1350 psi, even more preferably about 800-1200 psi, and advantageously about 900-1100 psi. Ideally, the specific pressure is about 1000 psi. The flow rate in any particular microfluidization system is proportional to the specific pressure. While the flow rate during microfluidization can be any suitable flow rate, a prefeπed flow rate in a particular microfluidization system that coπesponds to the prefeπed specific pressure is about 1.5-2.5 L/min (liters/minute) (e.g., about 2 L/min). Higher flow rates can be achieved without substantially affecting the desired pressure using techniques described further herein. The temperature during microfluidization can be any suitable temperature. Preferably, the temperature is about 0-50° C. Preferably the cells are lysed in the microfluidizer in a period of about 40 minutes or less, more preferably in about 30 minutes or less, even more preferably about 25 minutes or less, and advantageously about 20 minutes or less. [00137] Any suitable amount of harvested cells can be subjected to microfluidizer lysis at any suitable flow rate. For particularly large scale preparations, a flow rate of at least about 4 L/min, at least about 6 L/min, at least about 8 L/min, at least about 10 L/min, or even higher (e.g., about 10-20 L/min) can be attained without changing the aforementioned microfluidization pressures by linking in parallel a series of microfluidizers, preferably in a closed system linked to the cell harvest container and container downstream ofthe microfluidizer through a closed transfer system such as SCD connection tubing or sterilized steam block connectors (which may be used in combination with transfer promoting devices, such as one or more peristaltic pumps).

[00138] After the harvested cells have been lysed (processed) by the microfluidizer, the microfluidizer is preferably rinsed in order to obtain the highest product yield possible. The microfluidizer can be rinsed with a suitable sterilized buffer. Suitable buffers in this respect are known in the art and include sterile water, phosphate buffered saline, sodium phosphate, sodium sulfate, and Tris buffer. A preferred buffer in this and other contexts ofthe present invention are Tris buffers (e.g., 25mM Tris, lOmM NaCl, 5 mM MgCl₂, 0.0025% polysorbate 80, pH 7.5-8), which is optimal for digestion with benzon nuclease (RNAse/DNAse - described further herein) and is capable of maintaining a pH at a range of temperatures used in the production and storage ofthe viral vector composition that is compatible with retaining the activity of viral gene transfer vectors (particularly adenoviral gene transfer vectors).

[00139] Another advantageous technique for lysing the viral vector particle infected cells is detergent lysis. Detergent lysis can be performed as an alternative, or in addition to, any ofthe aforementioned techniques, such as microfluidization lysis. Any suitable detergent in any suitable concentration can be used to lyse the viral vector infected cells. [00140] The detergent can be a denaturing or non-denaturing detergent. Examples of suitable denaturing detergents include anionic detergents, such as sodium dodecyl sulfate (SDS), or cationic detergents, such as ethyl trimethyl ammonium bromide. Denaturing detergents disrupt membranes and denature protein by breaking protein-protein interactions. Non-denaturing detergents include non-anionic detergents, such as Triton® X-100 (octylphenoxypolyethoxy-ethanol), bile salts, such as cholates, and zwitterionic detergents such as CHAPS. Zwitterionic detergents contain both cationic and anion groups in the same molecule. Non-denaturing agents, such as Triton® X-100 (octylphenoxypolyethoxy- ethanol), bind to the hydrophobic parts of proteins. Triton® X-100 (octylphenoxypolyethoxy-ethanol) and other polyoxyethylene non-anionic detergents disrupt protein-lipid interactions, but are much gentler and capable of maintaining the native form and functional capabilities ofthe proteins. Accordingly, such detergents are prefeπed, particularly where the viral vector particle is an adenoviral vector particle. Examples of , such prefeπed detergents include, but are not limited to, Tween® 20 (polysorbate 20), Tween® 40 (polysorbate 40), Tween® 80 (polysorbate 80), NP-40®, Brij® detergents, Triton® X-100 (octylphenoxypolyethoxy-ethanol), Triton® X-114, Big CHAP, deoxy-Big CHAP, Zwittergent®, and CHAPS. Preferably, the detergent used for cell lysis is Triton® X-100 (octylphenoxypolyethoxy-ethanol) or Tween® 80 (polysorbate 80). Ideally, the detergent consists essentially of (or is) octylphenoxypolyethoxy-ethanol. Such detergents can be used in any suitable concentration. Preferably, the concentration ofthe detergent is about 0.01-l%o (v/v). More preferably, the concentration is about 0.1-1% (v/v). Ideally, the concentration is about 0.1% (v/v). In some contexts, multiple detergents can be used (e.g., a combination of at least two, three, or more ofthe aforementioned detergents can be used). [00141] Alternatively, the amount of detergent used to lyse the cells can be characterized on the basis ofthe percent or factor ofthe critical micelle concentration (CMC) present in the composition. The detergent can be present in any suitable percentage or factor ofthe CMC. Examples of amounts of detergent based on percent or factor of CMC that can be used to lyse cells are described in, e.g., International Patent Application WO 97/25072 and U.S. Patent 6,165,779. The amount of Triton X-100 used to lyse the cells desirably is about 0.66X-66X CMC, and more preferably about 0.33-33X CMC, and most favorably about 6X-7X CMC. This corresponds to a molar concentration of Triton-X- 100 of between about 0.165mM-16.4mM.

[00142] The viral vector-infected cells can be maintained in the detergent composition for any suitable length of time at, for example, any ofthe above-described concentrations that result in a suitable amount of cell lysis. Preferably, the cells are maintained in the detergent composition for about 10-30 minutes. More preferably, the cells are maintained in the detergent composition for about 12-25 minutes. Ideally, the cells are maintained in the detergent composition for about 15-20 minutes.

[00143] During cell lysis, preferably at least about 70% of cells are lysed. More preferably, at least about 80% of cells are lysed. Most preferably, at least about 90% of cells are lysed. Ideally, at least about 95% of cells are lysed, and optimally, about 100% of the cells are lysed.

[00144] Where lysis ofthe viral vector particle infected cells is accomplished through detergent lysis, the detergent is desirably removed, or the concentration of detergent desirably reduced significantly during further processing ofthe viral vector particle composition. Removal ofthe detergent can be accomplished in a number of ways including, but not limited to, dialysis, diafiltration, ion exchange or gel filtration chromatography, and density gradient centrifugation. Dialysis works well with detergents that exist as monomers, but is not as effective with detergents that aggregate to form micelles, since the micelles are too large to pass through dialysis tubing. Accordingly, for micelle-forming detergents, ion exchange chromatography is favored for removing the detergent (or at least reducing the concentration thereof in the viral vector particle composition). In such techniques, the detergent-treated cell lysate is applied to an ion exchange chromatography column and the column is then washed with a suitable detergent- free buffer. The detergent will be removed as a result ofthe equilibration ofthe buffer with the detergent solution. Alternatively the protein solution may be passed through a density gradient. As the protein sediments through the gradients the detergent will be removed due to the chemical potential. A prefeπed method for the removal of detergents is filtration, ideally, diafiltration. In diafiltration, the viral vector particle composition with detergent is applied to a filter, preferably an ultrafilter using tangential flow filtration, while a detergent- free buffer is added at a rate such that the detergent is removed or reduced in concentration to a desired level. The detergents are filtered from the viral composition and the volume of the viral solution is kept constant by addition ofthe detergent-free buffer. [00145] In some aspects, it is desirable that the detergent used to lyse the cells is retained in some proportion throughout the production process and possibly even in the final viral vector particle composition. For example, where the viral vector particles are adenoviral vector particles, the adenoviral vector particle infected cells are desirably lysed in about 0.5- 2% (wt./vol.) nonionic non-denaturing detergent (preferably, polysorbate 80) to obtain a lysate, and the amount of polysorbate 80 is reduced (using any ofthe techniques described herein or their suitable equivalent in the art) to obtain a composition comprising the nonionic surfactant in a concentration of about 0.001-0.015% (wt./vol.). [00146] The viral vector particle compositions ofthe invention, including, particularly and preferably, the viral vector particle infected cell lysate can be desirably subjected to clarification, (i.e., the removal of large particulate matter, particularly cellular components, from the cell lysate by filtration). Clarification can be accomplished by any suitable technique. Suitable techniques include, but are not limited to, microfiltration and depth filtration. Both techniques use filters to separate large particulate matter (which is retained by the filter) from the viral vectors (which pass tlirough the filters). The microfiltration filter or filters can be formed from any suitable materials. Typically, the microfiltration filter is prepared from an inert (i.e., non-adenoviral-binding), polymeric material (e.g., cellulose acetate, polyester, polypropylene, PTFE, glass fiber, and nylon 66). Alternatively, the microfiltration filter can be formed from glass, ceramic materials, and even metal. Examples of suitable filters formed of such materials are known in the art, and are generally described in, e.g., Sinclair, The Scientist, 12(19), 18 (1998), FILTRATION IN THE BIOPHARMACEUTICAL INDUSTRY, Meltzer and Joraitz, Eds., (Marcel Dekker, Inc. 1998), PROTEIN PURIFICATION: PRINCIPLES AND PRACTICE, 3^rd Ed., Scopes (Springer-Verlag New York, Inc. 1994), and BIOPROCESS ENGINEERING: SYSTEMS, EQUIPMENT, AND FACILITIES, Lydersen, et al., Eds. (John Wiley and Sons, Inc. 1994).

[00147] Examples of suitable inert polymeric filter materials include cellulose acetate, polyester, polypropylene, PTFE, glass fiber, and nylon 66. These materials can also be combined (e.g., a cellulose acetate filter can be combined with a polypropylene pre-filter, a PTFE filter can be combined with a polypropylene pre-filter, a glass fiber filter can be combined with a polypropylene pre-filter, a nylon 66 filter can be combined with a polypropylene pre-filter, a cellulose acetate filter can be combined with a glass fiber pre- filter). The filter may also include diatomaceous earth, perlite, or precipitated silica, which are useful in the removal of surfactants (lipids and/or detergents), DNA, or both. [00148] In aspects where a depth filter is used during clarification, the depth filter can be any suitable depth filter. Suitable depth filters are known in related arts. Materials for the depth filter include polypropylene, cellulose, acrylics, and glass fibers. Briefly, a depth filter consists of a network of fibrous or granular materials that produce a random porous structure that traps particles in a fluid passing through the filter. The pore size ofthe depth filter is not typically rated, unlike membranes with pores of defined and ordered structures (see, e.g., FILTRATION IN THE BIOPHARMACEUTICAL INDUSTRY, Meltzer and Jomitz, Eds. (Marcel Dekker, Inc. 1998)). Preferably, the depth filter removes at least about 90% of particles of a specified size. Depth filters typically filter particles of about 0.5-100 μm. Depth filters can be derivatized, for example by the addition of a positive or a negative charge to the filter membrane by any suitable cationic or anionic composition, or by the addition of a binding moiety that is selective for a desired biomolecule to be bound by the depth filter (e.g., a lipid-binding moiety such as tri-n-butyl phosphate (TNBP)). [00149] The clarification filtration system ofthe invention can comprise any suitable number of filters having any suitable pore size. Preferably, the clarification filter will comprise pores with a pore size (approximate diameter) of about 20 μm (e.g., a 0.22 μm filter) to about 0.45 μm. More preferably the pore size is between about 10 μm and about 0.65 μm. Ideally, the average pore size ofthe filter is between about 8 μm and about 0.8 μm. Additional prefeπed combination clarification filters are described further herein. [00150] In a preferred embodiment ofthe present invention, the cell lysate is clarified by an active microfiltration (e.g., filtration through a microfiltration filter at a positive flow rate generated by any suitable technique). Any suitable flow rate can be applied in performing microfiltration clarification ofthe viral vector particle composition. The flow rate is preferably between about 700-1500 mL/min and more preferably the flow rate is about 900- 1300 mL/min per filter. Most preferably, the flow rate is about 1000-1200 mL/min per filter.

[00151] Microfiltration also can be characterized on the basis ofthe specific pressure of the microfiltration process. Any suitable specific pressure can be used. The specific pressure is typically and preferably about 0-10 psi. More preferably, the pressure is about 2-8 psi. Most preferably, the specific pressure is about 4-6 psi.

[00152] Microfiltration in the context ofthe present invention can be performed at any suitable filtration volume. The filtration volume during microfiltration is preferably at least about 10L/ft² per filter. More preferably, the filtration volume is at least about 20L/ft²per filter. Most preferably, the filtration of volume is at least about 40L/ft²per filter. [00153] Microfiltration (e.g., clarification microfiltration) can be performed at any suitable filtration flow rate. The filtration flow during clarification is preferably at least about 2L/min/ft² per filter. More preferably, the filtration flow is at least about 4L/min/ft² per filter. A filtration flow of at least about 10L/min/ft² per filter typically will be optimal. [00154] In an especially prefeπed method, the cell lysate is passed through a series of at least two, more preferably at least three, microfiltration filters having decreasing pore size in the order in which they are contacted with the cell lysate. In a particularly preferred aspect, the cell lysate is passed through a triple-microfluidization filter apparatus comprising a first filter having an average pore size of about 8.0 μm, a second (based in order of filtering by the apparatus) filter having an average pore size of about 3.0 μm, and a third filter having an average pore size of about 0.8 μm. Such triple-microfiltration filter clarification filtration can be performed at any suitable point in the viral vector particle composition purification process. Desirably, such clarification filtration is performed on the viral vector particle cell infected lysate before the filtered lysate is subjected to concentration and/or benzon nuclease digestion and additional downstream processing steps (e.g., high salt and/or organic solvent tangential flow diafiltration and chromatography purification, as described elsewhere herein). Single microfiltration filter clarification can be prefeπed in other points in the purification process. For example, when a hold step is employed (as is further described herein), such as when equipment in the next stage ofthe purification process is desirably checked for operability and/or the suitability ofthe viral vector composition is assayed (e.g., using any ofthe quality control assays described herein, such as, e.g., adventitious viral PCR assays), the viral vector particle composition will desirably be subject to clarification filtration using a filter having an average pore size of about 0.25 μm. Alternatively or additionally, after chromatography purification ofthe viral vector particle composition (e.g., after purification ofthe viral vector particle composition (i.e., enrichment of viral vector particles in at least a portion of a portion ofthe composition) by one or more ion exchange chromatography columns and at least one size-exclusion chromatography columns (possibly in combination with purification by other chromatography columns as described herein), the purified viral vector particle composition is desirably subjected to bulk filtration using a microfiltration filter having an average pore size of about 0.45 μm.

[00155] Clogging and fouling during filtration can result in a reduced yield ofthe filtered composition. In clogging, particles become physically wedged (or otherwise lodged) into the pores ofthe filter, either substantially or effectively eliminating flow through that path or reducing the size ofthe channel. In fouling, particles and dissolved material bind to the matrix ofthe filter itself, narrowing the path and changing the filtration characteristics. Either of these processes will reduce flow through the filter and alter the nature of material that is retained. The effects of these phenomena can be reduced by choosing an appropriate flow geometry and filter type (see, e.g., Sinclair, The Scientist, 12(19), 18 (1998) for discussion of such principles). In the present invention, using the series of microfiltration filters (8.0, 3.0, and 0.8 μm filters) during clarification, about 20 L of cell lysate per ft² of clarification filter can be filtered. Larger volumes will require larger filters. For example, to process about 100 L of cell lysate requires about 6.5 ft² filters in these steps, providing a ratio of about 15.5 L/ ft . [00156] As it is the density of cells that produces the lysis debris that fouls the filters, in the present invention, the filters are preferably scaled (filter sizes selected) according to (proportional to) cell number at harvest rather than volume ofthe composition to be filtered, which typically is used in the prior art. Filters desirably are tested at the highest cell density appropriate for filtration using such calculations, and thus over-scaled for clarification filtration. Preferably, the cell density prior to filtration ofthe cell lysis solution in this respect is about 1 x 10⁴-2 x 10⁸ cells/mL. More preferably the cell density in the culture prior to lysis is about 1 x 10⁵-2 x 10⁷ cells/mL. Ideally, the cell density ofthe culture prior to lysis is about 1 x 10⁶-2 x 10⁶ cells/mL.

[00157] The viral vector particle composition also or alternatively can be subjected to ultrafiltration. Ultrafiltration can be used to filter and/or purify the adenoviral vector particle composition in any suitable manner. By purify, it is meant that the composition is enriched with respect to viral vector particles by increasing the concentration of viral vector particles with respect to the total composition and/or one or more undesired biomolecules therein. Preferred uses of ultrafiltration systems in the inventive method include using ultrafiltration filters, preferably tangential flow filtration ultrafiltration systems, during buffer exchange (diafiltration) and/or during concentration ofthe viral vector particle composition. Concentration refers to the enrichment ofthe composition for viral vector particles with respect do the total composition, which can be determined by measuring the increase in particle concentration (PU/mL) brought about by the removal of contaminants or extraneous composition materials (e.g., water).

[00158] While the viral vector particle composition can be concentrated using any suitable method, concentration by tangential flow filtration (TFF) is preferred. Suitable TFF techniques are known in the art. Briefly, in TFF, the viral vector particle composition flows across a membrane surface that facilitates back-diffusion of solute from the membrane surface into the bulk solution. Membranes are generally arranged within various types of filter apparatus including open channel plate and frame, hollow fibers, spiral wound modules, and tubules. A prefeπed TFF filter in the method ofthe present invention is a hollow fiber TFF filter. Hollow fiber filters have best packing density when compared to plate and frame, tubule, and spiral wound modules (e.g., about 500 to 5000 ft²/ft³). While there are no firm guidelines, hollow fibers tend to be about 0.01-0.03 inches in diameter. A suitable and prefeπed commercially available hollow fiber filter suitable in such contexts is the Sartorius AG Technologies UFP-500-C-9A ultrafiltration module. [00159] As with microfiltration (e.g., clarification microfiltration), described elsewhere herein, the ultrafiltration filter, and more particularly, for example, the TFF ultrafiltration filter or filters ofthe inventive techniques and systems can have any suitable pore size. Preferably, the pore size ofthe ultrafiltration filter membranes corresponds with a nominal molecular weight cutoff (NMWCO) of about 30-1,000 kiloDaltons (kDa). Most preferably, the NMWCO is about 500 kDa.

[00160] TFF uses liquid flow that is substantially tangential, or parallel, to the membrane surface so that a sweeping action slows the fouling ofthe membrane. Similar to the filters used for clarification, the TFF filters used for concentration and diafiltration are desirably selected based on cell number at harvest, rather than volume ofthe composition, so as to reduce clogging and fouling. For example, in the present invention, the scale ofthe TFF filter(s) is desirably about 2.75 x 10¹⁰ cells per square meter of TFF membrane area. [00161] Ultrafiltration (UF) designates a membrane separation process, driven by a pressure gradient, in which the semi-permeable membrane fractionates components of a liquid as a function of their solvated size, structure, and charge. Ultrafiltration is gentle and efficient, and can simultaneously concentrate and desalt solutions. Ultrafiltration membranes typically have two distinct layers: a thin (about 0.1-1.5 μm), dense skin with a pore diameter of about 10-400 angstroms and an open substructure of progressively larger voids which are largely open to the permeate side ofthe ultrafilter. Any species capable of passing through the pores ofthe skin can therefore typically freely pass through the membrane. For maximum retention of solute, a membrane is selected that has a nominal molecular weight cut-off well below that ofthe species being retained. In the present invention, a prefeπed ultrafilter has a NMWCO of about 500 kDa. [00162] Diafiltration is a method of buffer exchange based on filtration. The use of ultrafiltration filters during diafiltration can facilitate the removal and exchange of salts, organic solvents, sugars, non-aqueous solvents, promote separation of free material from bound species, promote removal of material of low molecular weight, and/or facilitate the rapid change of ionic and pH levels. Preferably, diafiltration results in the removal of (or reduction in concentration of) at least one undesired biomolecule in the composition, such as contaminating, non-viral encapsidated DNA and/or undesired viral vector particles, such as adventitious non-adenoviral vectors in a composition of adenoviral vector gene transfer vector particles. Microsolutes are removed most efficiently by adding solvent to the solution being ultra-filtered at a rate equal to the ultrafiltration rate. This washes microspecies from the solution at constant volume, purifying the retained species. [00163] The shear rate during diafiltration can be any suitable shear rate (e.g., about 2,000-10,000 sec^'1). Preferably, the ultrafiltration shear rate is about 4,000-32,000 sec^"1. More preferably, the shear rate is at least about 10,000 sec^"1 (e.g., about 10,000-32,000 sec^{" l}), and even more preferably (at least in some aspects), the shear rate is at least about 12,000 sec^"1, at least about 15,000 sec^"1, or even higher (e.g., about 20,000 sec^"1). Most preferably, the shear rate is about 15,000-32,000 sec^"1. In most aspects, the shear rate will optimally be about 18,000 sec^"1. The flow rate in any particular microfluidization system is proportional to the shear rate. Therefore, a preferred flow rate is one which corresponds with a preferred shear rate. '

[00164] Ultrafiltration (e.g., TFF diafiltration ultrafiltration) can be performed at any suitable transmembrane pressure (TMP). TMP will typically and preferably be about 1-3 bar. More preferably, the TMP will be about 1.5-2.5 bar. Most preferably, the TMP will be about 2 bar.

[00165] The viral vector particle composition desirably is subjected to at least one nuclease digestion, such that the amount (concentration) of contaminating (i.e., undesired), non-viral encapsidated polynucleic acids (e.g., extraneous host cell DNA) is reduced. Any nuclease or combination of nucleases which have DNAase activity, RNAase activity, both DNAase activity and RNAase activity, or that otherwise function to reduce the amount of nucleic acid contaminants in the cell lysate without significant loss of viral activity can be added to the viral vector particle composition. The nuclease is preferably an endonuclease. An example of a prefeπed nuclease is benzon nuclease, which originates from Serratia marcescens and exhibits a high level of DNAase and RNAase activity. Benzon nuclease hydrolyzes nucleic acids into nucleotides, oligonucleotides, or smaller nucleic acid fragments. Benzon nuclease is marketed under the trademark, Benzonase® (Merck & Co, Inc, Whitehouse Station, NJ) and is described in, e.g., U.S. Patent 5,173,418. [00166] Benzon nuclease digestion can occur at any suitable stage ofthe purification process. A preferred time for the benzon nuclease treatment is after cell lysis, clarification ofthe resulting cell lysate with at least one clarification filter (e.g., at least one microfiltration clarification filter, preferably after clarification filtration using a two-part or three-part microfiltration filter system, having multiple filters of decreasing pore size as described elsewhere herein), and concentration (e.g., a concentration filtration which results in a composition about 5-10 times more concentrated than the clarified cell lysate with respect to the viral vector particles), which typically is accomplished by tangential flow diafiltration. Before addition ofthe benzon nuclease, a suitable benzon nuclease buffer is preferably added to the lysed, clarified, and concentrated viral vector particle composition using diafiltration with tangential flow filtration. While any suitable buffer can be used during the benzon nuclease treatment, the buffer preferably has an ionic strength of about 10-75mM. More preferably, the buffer has an ionic strength of about 40mM. Even more preferably, the buffer has ionic strength of about 30mM. Most preferably, the buffer has ionic strength of 20mM. Ideally, the buffer has an ionic strength of lOmM. The ionic strength is desirably obtained by the presence of a monovalent salt in the composition, such as NaCl, which is prefeπed.

[00167] Once the viral vector particle composition buffer is replaced with benzon nuclease buffer, the benzon nuclease is added to the composition. Any suitable amount of benzon nuclease can be used for non-viral encapsidated polynucleotide digestion. In the present invention, the amount of enzyme to be used in the polynucleotide digestion is determined (and is proportional to) the number of cells at harvest rather than the volume of the composition, which is the standard in the art. Application of an amount of benzon nuclease based on the number of cells at harvest typically results in higher levels of non- viral encapsidated DNA digestion during benzon nuclease digestion. The amount of nuclease added to the viral supernatant is preferably about 0.5-1.5 U per about every 2 x 10³-2 x 10⁵ cells, and most preferably about 0.5-1.5 Uper about every 2 x 10⁴ cells. [00168] The combination of benzon nuclease and the viral composition ("the reaction") can be incubated at any suitable temperature for any suitable amount of time which results in a decrease in the amount of nucleic acid contaminants. Suitable conditions for the benzon nuclease digestion include digestion at room temperature (about 18-25° C) for about 1-4 hours, or overnight at refrigerated temperatures (0-10° C). In a prefeπed embodiment ofthe invention, the benzon nuclease digestion is performed at at least about 30° C, more preferably at about 34-36° C, for about 4 hours. Optimally, the digestion is performed at about 35 ° C for about 4 hours. It was previously thought that incubation ofthe virus at high temperatures would deactivate the virus. However, the inventors have suφrisingly found that following the incubation ofthe reaction at about 35° C, greater than about 90% ofthe viral vector particles remain active (as compared with the activity ofthe viral vector particles before the reaction). The results of benzon nuclease digestion experiments at this temperature in conjunction with viral vector activity assays are provided further herein. [00169] The benzon nuclease digestion is desirably conducted in an environmentally closed system linked to or comprising both the container or device used prior to the benzon nuclease digestion, which typically and preferably will be a tangential flow diafiltration system used for benzon nuclease buffer exchange, and the container or device used after the benzon nuclease digestion is completed, which typically and preferably is another tangential diafiltration system. It is possible that the first and second containers are the same container or device, although such embodiments are not typical. An environmentally isolated (i.e., "closed") system means that the system of components forming the system (devices and/or containers and connecting passageways (which typically are formed of sterile SCD connections and/or steam sterilized steam block connections)) are isolated from, and impermeable to, adventitious microorganisms and viruses. Additional closed system aspects ofthe invention are described further herein. In the context ofthe benzon nuclease digestion, the digestion can be performed in, for example, a passageway positioned between the benzon nuclease buffer exchange tangential flow filtration system and the post-digestion buffer exchange tangential flow filtration systems or in either one ofthe tangential flow filtration devices. The reaction conditions for the digestions in the closed system are preferably monitored and controlled by one or more automated reaction condition monitors. For example, an automated programmable temperature monitor typically is used to maintain digestion temperatures at the desired temperature (e.g., about 35° C) in the closed system for the duration ofthe reaction. Examples of using such monitoring and control systems are further described herein. Any suitable combination of reaction conditions (e.g., temperature) can be monitored and adjusted automatically, as appropriate. [00170] The benzon nuclease digestion performed under the above-described conditions and using the above-described techniques results in a significant reduction in the level of non-viral encapsidated polynucleotides, and, particularly non-viral encapsidated DNA, in the viral vector particle composition. Particularly, using the aforementioned techniques and conditions, a reduction in the amount of non- viral encapsidated DNA (with respect to the amount prior to benzon nuclease digestion, e.g., in the viral vector particle infected cell crude lysate) of at least about 2 logs, preferably at least about 3 logs, more preferably at least about 4 logs can be achieved. Indeed, the methods ofthe present invention, particularly when such benzon nuclease digestion techniques are combined with high salt and or organic solvent filtration (as described herein), or other suitable techniques described herein which reduce the concentration of non- viral encapsidated DNA in the composition (e.g., negative chromatography techniques using one or more chromatography columns having a binding moiety more selective for non-viral encapsidated DNA than for viral vector particles) can be used to achieve a reduction in non- viral encapsidated DNA of about 5 logs, about 6 logs, or even about 7 logs with respect to the amount of non- viral encapsidated DNA in the composition at a stage prior to benzon nuclease digestion. [00171] Benzon nuclease digestion ofthe viral vector particle composition can be performed any suitable number of times. Typically and preferably in most aspects, the purification of viral vector particles by the inventive method comprises only one benzon nuclease digestion. Alternatively, multiple (e.g., 2, 3, or more) benzon nuclease or benzon nuclease/other nuclease digestions can be performed using any suitable combination of techniques described herein or otherwise known in the art.

[00172] Non- viral encapsidated polynucleotide and undesired non- viral vector component biomolecules (e.g., non-viral vector component protein and/or lipid biomolecules) can be further removed by organic solvent filtration, lipid removal chromatography, and/or high salt filtration techniques. The present invention provides methods of preparing purified adenoviral vector particle compositions using such techniques alone or in combination with any ofthe other production and purification techniques described herein. [00173] Incubating the viral vector particle composition with a suitable organic solvent can reduce the amount of non- viral encapsidated DNA in the composition, reduce the amount of non- viral vector component lipids in the composition, de-activate adventitious enveloped viral vector particles present in the composition, or accomplish any combination thereof. The organic solvents used during such incubation, and preferably associated diafiltration, can be any suitable organic solvents which result in the removal of an undesired biomolecule (e.g., lipid, non-viral encapsidated DNA, and/or non-viral protein), deactivation of adventitious enveloped virus particles, or both. Suitable organic solvents include, but are not limited to, -C₆ alcohols (e.g., ethanol, isopropanol), which are prefeπed for reducing DNA- viral vector particle interactions, and tri-n-butyl phosphate (TNBP), which is preferred for reducing lipid-viral vector particle interactions. Thus, for example, the invention provides in one aspect, a method wherein a suitable organic solvent is added to the viral vector particle composition such that hydrophobic interactions between non- viral encapsidated polynucleotides, particularly DNAs, and the viral vector particles are reduced. The binding of polynucleotides to the viral vector particles and related measurements (e.g., the affinity of such a reaction) can be determined by any suitable technique (e.g., gel mobility shift assay, DNAse I footprinting, and/or methylation interference assay (see, e.g., Sambrook et al. supra and Ausubel et al. supra)). [00174] In another aspect, the amount of non- viral component lipids is reduced by the addition of an organic solvent that reduces lipid-viral vector particle interactions. Any suitable organic solvent that reduces such interactions can be used. A prefeπed organic solvent in this respect is tri-n-butyl phosphate (TNBP). Viral vector particle-lipid interactions and related measurements (e.g., affinity of such interactions) can be determined by any suitable technique (e.g., gel mobility shift assay) (see, e.g., Sambrook et al. supra and Ausubel et al. supra)).

[00175] The organic solvent can be polar or non-polar. Prefeπed polar organic solvents include ethanol, isopropanol, or a combination thereof. As indicated above, a prefeπed non-polar organic solvent is TNBP.

[00176] Any suitable amount of organic solvent can be used in the organic solvent filtration methods ofthe invention. The amount of solvent will vary with the type of solvent used, the size ofthe adenoviral vector particle composition, and the desired outcome ofthe organic solvent filtration. Typically, the viral vector particle composition will be incubated and filtered in an organic solvent at a concentration of about 5-20% (v/v) (e.g., about 10-15% (v/v)).

[00177] The organic solvent can be added to the viral vector particle composition at any suitable stage ofthe purification process to form a combined composition. The combined composition is then desirably subjected to filtration, typically and preferably tangential flow ultrafiltration to obtain a filtered composition, wherein the filtered composition comprises less of an undesired biomolecule (e.g., less host cell DNA and/or less of a non- viral component lipid) than a substantially identical composition subjected to substantially identical filtration in the absence ofthe organic solvent. Alternatively or additionally, after organic solvent filtration, the filtered composition desirably comprises less active adventitious enveloped viral vector particles than a substantially identical composition subjected to substantially identical filtration in the absence ofthe organic solvent. The filtration to inactivate the undesired adventitious enveloped viral vector particles and/or remove the undesired biomolecules enriches the solution for active viral vector particles by decreasing any of these impurities.

[00178] The organic solvent filtration techniques ofthe invention can be performed at any suitable temperature. Preferably the filtration is done at room temperature (about 18-25° C). This temperature desirably is monitored and controlled using an automated programmable monitoring and control system in the container in which the organic solvent filtration is carried out (e.g., in a tangential flow filtration system) as described elsewhere herein.

[00179] In a more particular aspect, the organic solvent can be combined with surfactants to increase the inactivation of undesired, non-adenoviral, enveloped virus particles, removal of undesired polynucleotides, removal of undesired lipids, or any combination thereof. Any suitable surfactant can be used alone or in conjunction with the organic solvent to inactivate the adventitious virus particles. Prefeπed surfactants in this respect include polysorbate 80, Triton® X-100, or a combination thereof. Any suitable concentration ofthe surfactants can be used. Preferably, the surfactant is present in a concentration of about 1-3% (w/w). The surfactant(s) can be combined with any suitable organic solvent. Preferably the organic solvent is TNBP. While the organic solvent can be present in any suitable concentration, a prefeπed concentration is about 0.1-0.5 % (w/w) and most preferably about 0.3% (w/w). [00180] Alternatively or additionally, the viral vector particle composition can be subjected to a "high salt filtration" to reduce the level of non- viral encapsidated polynucleotides in the composition and/or non- viral vector particle component proteins (e.g., host cell proteins) in the composition. Any amount of a suitable salt in a suitable concentration (or suitable composition which increases the ionic strength ofthe composition to a suitable level) that detectably reduces amount of non- viral vector particle encapsidated polynucleotides in the viral vector particle composition, detectably reduces the amount of non-viral vector particle component proteins in the viral vector particle composition, or both upon suitable incubation and filtration as compared to a composition not subjected to such filtration can be used.

[00181] Any suitable composition, including, for example, a monovalent salt, divalent salt, polyvalent salt, or a combination thereof can be used to increase the ionic strength of the viral vector particle composition to a level such that the concentration of non- viral component polynucleotides and/or proteins are reduced. Where the filtration is a high salt filtration, any suitable salt can be used. The monovalent salt, divalent salt, or polyvalent salt can comprise one or more cations selected from the group consisting of Group I elements, Group II elements, and Group III elements, polyatomic cations, and one or more counteranions. Polyatomic cations are known in the art and include ammonium, alkylammonium, dialkylammonium, trialkylammonium, tetraalkylammonium, and triarylphosphonium. Similarly, counteranions are known in the art and include fluoride, chloride, bromide, iodide, nitrate, sulfate, phosphate, trifluoromethanesulfonate, acetate, carbonate, acetylacetonate, oxalate, tartrate, and succinate. It is preferable that the salt is water-soluble.

[00182] Preferably, the salt is a monovalent or divalent salt. Suitable salts in this respect include NaCl, MgCl₂, MgSO₄, and CaCl₂. More preferably, the salt is monovalent. An especially prefeπed salt for high salt filtration is NaCl. The salt can be present in any suitable concentration during the filtration. Preferably, the salt is present in a concentration of about 0.5-1.2M. The ionic strength ofthe composition after addition ofthe salt (or other suitable ionic strength increasing substance) can be any suitable ionic strength. Preferably, the ionic strength is about 0.5-1.2M.

[00183] "High salt filtration" can be done at any suitable temperature. Preferably the filtration is done at room temperature (18-25° C). This temperature desirably is monitored and controlled using an automated programmable temperature system in the container where the high salt filtration is carried out (e.g., in a tangential flow filtration system). [00184] Thus, for example, the invention provides a method of preparing a purified viral vector composition, comprising increasing the ionic strength ofthe composition to at least about 0.5 M to form an increased ionic strength composition, and subjecting the increased ionic strength composition to tangential flow filtration to obtain a filtered composition, wherein the filtered composition comprises less non-viral-encapsidated DNA, non- viral vector particle component protein, or both, than a substantially identical composition subjected to substantially identical tangential flow filtration at a lower ionic strength. [00185] Filtration of a solution with both increased ionic strength (or salt concentration) and an effective amount of one ofthe above-described organic solvents can be used in the preparation of a purified viral vector composition to decrease the amount of an undesired biomolecule, undesired active adventitious enveloped viral vector particle, or both in the viral vector particle composition. Since organic solvents and high salt concentrations typically are incompatible, when the two are combined, the ionic strength ofthe composition preferably is about 0.5-10 mM. Most preferably, the ionic strength in such methods is about lOmM. The concentration ofthe organic solvent can be any suitable concentration (e.g., about 5-20% (v/v), and preferably about 20% (v/v)). Preferably, the organic solvent in such methods is a C Cβ alcohol, such as ethanol, isopropanol, or a combination thereof.

[00186] It is preferable that the production purification process of adenoviral vectors includes one or more steps of maintaining the lysate, filtered lysate, and/or purified stock in a temporary storage composition. During a large-scale production/purification process, stably storing the viral vectors can allow time to temporarily stop the production process to test or fix the production equipment. Additionally, stopping the production/purification process allows time for the testing ofthe viral vector particle composition at intermediate stages. This premature testing procedure allows the detection of contaminants (e.g., non- viral encapsidated DNA, adventitious viruses) before the final product has been obtained. This can result in the saving of time and money if the intermediate product is faulty, and allows the artisan the option of determining whether to proceed with the production purification process.

[00187] This storage composition maintains the viral activity ofthe virus for an extended period of time. Preferably, the viral vectors are maintained in the temporary storage composition for at least about 3 hours. Preferably, the viral vectors are maintained in the storage composition for about 3 hours-40 days. It is preferable that at least about 70% of the viral vector particles in viral vector particle composition (e.g., the lysate, filtered lysate, and/or purified composition) are active at the end ofthe period. More preferably, at least about 80% ofthe viral vector particles in the composition are active at the end ofthe period. Most preferably, at least about 90% ofthe viral vector particles in the composition are active at the end ofthe period.

[00188] The temporary storage composition comprises about 1-25% (wt./vol.) trehalose, about 0.001-0.015% nonionic surfactant, about 10-65mM arginine, or a combination thereof, hi the context ofthe present invention, trehalose functions as a stabilizer ofthe non-enveloped viral vector particles. Trehalose (α-D-glucopyranosyl α-D-glucopyranoside dihydrate) is known in the art and described in, for example, U.S. Patents 6,225,289 and 4,891,319. Preferably, the temporary storage composition comprises about 1% to 20% (wt./vol.) trehalose. More preferably the temporary storage composition comprises about 2- 15% trehalose, and even more preferably, the temporary storage composition comprises about 3-10% trehalose. Most preferably, the temporary storage composition comprises about 4-6% trehalose. Ideally, the temporary storage composition contains about 5% trehalose.

[00189] In another prefeπed embodiment, the temporary storage composition further comprises a nonionic surfactant in a concentration of about 0.001-0.015% (w/v). Preferably, the nonionic surfactant is in a concentration of about 0.0015-0.01% (w/v) and more preferably about 0.0018-0.007% (w/v). Even more preferably, the nonionic surfactant is in a concentration of about 0.0021 -0.005% (w/v). Still more preferably, the nonionic surfactant is in a concentration of about 0.0027% to 0.005% (w/v). Ideally, the nonionic surfactant is in a concentration of about 0.0025% (w/v). A prefeπed nonionic surfactant in the context ofthe present invention is polysorbate 80 (also known as Polyoxyethylene (20) sorbitan monooleate, Tween® 80, and PEG-3/6 sorbitan oleate). Polysorbate 80 exhibits stabilizing effects on non-enveloped viral vectors both in the presence and absence of trehalose and in the presence of divalent metal salts, cationic polymers, or a combination thereof. Other nonionic surfactants are well known in the art, and include, for example, NP- 40, Brij detergents, Big CHAP, Triton X-100, C12E8, Octyl-β-D-glucopyranoside, Pluronic F68, and polysorbate 20.

[00190] Optionally, the temporary storage composition further comprises about 10-65 mM arginine to further promote stability of non-enveloped viral vectors. Preferably, the concentration of arginine is about 25-55 mM. More preferably, the concentration of arginine is about 30-50 mM. Even more preferably, the concentration of arginine is about 35-45 mM. Ideally, the concentration of arginine is about 40 mM. [00191] Additionally, the temporary storage composition can comprise about 0.05-2 mM of a divalent metal salt, a cationic polymer, or a combination thereof. Divalent metal salts are well known in the art and include, for example, calcium chloride, magnesium chloride, and magnesium sulfate. In a preferred embodiment, the composition comprises about 0.7 to about 1.3 mM divalent metal salt. Still more preferably, the composition comprises about 0.9 to 1.1 mM divalent salt. The prefeπed divalent salt is a magnesium salt, such as magnesium chloride or magnesium sulfate. Magnesium chloride (MgCl₂) is exceptionally effective in preserving viral vectors, however it has been reported that MgCl₂ may have a destabilizing effect on some viruses (e.g., Wallis et al., Virol, 26, 694-699 and Habili et al., Virol,. 60, 29-36 (1974)). In these cases, the viruses destabilized by MgCl₂ may be stabilized by magnesium sulfate. As such, in an alternative prefeπed embodiment, the magnesium salt is magnesium sulfate.

[00192] Cationic polymers that are useful in biological preparations are well known in the art. Examples of biologically useful cationic polymers include, but are not limited to, polylysine, polyethyleneimine, polytrimethylaminoethyl methacrylate, poly(4- vinylpyridinium), diethylaminoethyl (DEAE)-dextran, poly(acrylic acid), poly(amidoamine), poly(N-(2-hydroxypropyl)methylacrylamide), poly(dimethylaminoethyl methylacrylate), polyethylene glycol, poly(N-ethyl-4-vinyl pyridinium bromide), poly (trimethylammonioethyl methacrylate chloride), poly(vinylalcohol), poly(N-ethyl-4- vinylpyridinium bromide), and polyvinylsulfonate.

[00193] The step of maintaining the temporary composition (e.g., the stored lysate, filtered lysate, and/or purified composition) is preferably performed at between about -80° and 50° C. The temporary storage can be carried out in a liquid composition comprising the above-described stabilizers at about 1-25° C. More preferably, the step of maintaimng the lysate, filtered lysate, and/or purified stock is performed at below about 10° C (e.g., about 0- 10° C, below about -35° C, below about -50° C).

[00194] In a prefeπed embodiment, the present invention includes the method of producing a viral vector particle composition, comprises providing a population of viral vector particle infected cells, harvesting at least some ofthe infected cells to obtain a harvested cell composition, lysing the cells ofthe harvested cell composition to obtain a lysate, enriching the lysate for viral vector particles by filtration comprising contacting the lysate with a tangential flow filtration system to obtain a filtered lysate, and subjecting the filtered lysate to chromatography purification with a chromatography system comprising at least one ion exchange chromatography column, at least one size-exclusion chromatography column, or at least one of each, to obtain a purified viral vector particle composition, wherein the method comprises maintaining the harvested cell composition, filtered lysate, or both in a storage composition, preferably at a temperature below about 10° C, for a period of at least about 3 hours, preferably, at least about 12 hours, more preferably, at least about 1 day, most preferably, at least about 3 days, ideally, at least about 7 days or longer (e.g., about 1 month) while at least about 70% ofthe viral vector particles remain active while assessing the operability of a tangential flow filtration system, the operability of a chromatography system, or both.

[00195] Assessing the operability tangential flow filtration system, the operability ofthe chromatography system, or both can comprise any suitable assessment of operability and/or performance. For example, assessing operability can include calibration ofthe pH monitor, calibration ofthe conductivity monitors, performing an automated system check of system pressure and temperature monitors, performing an automated check ofthe system pumps for flow and diaphragm integrity, performing preventative maintenance, checking part replacement logs to ensure compliance with system operating instructions, or any combination thereof.

[00196] Additionally, while the harvested cell composition, filtered lysate, or both is in the storage composition, they are preferably assessed for host cell protein concentration, non- viral encapsidated DNA concentration, number of viral particles, number of infectious viral particles, the presence of adventitious vectors, or a combination thereof. These assays can be done using any suitable techniques, including, but not limited to, mass spectroscopy (as described in, e.g., U.S. Patent 5,965,358 for adenoviral vector particles), SDS-PAGE, western blot, reverse phase HPLC, quantitative RT-PCR (e.g., TaqMan®, Perkin Elmer/ Applied Biosystems), and plaque assays, wherein the failure ofthe results ofthe assessment to meet or exceed the predetermined standards of purity results in the discarding ofthe harvested cell composition, filtered lysate, or purified viral vector particle composition, or (if acceptable) subjecting the composition to repeated and/or additional purification steps (e.g., a repeated benzon nuclease digestion). For example, in the case where the recombinant viral vector particle encodes a TNF-α, it is deleterious to the patient if the composition to be administered contains large amounts of TNF-α protein. Therefore, the harvested cell lysate, filtered lysate, and purified stock are assayed for the presence and amount of TNF-α protein, and the production lot is discarded if the lot contains more than about 1 pg TNF-α protein per 6.4 x 10⁹ total viral particles.

[00197] The temporary storage buffer is preferably added by diafiltration using tangential flow filtration. If more than one diafiltration is performed on the viral vector composition, the diafiltration with the temporary storage buffer preferably occurs last in the series, though diafiltration with the storage buffer can occur at any point in the purification process.

[00198] The temporary storage composition can be transferred to sterile containers directly following diafiltration with the temporary storage buffer. Preferably, the temporary storage composition is filtered before transfer to the sterile container. The filter can be any suitable filter. Preferably, the filter has an average pore size of about 0.45 μm. The temporary storage composition can be transfeπed at any suitable rate. Preferably, the storage composition is transferred at about 400-1000 g/min per filter. [00199] The temporary storage composition can be stored in any sterile containers. Preferably in the present invention, the transfer to the sterile containers is within a closed system. The sterile container can be any suitable container. Preferably, the temporary storage containers are flexible, sterile, disposable bags (e.g., plastic bags). Particularly prefeπed plastic bags will include fittings that are mated to the inlet and/or outlet of device(s) or container(s) used in the production and/or purification process, such that a closed seal is readily formed therebetween. Transfer out of or into the bag in a sterile manner can desirably be affected by use of seals that are breakable upon sealing engagement with the inlet/outlet ofthe associated device or container. [00200] The invention further provides a method of reducing lipid and/or surfactant concentrations in the viral vector particle composition comprising filtering a viral vector particle comprising a population of viral vector particles (e.g., adenoviral vector particles) with a filter derivatized with a composition selective for removal of lipids, surfactants, or both, with respect to other biomolecules, such that a purified viral vector particle composition is obtained. In such a method, the amount of lipids, surfactants, or both in the purified viral vector particle composition upon such filtration will be detectably less than in the viral vector particle composition prior to (or without) such filtration. Preferably, the composition selective for the removal of lipids, surfactants, or both is, or comprises, a silica. The derivatized filter preferably imparts a positive charge to the filter, which is generally a clarification microfiltration filter. Determination ofthe reduction of lipid and/or surfactant concentrations in the composition can be determined by any suitable technique. [00201] The reduction in the concentration of undesired lipids, surfactants, or both, also or alternatively can be accomplished by subjecting the viral vector particle composition to chromatographic purification (i.e., chromatographic separation ofthe composition, combined with the selective elution of a portion ofthe composition comprising a population of viral vector particles, such that the resulting eluted composition is enriched (has a higher concentration of) viral vector particles than the composition applied to the chromatography column). In such techniques the viral vector particle composition is applied to a chromatography column comprising a chromatography resin functionalized with a binding moiety selective for lipids, surfactants or both, with respect to the viral vector particles, other non-lipid biomolecules, or both (e.g., a charged silica binding moiety). At least a portion ofthe viral vector particle composition is eluted from the chromatography column (e.g., by addition of a suitable elution buffer) to obtain a chromatography purified adenoviral vector particle composition.

[00202] Thus, the present invention provides a method for preparing a purified viral vector (e.g., adenoviral vector) particle composition comprising subjecting a viral vector particle composition comprising a population of viral vector particles to a chromatography column comprising a chromatography resin functionalized with a binding moiety selective for removal of lipids, surfactants, or both, with respect to viral vector particles, other non- lipid biomolecules, or both, and eluting at least a portion ofthe composition from the chromatography column comprising a population of viral vector particles to obtain a purified viral vector particle composition. Any suitable chromatography resin exhibiting such characteristics can be employed to cany out the method. Preferably, the chromatography resin in such methods is an anion exchange chromatography resin and further desirably will comprise a silica moiety selective for lipids, surfactants, or both. Alternatively, the resin can be a gel filtration resin. In such embodiments, the gel filtration resin can comprise a binding moiety comprising at least one hydroxyl group. In this respect, it is preferred for the viral vector particle composition to comprise TNBP when the composition is subjected to the chromatography column. Any suitable concentration of TNBP can be used in this or the aforementioned aspects ofthe invention (e.g., the above- described organic solvent filtration methods). Preferably, the viral vector particle composition is purified in a composition comprising about 0.1%-5% TNBP, and, more preferably is purified in a composition comprising about 0.3% TNBP. The lipid/surfactant concentration reduction methods ofthe invention can be combined with any other suitable purification technique described herein. For example, the purification method can further comprise subjecting the purified viral vector particle composition to size-exclusion chromatography to obtain a size purified adenoviral vector composition. The size purified adenoviral vector composition can then be subjected to clarification microfiltration to obtain a bulk drug substance, which can be stored in a suitable storage formulation, such as a trehalose/polysorbate 80 formulation, particularly where the viral vector particles are adenoviral vector particles.

[00203] The viral vector particle composition can be subjected to any number of additional or alternative chromatographic purification techniques (steps) to obtain a purified viral vector particle composition. Any suitable type of chromatography column or combination of columns can be used in the purification ofthe viral vector particles. Preferably, the viral vector particle composition, particularly where the composition comprises a population of adenoviral vector particles, is subjected to one or more ion exchange chromatography columns. Preferably, the ion exchange chromatography columns comprise an anion exchange chromatography resin. The anion exchange chromatography resin can be any suitable resin. Typically and preferably, the anion exchange chromatography resin will be functionalized with a tertiary or quaternary amine-binding moiety that is more selective for adenoviral vector particles than DEAE. Examples of preferred chromatography resins in this respect are described in International Patent Application WO 99/54441.

[00204] The process of purifying a viral vector particle composition by chromatography can involve the use of any number of chromatography steps (i.e., columns) to achieve the desired purity. For example, the chromatography purification process can involve the use of a single step technique (i.e., one column), which is capable of purifying the adenoviral vector particle composition to a desired level. Preferably, however, the chromatography purification process will involve the use of multiple columns, such as two or more, three or more, or even four or more columns, to achieve the desired purity, with two and three column processes being most prefeπed. The process can include the repetition of purification by a particular type of chromatography column. For example, the method can comprise subjecting the viral vector composition to two anion exchange chromatography resins, such as a quaternary amine functionalized resin and a tertiary amine functionalized resin, as described in, e.g., the '441 PCT application.

[00205] In an exemplary three-step chromatography process, the adenoviral vector particle composition is initially subjected to a first column, which may be refeπed to as a "capture column". The capture column is characterized in that it generally is responsible for removing large particulate matter, particularly cellular components, from the cell lysate or filtered composition. The first column in such aspects can comprise any suitable resin. For example, the first column can comprise a silica-based charged membrane, a hydrophobic interaction chromatography resin, an ion exchange chromatography resin, or any combination ofthe above. Preferably, the first column will comprise an ion exchange chromatography resin (e.g., a Q resin) or hydrophobic interaction chromatography resin. Where a hydrophobic interaction chromatography resin is utilized, it is preferred that the hydrophobic interaction chromatography resin is a non-porous hydrophobic interaction chromatography resin.

[00206] The viral vector particle composition is applied to (e.g., loaded on) the chromatography column(s) using any suitable technique. In a typical multiple-column system, the first column is desirably subjected to an equilibration buffer. Generally, this buffer will comprise a monovalent or divalent salt, or a mixture of both, having a certain ionic strength and a desired molarity and pH. Preferably, the equilibration buffer will comprise a monovalent salt in a concentration of about 250-600 mM and will have a pH of between 7-9. More preferably, the equilibration buffer will comprise sodium chloride (NaCl) in a concentration of about 300 mM and will have a pH of about 7.5. After passing the equilibration buffer through the column, the viral vector particle composition is loaded and subsequently run through the column, which effectively binds the viral vector particles to the resin. A wash buffer typically is used in conjunction with running the viral vector particle composition through the column. The wash buffer generally comprises the same solution as the equilibration buffer but contains a slightly higher concentration ofthe salt. In this respect, the wash buffer will typically comprises a salt concentration within the same range as the equilibration buffer (e.g., 250-600 mM); however, at a slightly higher concentration. The pH ofthe wash buffer also is preferably in the range of about 7-9. Thus, the wash buffer preferably comprises NaCl in a concentration of about 360 mM and has a pH of about 7.5.

[00207] After the viral vector particle composition is loaded and run through the first chromatography column, a portion ofthe viral vector particle composition is eluted, such that a purified viral vector particle composition is obtained (with respect to the viral vector particle composition loaded onto the column). Elution ofthe portion can be accomplished by any suitable technique. Typically, elution is accomplished with an elution buffer that is applied to the first column, which causes a population of bound viral vector particles to be released from the column. This buffer generally comprises the same solution as the above- described buffers but with a higher salt concentration than either ofthe equilibration buffer or wash buffer. For example, an elution buffer having a salt concentration of about 400-600 mM and a pH of about 7-9 is suitable for the elution of adenoviral vector particles bound to a quaternary and/or tertiary amine functionalized ion exchange chromatography column. A prefeπed first column elution buffer in this respect will comprise NaCl in a concentration of about 475 mM and have a pH of about 7.5. [00208] The chromatography columns ofthe invention are prepared by any suitable technique. Typically, a prepared sluπy comprising the chromatography column resin is "packed" into the column using a particular packing rate. The packing rate is important during a chromatography purification process. The packing rate can be any suitable packing rate and will vary with the type of chromatography column at issue among other variables. After the column has been packed with an appropriate resin, the viral vector particle composition is loaded onto the column, run through the column, and finally eluted from the column. The rate at which the viral vector particle composition is loaded, run, eluted or (typically) the rate at which all three processes occur is referred to herein as the flow rate. Typically and preferably, the packing rate and flow rate for a capture column are between about 250-500 cm hr per column. More preferably, the flow rate used for chromatography in such a column is about 300 cm/hr and the packing rate is about 360-450 cm/hr.

[00209] A high salt buffer desirably is applied to the column to elute any remaining viral vector particles after application ofthe elution buffer and to rinse the column for any future use. Such a high salt buffer will generally comprise the same materials used in the above described buffers but will contain a higher salt concentration than any ofthe preceding buffers. The high salt buffer will desirably have a salt concentration of about 0.75-1.5 M and a pH of between about 7-9. Preferably, the high salt buffer comprises NaCl in a concentration of about 1 M and has apH of about 7.5.

[00210] Following elution from the first column, the portions ofthe eluant containing the viral vector particles are collected to obtain a purified viral vector particle composition. This eluted viral vector particle composition can then be further purified by, for example, loading the eluate onto a second column (e.g., an anion exchange chromatography column), which is referred to in the art as a purification column.

[00211] A purification column can comprise any suitable resin, however, an ion exchange chromatography resin is prefeπed. More preferably, the purification column comprises an anion exchange chromatography resin. In a typical ion exchange or anion exchange chromatography resin, the resin is a solid that has chemically bound charged groups to which ions are electrostatically bound and can exchange these ions for ions in aqueous solution. Ion exchangers can be used in column chromatography to separate molecules according to charge. Charged molecules adsorb to ion exchangers reversibly so that molecules can be bound or eluted by changing the ionic environment. Separation on ion exchangers is usually accomplished in two stages: first, the substances to be separated are bound to the exchanger, using conditions that give stable and tight binding; then the column is eluted by the addition of buffer(s) of different pH, ionic strength, or composition wherein the components ofthe buffer(s) compete with the bound viral vector particles for the binding sites on the resin. An ion exchanger is usually a three-dimensional network or matrix that contains covalently linked charged groups. If a group is negatively charged, it will exchange positive ions and is a cation exchanger. A typical group used in cation exchangers is the sulfonic group, SO₃ ^". If an H⁺ is bound to the group, the exchanger is said to be in the acid form; it can, for example, exchange one IT^1" for one Na⁺ or two H⁺ for one Ca²⁺. The sulfonic acid group is called a strongly acidic cationic exchanger. Other commonly used groups are phenolic hydroxyl and carboxyl, both weakly acidic cation exchangers.

[00212] The ion exchange purification resin will preferably be functionalized with a anion exchanging tertiary amine-binding moiety, comprising at least three carbon atoms, a quaternary amine binding moiety, or both. These binding moieties, as they are used in the context ofthe invention, will be more selective for viral vector particles than a DEAE binding moiety. Particularly prefeπed purification resins are described in the above- referenced '441 PCT application. Dimethylaminopropyl binding moieties are particularly prefeπed in the anion exchange chromatography (AEC) aspects (particularly in an AEC purification column) ofthe invention.

[00213] The binding moiety ofthe invention can be linked to a matrix support through any suitable (and desirably flexible) linker group, as is known in the art. Sulphonamide and acrylic polymer linkers are among those suitable for use in the context ofthe present invention. The support matrix can be composed of any suitable material; however, it is preferable for the matrix support to be a material based on the concept of "soft gel in a rigid shell." This "gel-filled" chromatography resin allows one to take advantage ofthe high capacity of soft gels, e.g., agarose, and the rigidity of composite materials for high flow rates and increased tolerance to compression or shrinking and swelling ofthe media, a common characteristic of soft gels. These "gel-filled" chromatography resins are well- known in the art and are described in U.S. Patent Nos. 5,268,097 and 5,672,276, for example. Moreover, it is prefeπed that the matrix support be a perfusive anion exchange chromatography resin such that intraparticle mass transport is optimized. [00214] Typical perfusive chromatography resins which can be used in the context ofthe present invention have large (e.g., about 6,000-8,000 A) pores that transect the particles. A network of smaller pores, thereby limiting diffusional pathlengths, enhances the surface area ofthe large-pore diameters. In part due to the bimodal distribution of pore sizes, the mobile phase and adenovirus enter and flow through the chromatography resin particles, utilizing both convective and diffusional transport. Such perfusive chromatography resins are more fully described by, e.g., Afeyan et al., J. Chromatogr. 519: 1-29 (1990), and U.S. Patents 5,384,042; 5,228,989; 5,552,041; 5,605,623; and 5,019,270. [00215] A particularly prefeπed anion exchange chromatography resin in the context of the present invention is POROS® 50D, commercially available from PerSeptive Biosystems (Framingham, Massachusetts). Such resins are described in the above-referenced '441 PCT application. Another desirable anion exchange chromatography resin in the context ofthe present invention, which is particularly useful as a capture column in a system comprising three or more chromatography columns is Q Ceramic HyperD™ F resin, commercially available from BioSepra, Villeneuve-La-Garenne, France and described in the above- referenced '441 PCT application.

[00216] Prior to the viral vector being loaded onto the purification column, the purification column typically is subjected to an equilibration buffer as described above. It is also contemplated to subject the viral particle composition to an anion exchange chromatography resin without first performing tangential flow filtration on the composition, diluting the composition, or de-salting the composition. The viral vector is then loaded onto the purification column, and is subsequently run through the column in conjunction with a wash buffer, as described above. The elution buffer for the purification column also can be the same or different from the one used in conjunction with the first column, however, it generally comprises a salt at a slightly higher concentration than that used for the first column. The prefeπed salt concentration (or ionic strength) for the elution buffer used in the purification column is about 450 mM.

[00217] Any suitable packing rate and flow rate can be used in conjunction with chromatography purification ofthe viral vector particle composition in the purification column. Preferably, the purification column is packed at a rate of about 600-750 cm/hr and has a flow rate of at least about 300 cm/hr. Higher flow rates also are contemplated. For example, the flow rate used in conjunction with the purification column can be at least about 400 cm/hr, at least about 500 cm/hr, or even at least about 600 cm/hr. In general, the packing rate will be at least about 125% the flow rate (e.g., about 120-150% ofthe flow rate).

[00218] Alternatively or additionally, the viral vector particle composition can be subjected to size-exclusion chromatography (SEC). The size-exclusion chromatography purification preferably is a buffer exchange step, which places the size-exclusion purified viral vector composition (i.e., the portion ofthe composition eluted from the size-exclusion chromatography column) into a different buffer, which typically and desirably will be the final formulation buffer for the viral vector particle composition.

[00219] Any suitable SEC column can be used in the context ofthe present invention. A preferred commercially available SEC resin is the Superdex (Pharmacia) SEC resin, which comprises about 4% agarose matrix with a resin particle size rage of about 45-165 μm. These columns have the ability to resolve proteins having masses of between about 60-2000 kDa.

[00220] The packing and flow rates used in conjunction with the size-exclusion chromatography resin can significantly impact the ability to effectively obtain a size purified viral vector particle composition from the SEC column. For example, tighter packing reduces void volume as well as dilution ofthe virus during purification. A preferred SEC purification method ofthe invention in this respect comprises (a) obtaining an viral vector particle composition comprising a population of viral vector particles and an undesired biomolecule, (b) preparing a packed size-exclusion chromatography column by packing an size-exclusion chromatography resin in a column at a rate of at least about 1.5 times the flow rate used for passing an adenovirus composition through the packed size- exclusion chromatography column, (c) loading the viral vector particle composition onto the packed size-exclusion chromatography column, (d) eluting the viral vector particle composition from the size-exclusion chromatography column, and (e) collecting a portion ofthe eluted composition to obtain a purified viral vector particle composition. [00221] Preferably, the packing rate ofthe size-exclusion chromatography resin is at least about 70 cm/hr per column. More preferably, the packing rate ofthe size-exclusion chromatography resin is about 90-200 cm/hr. Slower flow rates allow the optimal separation ofthe product from impurities. Accordingly, the flow rate used in conjunction with the size-exclusion chromatography resins ofthe invention is generally at least about 20 cm/hr or more. Preferably, the size-exclusion chromatography resin has a flow rate of about 50-100 cm/hr, and, more preferably, about 60-80 cm/hr. Size-exclusion chromatography resins are generally rated according to the ability to separate a globular protein from a desired product.

[00222] The SEC purification method ofthe invention allows a higher volume ofthe viral vector particle composition to be loaded onto the size-exclusion chromatography column, which has many advantages. Previously, only about 3% or less ofthe total size-exclusion chromatography column volume was achievable by techniques known in the art. However, the present inventive method allows the viral vector particle composition to be loaded onto the size-exclusion chromatography resin in an amount of about 4%-15% ofthe total size- exclusion chromatography column volume.

[00223] The alteration of specific buffer components, such as salt concentration, may improve separation ofthe viral vector particle composition during SEC and, thus, size purification of a portion ofthe viral vector particle composition. In this respect, for example, the SEC column is desirably loaded with a solution (e.g., buffer) comprising at least about 400 mM of a monovalent salt (e.g., NaCl). Preferably, the buffer comprises at least about 500-1200 mM, and, more preferably, about 1000 mM, of a monovalent salt (e.g., NaCl). Divalent salts are also contemplated for use in the present invention, hi this respect, it is contemplated to load and/or elute the viral vector particles with a composition comprising at least about 250-600 mM of a divalent salt (e.g., MgCl₂). [00224] In a related aspect, the invention provides a method of preparing a purified viral vector particle composition which comprises (a) obtaining an viral vector particle composition comprising a population of viral vector particles and an undesired biomolecule, (b) loading the viral vector particle composition onto a column comprising (1) a silica-based delipidation membrane, (2) a hydrophobic interaction chromatography resin, (3) an ion exchange chromatography resin, or (4) any combination of (l)-(3), (c) eluting the viral vector particle composition from the column comprising (1), (2), (3) or (4), (d) loading the eluted viral vector particle composition onto a column comprising an anion exchange chromatography resin functionalized with a tertiary amine binding moiety comprising at least three carbon atoms, a quaternary amine binding moiety, or both, wherein the anion exchange chromatography binding moiety is more selective for viral vector particles than a DEAE binding moiety, (e) eluting the viral vector particle composition from the column comprising an anion exchange chromatography resin, (f) loading the eluted composition onto a column comprising a size-exclusion chromatography resin, (g) eluting the viral vector particle composition from the column comprising a size-exclusion chromatography resin, and (h) collecting a portion ofthe eluted viral vector particle composition to obtain a purified viral vector particle composition. Preferably the tertiary amine binding moiety is a dimethylaminopropyl moiety, dimethylaminobutyl moiety, dimethylaminoisobutyl moiety, or dimethylaminopentyl moiety. Optionally, the method can further comprise subjecting the composition in step (d) to an endonuclease. Moreover, the method also can further comprise, after step (h), subjecting the viral vector particle composition to at least one filtration step. The filtration step can be a bulk filtration step and/or a formulation step (e.g., a diafiltration step placing the viral vector particles into a long term storage buffer comprising about 4-6% trehalose).

[00225] It will be understood that the above described three-step chromatography purification process can be narrowed down to a two-step chromatography purification process. Such a two-step process is performed in the same manner but is free of a first column (e.g., capture column). In this respect, the viral vector particle composition in step (a) is loaded directly onto the anion exchange column in step (d). [00226] The present invention also provides a method for preparing an viral vector particle composition involving the use of at least one negative (i.e., non- viral vector binding) chromatography column, typically in addition to or in place of any ofthe above- described capture columns. In such an application, the viral vector particles are loaded in a high salt buffer onto an anion exchange chromatography resin before the salt is diluted. In the high salt buffer, the viral vector particles fail to bind to the column, but non-viral encapsidated polynucleotides (e.g., DNA impurities) are bound by the column. Nucleic acid affinity chromatography columns in this respect are described in, e.g., Chockalingan et al., Methods Mol. Biol, 147:141-53 (2000), Gadgil et al., A Val. Biochem, 290(2):147-78 (2001), Goss et al., J. Chromatogr., 588(l-2):157-64 (1991), Longland et al., Protein Expr. Purif, 6(l):25-32 (1995), Miner et al, Nucleic Acids Res., 24(19):3806-10 (1996), West et al., Bioorg. Med. Cehm. Lett, 11(20): 2227-30 (2001), Taug et al., J. Biochem Biophys Methods, 30(1), 75-8 (1995), and Wada et al., Methods Enzymol, 254:595-604 (1995). After the salt concentration is lowered, which is generally accomplished in a size-exclusion chromatography column buffer exchange, the viral vector particles bind to the column but the salt is left high enough to prevent the binding ofthe protein impurities. Such a negative chromatography method comprises, e.g., (a) obtaining an viral vector particle composition comprising a population of viral vector particles and an undesired biomolecule (typically, an undesired non-viral encapsidated polynucleotide), (b) loading the viral vector particle composition onto a column comprising a negative chromatography resin, (c) collecting the viral vector particle composition which does not bind to the negative chromatography resin, (d) loading the collected viral vector particle composition onto a column comprising an anion exchange chromatography resin functionalized with a tertiary amine binding moiety comprising at least three carbon atoms, a quaternary amine binding moiety, or both, wherein the anion exchange chromatography binding moiety is more selective for viral vector particles than a DEAE binding moiety, (e) eluting the viral vector particle composition from the column comprising an anion exchange chromatography resin, (f) loading the eluted viral vector particle composition onto a column comprising a size-exclusion chromatography resin, (g) eluting the viral vector particle composition from the column comprising the size- exclusion chromatography resin, and (h) collecting a portion ofthe eluted viral vector particle composition to obtain a purified viral vector particle composition. In such a method, the negative chromatography resin is responsible for removing DNA impurities from the viral vector composition as well as for removing protein impurities from the viral vector composition. Exemplary columns for removal of non- viral vector particle component proteins or other undesired biomolecules are provided in Buchachas et al., Biotechnol. Prog, 17(l):140-9 (2001), Kang and Luag, Process Biochem, 36(l-2):85-92 (2000), Vissers et al., J Chromatogr. B. BiomedAppl, 686(2), 119-28 (1996), and Wilsson et al, Prog. Clin. Biol. Res., 150:225-41 (1984).

[00227] hi a negative chromatography process, any suitable chromatography resin can be used. For example, the resins employed in the purification column also can be used in a negative chromatography process (e.g., POROS D), however, different loading conditions are used such that the negative chromatography effect is achieved. For example, the resin can be designed to bind to a known impurity, such as by the incoφoration of antibodies bound to the resin, which are specific for the impurity. Other loading conditions can be altered to specifically bind impurities such as utilizing the salt concentration or the pH. [00228] In the above described chromatography purification process, it will be understood that the columns, whether two or three columns are utilized, can, if desired, be connected in series. Preferably, two columns, which both comprise ion exchange chromatography resins, will be connected in series, and, optionally, the column comprising the size-exclusion chromatography resin will either be connected in series to the second ion exchange column, or will be separate from these columns in which case the eluant from the second ion exchange column will first be collected and then applied to the size-exclusion chromatography column. In view ofthe above, the present invention provides a method for preparing a purified viral vector particle composition utilizing a chromatography process wherein the columns are connected in series. Such a method comprises (a) obtaining viral vector particle composition comprising a population of viral vector particles and an undesired biomolecule, (b) providing a first column comprising an ion exchange chromatography resin and providing at least one additional chromatography column (e.g., any ofthe aforementioned columns), wherein the first and the at least one additional columns are connected in series, (c) loading the viral vector particle composition onto the first column in an amount greater than the capacity ofthe first column such that the first column becomes saturated and creates an overflow ofthe viral vector particle composition, which overflow directly runs into the at least one additional column(s), (d) independently eluting each column, and (e) collecting a portion of each eluted composition to obtain one or more purified viral vector particle composition(s). In one embodiment, the at least one additional column consists of one column comprising an ion exchange chromatography resin connected in series to the first column. The eluted composition from the first anion exchange chromatography column and/or the at least one additional column can then be collected and loaded (separately or together) onto a column comprising a size-exclusion chromatography resin. The resulting composition can then be run through the size- exclusion chromatography column and a portion ofthe composition can be collected to obtain a purified viral vector particle composition. This purified viral vector particle composition optionally can then be further subjected to at least one filtration step, as discussed above. Alternatively, the at least one additional column consists of two columns which both comprise ion exchange chromatography resins and wherein all three ofthe columns are connected in series.

[00229] Any suitable chromatography columns can be used in the series chromatography aspects ofthe invention. Preferably, the columns-in-series comprise an ion exchange chromatography resin, which is functionalized with a tertiary amine binding moiety having at least three carbon atoms, a quaternary amine binding moiety, or both, wherein the ion exchange chromatography binding moiety is more selective for adenovirus than a DEAE binding moiety. Preferably the tertiary amine binding moiety is a dimethylaminopropyl moiety, dimethylaminobutyl moiety, dimethylaminoisobutyl moiety, or dimethylaminopentyl moiety. It will be understood that the reverse flow technique can be used in conjunction with any number of columns and is generally only employed in the first and second purification columns.

[00230] In any ofthe above "bind and elute" chromatography purification processes (e.g., ion exchange chromatography or hydrophobic interaction chromatography), a reverse flow elution technique can be employed when recovering a purified portion (eluate) ofthe viral vector composition from the column of interest. In such a technique, the viral vector composition is loaded and run through the column in a first direction and is eluted from the column in the direction opposite ofthe first direction. In view ofthe above, the present invention provides a method of using such a technique for preparing a purified viral vector particle composition. Such a method comprises (a) obtaining an viral vector particle composition comprising a population of viral vector particles and an undesired biomolecule, (b) loading the viral vector particle composition onto a chromatography column, (c) eluting the viral vector particle composition from the column, (d) loading the viral vector particle composition onto a column in a first direction, (e) eluting the viral vector particle composition from the column in the direction opposite ofthe first direction, and (f) collecting a portion ofthe eluted viral vector particle composition to obtain a purified viral vector particle composition. Preferably, the chromatography column is a high performance liquid chromatography (HPLC) column. HPLC can be characterized by a very rapid separation with extraordinary resolution of peaks. This is achieved by the use of very fine particles and high pressure to maintain an adequate flow rate. Separation typically can be accomplished in a matter of minutes, or at most an hour. Moreover, only a very small volume ofthe sample is needed because the particles are so small and close-packed that the void volume is a very small fraction ofthe bed volume. Also, the concentration ofthe sample need not be very great because the bands are so narrow that there is very little dilution ofthe sample. By utilizing this technique, dilution ofthe viral vector particles is minimized such that the volume is reduced to a level below that which would be obtainable if the elution ofthe adenoviral vector particle composition in step (e) was done in the same direction as the first direction.

[00231] When employing the reverse flow elution technique, the viral vector particle composition can be loaded onto the chromatography column at any suitable rate. Preferably, the viral vector particle composition is loaded onto the column at a rate of about 250-550 cm/hr. The additional column(s) may be removed after an eluate is eluted from the first, saturated column and be used in purification of another viral vector particle composition. Alternatively, an eluate from the second columns can be used as a "low dose" viral vector particle composition. With respect to any ion exchange chromatography step, it is preferred that the viral vector particle composition is eluted from the column(s) by adding a composition comprising about 400-600 mM NaCl to the column in an amount sufficient to elute a majority ofthe viral vector particles from the column(s). By utilizing such a method, the volume ofthe purified viral vector particle composition that is eluted from the column(s) in step (e) is at least about 15% less than the volume of a purified viral vector particle composition eluted from a column when the viral vector particle composition is eluted in the same direction as it is loaded onto the column. Preferably, the volume ofthe purified viral vector particle composition that is eluted from the column(s) in step (e) is at least about 50% less (e.g., about 60% or less) than the volume of a purified viral vector particle composition eluted from a column when the viral vector particle composition is eluted in the same direction as it is loaded onto the column.

[00232] The viral vector particle composition can be eluted from the column using any other suitable elution technique. Typically, a salt or ionic strength gradient is used to elute the viral vector particle composition from the column. In such a process, various buffers, having different concentrations of a salt, typically are blended together before being applied to the column. In a preferred embodiment ofthe invention, the elution process involves a step elution process. In such a process, the buffers are independently applied to the column in sequential order according to their molarity, with the lower concentration salts being utilized first. Thus, the invention provides a method for eluting at least a portion of an viral vector particle composition from a chromatography column comprising; (a) subjecting resin such that a population of viral vector particles binds to the resin, and (b) eluting at least a portion ofthe composition from the column in a step wise fashion by sequentially lower salt concentration than the succeeding buffer immediately following composition comprising a population of viral vector particles. Preferably, this method is carried out with at least two or more buffers, and, more preferably, with at least five buffers which each comprise a monovalent salt having a concentration of about 250 mM-1.5 M. Generally, the first elution buffer subjected to the column comprises a monovalent salt having a concentration of about 300 mM. Furthermore, the final elution buffer subjected to the column comprises a monovalent salt having a concentration of about 1 M.

[00233] In a step elution process, the switching from one buffer to the next is preferably under the control of an automated programmable control system. Such a system is able to monitor the pH, conductivity, or both, of each elution buffer such that a pre-determined pH level, conductivity level, or both is maintained during elution ofthe portion ofthe composition. The automated programmable control system also can control the collection of fractions comprising the viral vector particles that are eluted from the column. [00234] In order to accurately quantify the number of viral particles either in a sample solution of viral vector particles, such as a solution obtained from crude lysate from cells infected with viral vector particles, a sample solution of an adenovirus can be prepared as described previously. The sample solution ofthe adenovirus particles then can be purified by utilizing one ofthe aforementioned chromatography techniques while determining the absorbance ofthe adenoviral vector particle composition eluted from the chromatography resin at a wavelength sensitive for quantification of adenoviral vector particles as described in the above-referenced '441 PCT application. For comparison, the absorbance of a standard solution of adenovirus, i.e., a solution of adenovirus of known concentration, is determined. Through a comparison ofthe absorbance ofthe sample solution and the absorbance ofthe standard solution, the concentration of viral particles, i.e., the number of viral particles in a given volume, in a sample solution is determined. [00235] The standard absorbance can be a single standard absorbance or a series or group of standard absorbance indicative of a range of concentrations of adenoviral vector particles. The sample absorbance and standard absorbance can be presented in similar or different (though preferably similar) formats, measurements, or units as long as a useful comparison can be performed. For example, a suitable standard absorbance can be an absorbance that is determined from a standard solution of adenovirus that has been treated in the same manner as a sample solution of adenoviral vector particles purified in accordance with the present inventive methods.

[00236] Quantification ofthe number of viral particles is accomplished by comparing the sample absorbance to the standard absorbance in any suitable manner. For example, sample absorbance and standard absorbance can be compared by calculating a standard curve ofthe area under the peak corresponding to the virus elution from the chromatography resin on an absorbance versus time chromatograph. The absorbance of different known concentrations of adenovirus can be plotted on a graph, creating a standard curve. Using linear regression analysis, the sample concentration then can be determined.

[00237] Quantification of viral vector particles also can be determined by way of mass spectrometry, as described in, e.g., U.S. Patent 5,965,358, fluorenscence detection (as described in, e.g., U.S. Patent Application 09/678,439), and/or light scattering (as described in, e.g., International (PCT) Patent Application WO 01/38852.

[00238] Viral vector particles purified in a solution or purified from cells infected with adenovirus using anion exchange chromatography resins can be obtained in solutions that can contain high concentrations of an elution agent, e.g., NaCl. The buffer composition can be readily changed by any suitable technique to any desired buffer, e.g., a sterile, isotonic buffer for mammalian injection (e.g., lactated Ringer's solution) containing suitable excipients (stabilizers and cryopreservants) for long term storage ofthe purified adenovirus. Suitable techniques for changing the buffer composition include, but are not limited to, dialysis, diafiltration, and size-exclusion chromatography. Suitable size-exclusion chromatography matrices include Toyopearl HW-40C and Toyopearl HW40F (TosoHaas, Montgomeryville, PA); Uniflow™, Superflow™, and Ultraflow™ (Sterogene, Carlsbad, CA); Shodex™ (Thomson Instruments, Chantilly, VA); and Bio-Sil™ and Bio-Gel™ (Bio- Rad, Hercules, CA). Each of these chromatography resins has a suitably low protein binding potential. These resins and their equivalents can be used in any ofthe aforementioned SEC purification techniques.

[00239] Another technique that can be used in conjunction with the present invention is reverse-phase chromatography. This technique separates molecules based on differences in hydrophobicity imparted by hydrophobic amino acid residues. The stationary phase (the resin) is hydrophobic and non polar. The initial mobile phase (the buffer), which contains the analyte (e.g., the adenoviral vector particle composition), is an aqueous polar solvent, such as water. Elution from reversed-phase columns is typically accomplished with strong non-polar solvents in a linear gradient.

[00240] While the separation of components is based primarily on differences in hydrophobicity, controlling other factors such as elution gradient, concentration ofthe ion- paring agent, and column temperature can enhance selectivity and resolution allowing for high precision analysis. Consequently, reversed-phase chromatography with low wavelength ultra violet (UV) detection can enhance the applicability of reversed-phase chromatography. Collecting the fractionated components and subjecting them to matrix- assisted laser desoφtion ionization time-of-flight mass spectometry (MALDI-TOR MS) provides a method for positive sample identification through precise molecular weight determination and comparison to cuπent protein databases.

[00241] Reversed-phased chromatography in conjunction with MALDI-TOF MS can be used to determine the relative amount of each protein component and how each protein might change over time of a viral vector particle composition, such as an adenoviral vector particle composition. This technique also can be use to identify a sample, to quantitate a given sample, and, in some instances, it can provide relative purity. Accordingly, reversed- phased chromatography and MALDI-TOF MS can be used in the context ofthe invention for many aspects, which are important in adenoviral vector particle production. [00242] Preferably, the viral vector particle production and purification process ofthe present invention involves the use of one or more automated programmable system(s) during the production and/or purification process (examples of which have been discussed elsewhere herein). Automation is important to the viral vector particle production and purification process for several reasons. Automation allows the key parameters ofthe process to be continuously monitored and recorded, it allows key parameters to be set and maintained, and it allows the process of production, recovery, and purification ofthe viral vectors to be maintained as a closed system. Automation also ensures a relative degree of consistency in viral vector particle composition manufacturing. Preferably included in the automation process is the production ofthe product in bioreactors, the initial recovery ofthe product from the production culture using tangential flow filtration (TFF), and the purification ofthe product using chromatography. Additionally, it is preferable that the manufacture of drug substance (i.e., the final formulation ofthe purified viral vector particle composition), including filling and labeling of vials, are under automated monitoring and/or control for at least one parameter.

[00243] Preferably, during the automation process, several key parameters are monitored, and in some cases, a programmed set point is substantially maintained by the automated equipment. Monitored parameters preferably include temperature, pressure, pH, conductivity, pump output (flow rate), motor output (agitation rate), dissolved gas concentration, or any combination thereof (examples of which are set forth in Table 2).

NA = not applicable

[00244] Using automated equipment in these areas is beneficial for commercial pharmaceutical manufacturing. For example, in the present invention the recovery operations in the TFF system can be performed at a controlled temperature. In such a TFF system, all filtration can be maintained at room temperature (about 18-25° C), with the exception ofthe benzon nuclease treatment (wherein the system is desirably raised to and maintained at about 35° C). In some operations, like concentration and diafiltration, the pump introduces a significant amount of heat that could lead to loss of viral product if not regulated. The automated programmable system can monitor the temperature ofthe viral composition and at such steps, cool the viral composition as necessary in order to substantially maintain the programmed set point temperature. During the treatment with benzon nuclease, the system also desirably will monitor the temperature and heat generated by the pump as necessary to maintain the set point. [00245] During the viral vector particle production process, some steps are monitored and not controlled by the automated programmable system. Monitoring without control is also important. In the chromatography operations several buffers are used, each having a specified pH and conductivity. Continuous monitoring ofthe pH and conductivity provides the artisan with data necessary to demonstrate the control ofthe chromatography conditions. Monitoring is also linked to safety. High limit alarms can be set for parameters such as pressure or temperature that signal for and/or automatically shut down the operation before a more dangerous situation develops.

[00246] Use of automated equipment also allows a closed system to be maintained, containing the product and preventing exposure of operators and environment to the product. In the cases of ultrafiltration and chromatography, every buffer needed will be connected to the automated system before commencing operations, as will the vessel supplying the product to the system and the vessel receiving the product after processing. The automated system controls a series of valves so that the buffers are supplied in the desired sequence for the steps of diafiltration or washing and elution. After the product has been automatically moved to the receiving vessel, that connection favorably will be treated with steam that will inactivate any viras left in the flow path before the connection is broken. A system of valves preferably will automatically close the flow path and prevent exposure ofthe product bulk to the steam.

[00247] The controls for the automated programmable system(s) are preferably customized. An example of a prefeπed programmable system for use with the present invention is a supervisory program called Unicorn (Amersham Biosciences), which is designed for use with chromatography techniques. Unicorn monitors the UV absorbance of the material eluted from the column at three wavelengths (215, 260, and 280 nm) and when the Unicorn system detects the product eluting from the column (any column), a series of valves are changed and the product "peak" is diverted to a dedicated collection vessel (e.g. a sterile bag, which desirably is a fitted bag that sealingly engages the inlet and/or outlet of production/purification devices and/or closed system passageways (e.g., the steam block valves, described herein, or sterile SCD connectors). Collection ofthe signal, its analysis, and the change ofthe valves are desirably monitored and controlled by this automated programmable system.

[00248] The viral vector production and/or purification system ofthe present invention is preferably a closed (environmentally isolated) system, hi the present invention, a closed system is a system in which at no time during the viral production process are the cells, viral-infected cells, or viral vector particles exposed to the external environment or non- sterile solutions. The system can comprise any number of closed system portions. Preferably, the production ofthe viral vector particle composition from at least cell harvest through clarification, TFF concentration and diafiltration (including benzon nuclease digestion), ion exchange chromatography, and SEC and elution therefrom is isolated from the environment.

[00249] Accordingly, in a prefeπed embodiment ofthe present invention, the method of producing a viral vector particle composition includes culturing a population of viral vector packaging cells in a medium within a closed bioreactor, infecting the cells with a viral vector particle and propagating the cells such that a population of viral vector particle infected cells is obtained, harvesting the viral vector particle infected cells by transferring at least a portion ofthe medium comprising the viral vector infected cells to a closed harvesting container through a harvest transfer closed passageway, lysing the viral vector particle infected cells in the harvesting container, or transferring the cells by a microfluidizer closed passageway to a closed microfluidizer which lyses the cells, to obtain an viral vector particle composition, transferring the viral vector particle composition to a closed filter system by a filter transfer closed passageway and filtering the viral vector particle composition to obtain a filtered viral vector particle composition, and transferring the viral vector particle composition to a closed chromatography column system by way of a chromatography transfer closed passageway, subjecting the filtered viral vector particle composition to chromatography column, and eluting a purified viral vector particle composition from the chromatography column, wherein at no point during or between harvesting and elution from the chromatography column are the viral vector particles or, viral vector particle infected cells exposed to the environment.

[00250] The harvested cells can be placed in any suitable sterile container. A preferred sterile container ofthe present invention comprises a sterile plastic bag. Available technology utilizes glass or plastic bottles to keep the virus products free from contamination. While these containers serves as a barrier to the external environment, they have multiple disadvantages. The bottles do not functionally represent a closed system because removing the virus products from the bottles cannot avoid exposing the contents to the external environment.

[00251] Various closed systems comprising flexible bags are known in the art for use in handling multiple contents. U.S. Patents 5,496,301, 4,919,823, and 4,976,707 describe various methods of using flexible bags to handle blood-based products. Other bag containers are known in the art for containing cell culture media (e.g., U.S. Patent 4,910,147) or liquid intended for medicinal use (e.g., U.S. Patent 4,240,482). Despite these approaches, no functionally closed system is currently available to prepare, handle, and store virus products. The present invention provides such a method for maintaining sterile conditions while preparing, handling, and storing virus products. [00252] The sterile bags ofthe present invention can be any suitable size. The sterile bags can hold about IL to greater than 1000L (e.g., IL, 2L, 5L, 10L, 20L, 50L, 100L, 200L, 300L, 500L, 1000L). To support sterile bags of larger volumes, the sterile bags can be placed into rigid walled drums. The sterile bags can be made of any suitable material. Preferably, the sterile bags consist of multiple layers (e.g., about 4 to 6 layers) of film with at least one layer being gas-impermeable. The layer of film that is in immediate contact with the product is preferably ultra low density polyethylene (ULDPE). The material ofthe sterile bags depends on the range of temperature for which the sterile bag will be used. For example, sterile bags that are designed for freezing have different films than those designed for use at room temperature.

[00253] In the present invention, addition to and removal from a sterile storage bag is done using tubing and a connector. The tubing is preferably silicone or C-flex tubing. The connectors can be blank tubing ends (no connectors), quick connect (plastic), or sanitary (plastic, silicone, or stainless steel).

[00254] C-Flex tubing refers to a brand of tubing that can be cut and welded back together. This is accomplished using Sterile Connection Device (SCD) see e.g., Meltzer et al., supra and Lydersen et al., supra. This operation is aseptic, so that the sterility ofthe tubing lumen is maintained. The largest C-Flex tubing that can be used in such an apparatus is about 0.5 inch in diameter. As such, sterile connections desirably are made using a thermal deactivating steam block. Steam blocks achieve sterilization ofthe connections between two sterile containers (e.g., apparatus, such as a bioreactor, and a sterile bag) by thermal deactivation of cells, viruses, bacteria, or other adventitious substances within connected tubing ofthe closed system. Additionally, unlike with c-flex tubing and the SCD, there is no limit to the diameter o the tubing or hose that is used when a steam block is used (e.g., a diameter of at least about 1 inch, at least about 2 inches, or greater (e.g., about 2.5 inches) is suitable for such steam block connectors). To sterilize using a steam block, the ends ofthe tubing to be sterilized are attached to containers A and B and connected by a steam block spool piece. Valves are closed so that the product is not exposed to steam while other valves are opened so the steam supply can be introduced into spool piece. Preferably, a temperature of about 121°C or greater is reached during steam sterilization. It is preferred that the specific pressure is maintained at about 15 psi. The tubing to be sterilized is exposed to the steam for about 15-60 minutes. Preferably, the tubing to be sterilized is exposed to the steam for about 30 minutes. [00255] Preferably, a male connector on a first container (or device) is connected (sealingly engaged or "mated")to a female connector on a second container (or device) such that a closed connection is established. The viral composition can thereby be transfeπed without exposure to the external environment or contaminants from the first container to the second container. To do this, the male and female connectors sealingly engage one another in a closed system. The containers which the viral composition is transfeπed to or from can be a bioreactor, a microfluidizer, a microfiltration filter system, a tangential flow filtration system, a chromatography column, a sterile bag, or any other suitable container. [00256] In a prefeπed embodiment, the harvest transfer closed passageway, microfluidizer closed passageway, filter transfer closed passageway, chromatography transfer closed passageway, or combination thereof comprises a sterile C-flex connector, a steam sterilized steam block connector, or combination thereof. Preferably, the harvest transfer closed passageway, microfluidizer closed passageway, filter transfer closed passageway, chromatography transfer closed passageway, or combination thereof comprise a sterilized steam block connector.

[00257] Additionally, during the production process, the viral vector particles or viral vector particle infected cells are preferably placed within a sterile container in a liquid composition comprising about 1-25% trehalose for a period of at least about 3 hours (e.g., a period of at least about 24 hours, such as about 3 days, about 1 week, about 1 month, or longer), between harvesting and lysing the cells, between filtering the viral vector particle composition and subjecting the viral vector particle composition to chromatography, or both, wherein at least about 70% ofthe non-enveloped viral vector particles remain active at the end ofthe period. The viral vector particle composition can be subjected to freezing and thawing in such sterile containers using techniques described herein while retaining such a high concentration of active viral vector particles.

[00258] When the viral vectors are maintained in the liquid composition between filtering the viral vector particle composition and subjecting the viral vector particle composition to chromatography steps, the container preferably consists essentially of a sterile plastic bag comprising a connector fitted to the closed filter, a connector fitted to the chromatography column, or both.

[00259] In order to assure safety, purity, potency, and stability ofthe viral vector composition, the viral vector composition is preferably thoroughly characterized throughout the viral vector production process. Preferably, the identity ofthe viral vector in the composition is ascertained, the purity ofthe viral vector in the composition is determined, the potency ofthe viral vector particles in the composition is analyzed, and the safety ofthe viral vector composition is established.

[00260] The identity ofthe viral vector particle can be confirmed by any method or technique suitable for determining the identity ofthe viral vector in the composition. Suitable methods for authenticating the identity ofthe viral vector in the composition include, for example, applying PCR methods to test for genetic structural integrity or using SDS-PAGE, mass spectrometry, and/or reverse-phase HPLC to characterize the viral vector in the composition and verify the identity and structural soundness ofthe viral vector particle of interest.

[00261] The purity of the viral vector particle can be confirmed by any method or technique suitable for determining the purity ofthe viral vector composition. Suitable methods and techniques include, for example, analysis of host cell DNA and/or host cell protein by Western Blotting, applying a nuclease (e.g., Benzonase™) to the composition to degrade any host cell nucleic acids, analysis of viral vector particle aggregation using laser light scattering principles, analysis of particulates in the composition, observation ofthe appearance ofthe sample, and/or other analytical biochemical methods as appropriate. [00262] The detection of aggregated viral vector particles using laser light scattering allows for the detection of such aggregates in the composition. The presence of viral vector particle aggregates is unfavorable since the clumping ofthe viral vector particles could result in an increased host immune response to the viral vector particles. Furthermore, when viral vector particles are aggregated, it is more likely that more than one viral vector particle will infect any particular cell, which is undesirable. The detection of aggregated particles is optimally performed using laser light scattering methods. [00263] Laser light scattering methods can be performed using any suitable technique appropriate for measuring and quantitating laser light scattering from a solution. Preferably, the laser light scattering is performed by illuminating a sample with a fine beam of highly collimated and monochromatic light produced by a laser. The scattered light is then measured as a function ofthe angle between the detector and the incident beam direction. The measurement may be restricted to a single fixed angle, a low angle (e.g., low angle laser light scattering (LALLS)), a high angle, or any angle in between. Preferably, measurements are made over a range of angles, such as in multi-angle light scattering (MALS). The use of multi-angle laser light scattering is particularly preferred as multi- angle laser light scattering instruments measure molar mass directly regardless ofthe structure. The method thus can comprise assessing the level of vector aggregation, preferably by light scattering detection and comparing the level of aggregation to a standard (e.g., a standard signal obtained by applying light scattering to a standard composition). The determination ofthe relative aggregation can be used to determine if the viral vector particle composition is suitable and/or whether the contents ofthe composition should be modified, e.g., by addition of surfactants which reduce aggregation. [00264] The potency ofthe viral vector particles in the composition can be evaluated by any suitable method or technique for determining the potency ofthe viral vector particles in the composition. Suitable measurements ofthe potency ofthe viral vector particles include, for example, particle count (PU), FFU, PU:FFU ratio, and levels of transgene expression (e.g., quantity, biological activity and/or the amount of total protein). Particle count and FFU techniques (and thus the determination ofthe PU:FFU ratio) are discussed elsewhere herein.

[00265] The levels of transgene expression in the viral vector particle composition can be measured by any suitable method or technique for measuring transgene expression. Examples of some transgene expression assays are described elsewhere herein. Preferably, transgene expression is characterized by measurements ofthe levels of transgene expression and/or measurements of transgene bioactivity. When the transgene is a secreted protein, levels of transgene activity can, for example, be determined by measuring the levels of secreted protein produced by the cells. Preferably, the levels of secreted protein in the supernatant are measured with ELISA using standard techniques. The ELISA desirably is performed at about 12 to about 36 hours, preferably at about 20 to about 28 hours, more preferably about 23 to about 25 hours (e.g., about 24 hours) after infection ofthe cells with a viral vector particle. Alternatively, levels of transgene expression can be measured by Western Blotting using standard techniques. The Western Blot is preferably performed at about 12 to 36 hours, preferably at about 20 to about 28 hours, more preferably about 23 to about 25 hours (e.g., about 24 hours) after infection ofthe cells with a viral vector particle. [00266] Typically and desirably, the level of expression ranges from about 5 fg/cell to about 100 fg/cell or more, typically about 10 fg/cell to about 80 fg/cell, more typically about 10 fg/cell to about 60 fg/cell, even more typically about 10 fg/cell to about 40 fg/cell, most typically about 10 fg/cell to about 25 fg/cell, although the actual amount will depend on the particular transgene of interest, promoter, and vector configuration. The adenoviral vector particles ofthe invention, particularly the E1-, E4-deficient adenoviral vector particles of the invention, are advantageously able to achieve such levels of gene expression consistently.

[00267] Measurements of transgene bioactivity can be performed using any suitable method or technique for measuring bioactivity. Preferably, bioactivity is measured using a bioactivity assay. A bioactivity assay is typically developed based on the characteristics of the protein activity being measured. For example, the bioactivity of a vascular endothelial growth factor (VEGF) can be measured by adding the VEGF protein to a culture of endothelial cells. If the VEGF possesses suitable bioactivity, the endothelial cells will migrate toward the VEGF. Additional VEGF-related assays are described in, e.g., U.S. Patent Application 09/832,355 and references cited therein. Similarly, the bioactivity of a pigment endothelial derived growth factor (PEDF) can be determined, for example, by strategies such as determining whether cells responsive to PEDF migrate towards the growth factor upon administration; measuring apoptosis; determining capillary tube formation in vitro; determining neurite outgrowth; applying microarray technology; measuring receptor-mediated activity (e.g., phosphorylation, reporter gene expression); performing a pathway activation/hybridization test; analyzing promoter activity; or testing for anti-permeability function. The adenoviral vector particle composition ofthe invention desirably exhibits at least 100% ofthe biological activity of an equivalent amount of PEDF or VEGF protein administered to a target cell (e.g., an organ in a host) over a period of about 2 days, 1 week, and/or 1 month.

[00268] The safety of an adenoviral vector particle composition ofthe invention can be determined by any suitable method or technique appropriate for determining the presence of replication-competent adenovirus (RCA) or the contamination ofthe composition with bacteriological, virological, or endotoxin substances. Suitable methods of determining the presence of RCA are described, e.g., in U.S. Patent 5,994,106. In this respect, the invention provides a substantially RCA-free stock, as described further herein as well as in the referenced '106 patent.

[00269] The viral vector particle desirably is subjected to additional testing as needed. Additional testing can be any testing method or technique necessary for assuring the safety, purity, potency, and stability ofthe viral vector composition. For example, additional testing can include testing for pH, conductivity, osmolarity, seal integrity, fill volume verification, or stopper extractables.

[00270] Characterization ofthe viral vector particle composition can occur at any suitable point during the viral vector particle composition production process. Preferably, testing and characterization assays are performed during at least one or more ofthe steps of upstream processing, downstream processing, the finished product, and/or stability tests on the vialed vector (more typically during a hold between such aspects ofthe process step as described above). More preferably, testing and characterization assays are performed during at least two or more ofthe steps, still more preferably during at least three or more of the steps, most preferably during at least four ofthe steps. More than one assay can be performed during each step. The total number of assays performed from the start ofthe process through the stability tests on the vialed vector is preferably about 30 to about 100, more preferably about 40 to about 90, still more preferably about 50 to about 80, and most preferably about 55 to about 70. The type of test performed at any particular step will vary depending on where the step is in production and what parameters are being investigated. For example, suitable tests during the upstream processing include, e.g., testing the particle concentration and/or potency, screening for adventitious viruses, testing for mycoplasm, evaluating the bioburden, and/or testing for the presence of endotoxin. Suitable tests during the downstream processing include, for example, performing potency assays, determination of biological activity, testing for sample purity, testing for sample identity, testing for the presence of replication-competent adenovirus, testing for endotoxin, and/or determining the bioburden. Appropriate tests performed on the finished product include, for example, sample identity tests, sample purity tests, sample potency tests, sterility tests, presence of endotoxin tests, pH tests, osmolarity tests, conductivity tests, seal integrity tests, fill verification tests, and/or stopper extractable tests. Suitable tests on the stability ofthe final product include any suitable test for determining stability ofthe product, e.g., any ofthe above-mentioned tests for the finished product as appropriate.

[00271] Using the techniques described herein, the present invention provides viral vector particle compositions of significant purity with respect to the impurities such as non- viral encapsidated polynucleotides (e.g., host cell DNA) and non-viral vector component proteins (e.g., host cell proteins), while retaining a high concentration of intact, and, most preferably, active, viral vector particles. For example, in one aspect the invention provides a purified viral vector particle composition (e.g., an adenoviral vector particle composition) that comprises at least about 1 x 10⁴ viral vector particles, at least about 1 x 10⁵ particles, at least about 1 x 10 or more particles, at least about 1 x 10 , or more particles, e.g., at least about 1 x 10⁸ particles, at least about 1 x 10⁹ or more particles, or even at least about 1 x 10¹⁰ particles. Thus, for example, the purified viral vector particle product can comprise, e.g., about 1 x 10¹¹ particles, about 1 x 10¹² particles, about 1 x 10¹³ particles, about 1 x 10¹⁴ particles, about 1 x 10¹⁵ particles or more.

[00272] The adenoviral vector particles in the purified composition are preferably replication-deficient adenoviral vector particles, and the composition desirably has a replication competent adenovirus (RCA) particle/total adenoviral vector particle ratio of less than about 1/1 x 10⁵. More preferably, the composition has an RCA particle/total adenoviral vector particle ratio of less than about 1/1 x 10⁷. Even more preferably, the composition has an RCA particle/total adenoviral vector particle ratio of less than about 1/1 x 10⁹. Most preferably, the composition has an RCA particle/total adenoviral vector particle ratio of less than about 1/1 x 10¹¹. Ideally, the composition has an RCA particle/total adenoviral vector particle ratio of less than about 1/1 x 10 . The presence of RCA can be detected by any suitable method, for example, the method described in U.S. Patent 5,994,106.

[00273] The replication-deficient adenoviral vector particles are furthermore preferably El -deficient adenoviral vector particles. Using the complementing cell lines and techniques described herein, genetic reversions in the deficient adenoviral vectors can be avoided. In this respect, the composition ofthe present invention preferably has an El-revertant adenoviral vector particle to total adenoviral vector particle ratio of less than about 1/1 x 10⁴. More preferably, the composition has an El-revertant adenoviral vector particle to total adenoviral vector particle ratio of less than about 1/1 x 10⁵, and more preferably less than about 1/1 x 10⁶' Ideally, the composition has an El-revertant adenoviral vector particle to total adenoviral vector particle ratio of less than about 1/1 x 10⁷. Optimally, the composition has an El-revertant adenoviral vector particle to total adenoviral vector particle ratio of less than about 1/1 x 10⁸.

[00274] The presence of El-revertant adenoviral vectors in a composition can be detected by any suitable technique known in the art for determining the presence ofthe nucleotide sequence(s) corresponding to the gene functions of interest in the adenoviral vectors ofthe composition. Suitable techniques include, for example, polymerase chain reaction (PCR), southern blotting, or a biological function assay. Preferably, the presence of El-revertant adenoviral vectors in a composition is detected by a biological function assay, such as the method of detecting an El-revertant adenoviral vector provided by the invention. A biological function assay is a method of detecting an El-revertant adenoviral vector by inoculating a cell line that complements for every deficient gene function in the adenoviral vector except for the gene fimction(s) ofthe El region of interest. Thus, only adenoviral vectors that comprise the El region of interest (El-revertants) will propagate in the cell line since the cell line does not complement for the El region of interest and any adenoviral vectors that are deficient in a gene function ofthe El region will not propagate. Cell culture and inoculation can be done using standard molecular biology techniques known in the art. (See, e.g., Maniatis et al., MOLECULAR CLONING: A LABORATORY MANUAL: 2^ND ED., (Cold Spring Harbor Press 1992), Watson et al, RECOMBINANT DNA: 2^ND ED.), (Scientific American Books 1992), Ausubel et al., CURRENT PROTOCOLS IN MOLECULAR BIOLOGY (1987)).

[00275] The presence of El-revertant adenoviral vectors in a composition also can be detected using PCR. Primers can easily be developed specific for the El gene functions deficient in the adenoviral vector ofthe composition. The composition can be purified, or the composition can be treated with a protease (e.g., Proteinase K) and heat denatured. PCR techniques known in the art can be utilized to determine if the El sequence of interest is present in the composition. As a control, PCR can be performed on the sample using primers specific for a cellular gene, such as 18s ribosomal RNA, to determine the presence of host cell DNA contamination in the samples.

[00276] As discussed above, the adenoviral vector particle composition desirably has a low PU/FFU ratio. The production and purification techniques are capable of preparing such composition with remarkably low PU/FFU ratios. For example, adenoviral vector particle composition ofthe present invention can typically have a particle unit/focus forming unit (PU/FFU) ratio of about 50 or less. Preferably, the composition has a PU/FFU ratio about 40 or less. More preferably, the PU/FFU ratio is about 30 or less, and even more preferably, the PU/FFU ratio is about 20 or less. Ideally, the PU/FFU ratio is 10 or less, and optimally, the PU/FFU ratio is 5 or less. A description of PU/FFU and methods to determine the ratio are set forth above. [00277] Additionally, the adenoviral vector particle composition comprises at least about 75% active viral vector particles. More preferably at least about 80% ofthe viral particles are active and even more preferably at least about 85% ofthe viral vector particles are active. Most preferably, about 90% ofthe viral vector particles are active. Ideally, at least about 95% ofthe viral vector particles are active. Optimally, about 100% ofthe viral vectors are active. Suitable methods for assessing viral activity are discussed above. [00278] The adenoviral vectors ofthe invention also exhibit superior levels of gene expression due to their genetic configuration and production using the techniques ofthe invention. Thus, for example, whereupon infection of culture comprising a population of cells with the composition at an MOI of at least about 1 (e.g. at least about 2, 3, 4, 5, 10, 15, 20, 30, 40) and after a suitable period of time for transgene expression to occur, a transgene product in the culture in a concentration of at least about 20 fg/cell will be obtained. More preferably, the level of transgene product in the culture is at least about 30 fg/cell. Even more preferably, the level of transgene product in the culture is at least about 40 fg/cell. Most preferably, the level of transgene product is at least about 50 fg/cell. Ideally, the level of transgene product is at least about 60 fg/cell. Optimally, the level of transgene product is at least about 75 fg/cell (e.g., about 100 fg/cell, about 125 fg/cell). [00279] The methods ofthe invention also offer compositions substantially free of non- viral vector proteins. In this respect, the adenoviral particle composition preferably comprises about 50 ng or less host cell protein per at least about 1 x 10⁵ (e.g., at least about 1 x 10⁶, 1 x 10⁷, 1 x 10⁸, 1 x 10⁹, 1 x 10¹⁰, 1 x 10¹¹, 1 x 10¹², 1 x 10¹³, 1 x 10¹⁴) adenoviral vector particles. More preferably, the composition comprises about 40 ng or less host cell protein per such particle levels. Even more preferably, the composition comprises about 30 ng or less host cell protein per such particle levels. Most preferably, the composition comprises about 20 ng or less host cell protein per such particle levels. Ideally, the composition comprises about 10 ng or less host cell protein per such particle levels. [00280] In a preferred embodiment ofthe present invention, the host cell protein makes up about 5% or less ofthe total protein content ofthe composition. Preferably, the host cell protein makes up less than about 4% ofthe total protein ofthe composition. More preferably, the host cell protein makes up less than 3%, and even more preferably, less than 2%. Most preferably, the host cell protein makes up less than about 1% ofthe total protein ofthe composition. Ideally, the host cell protein makes up 0.5% or less ofthe total protein content ofthe composition. Optimally, the host cell protein makes up 0.25% or less ofthe total protein content ofthe composition.

[00281] Another advantage ofthe methods ofthe invention is in the reduction in the number of empty viral vector particles (viral vector particles that are incomplete, damaged, or lacking genetic material) or "empty capsids." Typically and preferably, less than about 30% ofthe viral vector particles (e.g., adenoviral vector particles) in the composition are empty capsids. More preferably, less than about 20% ofthe adenoviral vector particles in the composition are empty capsids. Most preferably, less than about 10%o ofthe adenoviral vector particles in the composition are empty capsids. Ideally, less than about 5% ofthe adenoviral vector particles in the composition are empty capsids. Optimally, practically 0% ofthe adenoviral vector particles in the composition are empty capsids (e.g., no empty capsids are detectable).

[00282] The presence of empty capsids from adenovirus (virus particles lacking mature adenoviral DNA) in the final purified composition have been well documented in literature (e.g. Vellekamp et al., Hum. Gene Ther. 12, 1923-1936 (2001)). The empty capsids contain three major proteins: hexon, IIA, and a precursor protein to VIII, called pVIII. There is no pVIII in complete virus particles. Therefore, assaying for pVIII precursor protein by SDS- PAGE, RP-HPLC, light scattering techniques, or any other suitable technique can be used to quantify the contamination by empty capsids, and observe the reduction of empty capsid levels by purification conditions. Methods to purify the adenoviral vector particles from the empty capsids include density gradient centrifugation (e.g., cesium chloride centrifugation) and column purification (e.g. Vellekamp et al. supra). In most aspects ofthe invention, however, the composition typically and desirably is prepared without density gradient centrifugation. The composition also desirably can be prepared without application of electrophoresis.

[00283] In a preferred embodiment ofthe present invention, an adenoviral vector composition comprises at least about 1 x 10⁵ adenoviral vector particles and about 30 ng or less of non- viral encapsidated DNA of about 120 base pairs (bp) or more in length per at least about 1 x 10⁵ adenoviral viral particles. Preferably, the adenoviral vector composition comprises at least about 1 x 10⁵ (e.g. at least about 1 x 10⁶, 1 x 10⁷, 1 x 10⁸, 1 x 10⁹, 1 x 10¹⁰ i i i <y ι

,1 x 10 , 1 x 10 , 1 x 10 ) particles and about 30 ng or less (e.g., about 20 ng or less, about lOng or less, about 5 ng or less, about lng or less) of non- viral encapsidated DNA of at least about 120 bp or more in length (e.g., at least about 400 bp or more in length, at least about 750 bp or more in length) per at least about 1 x 10⁵ adenoviral viral particles. The amount of non- viral encapsidated DNA of about 120 bp, about 400 bp, and/ or about 750 bp in length in the purified composition sample and/or crude cell lysate sample is preferably determined by quantitative real-time PCR (e.g., TaqMan®, Perkin Elmer/ Applied BioSciences).

[00284] In order to further assess the purity ofthe adenoviral vector particle composition, the present invention provides a novel host cell protein assay. This assay measures the purity ofthe viral vector particle composition by the determining the amount of host cell protein in the viral vector composition. Specifically, this assay assesses the approximate amount of protein fragment having an apparent molecular weight of about 70 kDa (as determined by Western Blot) in the purified viral vector particle composition as a marker of purity ofthe product.

[00285] The novel host cell protein assay utilizes a Western Blot assay to recognize multiple cellular proteins. To do this, antibodies were raised against the prefeπed cells for use with the viral vector production method (e.g., 293-ORF6 cells). Though, commercial kits are available which contain polyclonal antibodies against 293 cells, these antibodies were nonspecific for 293-ORF6 host cell protein, such that a suitable Western Blot could not be obtained against 293-ORF6 cell lysates. The inventors have prepared similar assays against El -complementing HER cells.

[00286] To produce the polyclonal antibodies against the HER and 293-ORF6 cells, goats were immunized repeatedly with host cell protein from either HER or 293-ORF6 cells to generate a high titer of appropriate antibodies. To avoid the viral protein background in test animals that may have been previously exposed to the virus, the antibodies were affinity purified. The strongest band present in every purified product tested (based on chromatography, rather than density gradient centrifugation purification) is a cellular protein fragment having an apparent molecular weight of about 70kDa. Because the intensity of this band varies with application of additional purification steps, the amount of "the 70kDa fragment" can serve as a marker of relative purity for the purified product. [00287] In order to determine the approximate amount ofthe 70kDa protein fragment, serial dilutions of a known amount of cellular protein are run on an SDS-Page gel and a Western Blot is performed using labeled polyclonal antibody probes which hybridize with host cell proteins (e.g., such techniques have been successfully performed with the aforementioned HER and 293-ORF6 cells). Using a computer software program (hnageMaster ID Elite), the amount of protein in the 70kDa fragment can be semi- quantitated at several dilutions of known amounts of cellular protein. The software system creates a plot with a standardized curve to semi-quantitatively estimate the 70kDa protein amount in any sample. For example, when the total host cell protein in a 293-ORF6-derived composition is about 40 ng, the 70kDa fragment was determined to account for about 6ng of the total host cell protein. Additionally or alternatively, visual comparison between Western Blots can be used to determine the approximate amount of host cell protein, and in particular, the 70kDa fragment.

[00288] In a preferred embodiment, the adenoviral vector composition comprises at least about 1 x 10⁵ (e.g., at least about 1 x 10⁶, 1 x 10⁷, 1 x 10^s, 1 x 10⁹, 1 x 10¹⁰, 1 x 10¹¹, 1 x 10¹², 1 x 10¹³) adenoviral vector particles and the composition further comprises less than about 30 ng of protein fragments having an apparent molecular weight of about 70kDa. More preferably, the composition comprises less than about 20 ng of protein fragments having an apparent molecular weight of about 70kDa. Even more preferably, the composition comprises less than about 15 ng of protein fragments having an apparent molecular weight of about 70kDa. Ideally, the composition comprises less than about 10 ng of protein fragments having an apparent molecular weight of about 70kDa, and even more ideally, less than about 5 ng of protein fragments having an apparent molecular weight of about 70kDa.

[00289] In another prefeπed embodiment, the invention provides a method for obtaining a purified stock of adenoviral vector particles comprising, subjecting an adenoviral vector particle composition to benzon nuclease digestion at about 34-36° C for at least about 4 hours to obtain a reduced DNA level composition, subjecting the reduced DNA level composition to tangential flow filtration to obtain a filtered composition, subjecting the filtered composition to ion exchange chromatography purification using an ion exchange chromatography resin comprising a binding moiety more selective for adenovirus particles than DEAE to obtain an IEC purified composition, and subjecting the purified composition to size-exclusion chromatography to obtain a purified adenoviral vector particle composition, wherein the method is performed without cesium chloride centrifugation and the purified adenoviral vector particle composition has a PU/FFU ratio of less than about 30 and less than about 30 ng (e.g., 20 ng, 10 ng, 5 ng) of non-viral encapsidated DNA of about 750 base pairs or more in length per at least about 1 x 10⁵ adenoviral vector particles. Preferably, this method also results in a purified adenoviral vector composition with about 30 ng or less (e.g., 20 ng, 10 ng, 5 ng) of non-viral encapsidated DNA of about 410 base pairs or more in length. Moreover, the method results in less than about 30 ng (e.g., 20 ng, 10 ng, 5 ng) of non- viral encapsidated DNA of about 120 base pairs or more in length. [00290] The present invention also provides a method of assessing the effectiveness of a purification technique used to prepare an adenoviral vector composition comprising subjecting the composition before and after the purification technique is applied to Western Blot analysis and evaluating whether the amount of protein having an apparent molecular weight of about 70kDa protein is reduced after performing the technique. This can be done by comparison with a known standard or visual inspection ofthe blot. Additionally, the purity ofthe adenoviral vector composition can be assessed by visually or semi- quantitatively (with use of a standard) to assess the protein amount of protein in the 70kDa fragment. The comparison ofthe amount of 70kDa fragment protein can be used to assess the purity ofthe adenoviral protein following a purification technique, wherein the purification technique is repeated if the amount of protein having an apparent molecular weight of about 70kDa in the adenoviral vector particle composition is not reduced after performing the technique. [00291] Additionally, the present invention provides for a method of preparing a polyclonal antibody composition that visually reacts with host cell proteins in an adenoviral vector particle composition in a Western Blot assay comprising providing adenoviral vector infected host cells, lysing the cells to obtain a lysate, preparing a composition comprising polyclonal antibodies to a majority ofthe proteins the lysate at a titer such that at least a majority ofthe host cell proteins can be visualized on a Western Blot, subjecting the polyclonal antibodies to affinity column chromatography purification using at least a majority ofthe adenoviral vector particle's proteins to obtain a purified host cell protein polyclonal antibody composition to obtain a polyclonal antibody composition that visually reacts with host cell proteins in an adenoviral vector particle composition in a Western Blot assay. The host cell protein contamination in an adenoviral vector particle composition can be assessed by subjecting the adenoviral vector particle composition to Western Blot analysis using these polyclonal antibodies.

[00292] When a purified adenoviral vector particle composition is compared with the lysate of adenoviral vector particle host cells (from which the purified adenoviral vector particle composition was derived), the purified composition exhibits a reduction of host cell DNA by a factor of at least about 3 logs as compared to the amount of host cell DNA in the unpurified lysate. More preferably, the host cell DNA is reduced by at least about 4 logs. Most preferably, the host cell DNA is reduced by at least about 5 logs. Ideally, the host cell DNA is reduced by at least about 6 logs. Similarly, it is preferably that the purified composition exhibits a reduction of host cell protein by a factor of at least about 3 logs as compared to the amount of host cell protein in the unpurified lysate. More preferably, the host cell protein is reduced by at least about 4 logs. Most preferably, the host cell protein is reduced by at least about 5 logs. Ideally, the host cell protein is reduced by at least about 6 logs.

[00293] In another prefeπed embodiment, a method of assessing the effectiveness of a purification technique used to prepare an adenoviral vector composition comprising subjecting the composition to enzyme immunoassay (EIA) analysis both before and after the purification technique is applied and evaluating whether the amount of protein having an apparent molecular weight of about 70kDa protein is reduced after performing the technique. Enzyme immunoassays are known in the art and include the standard enzyme linked immunosorbant assays (ELISAs), which is discussed above (e.g., Schachter, Immunol. Invest. 26(1-2), 157-61 (1997), Gniewek et al, Clin Diagn Lab Immunol 4(2), 185-8 (1997), Porstmann et al., J Immunol Methods 150(1-2), 5-21 (1992)). [00294] The present invention includes a method of assessing the purity of an adenoviral vector composition comprising subjecting the adenoviral vector composition to EIA analysis (e.g., by ELISA) and evaluating the amount of protein having an apparent molecular weight of about 70kDa. If the after the EIA is performed, the amount ofthe protein having an apparent molecular weight of about 70kDa in the adenoviral vector particle composition is not reduced, it is preferably that the purification is repeated until an acceptable level of purity is reached.

[00295] Additionally, the invention provides a method of preparing a polyclonal antibody composition that visually reacts with host cell proteins in an adenoviral vector particle composition in an enzyme immunoassay (EIA) comprising providing adenoviral vector infected host cells, lysing the cells to obtain a lysate, preparing a composition comprising polyclonal antibodies to a majority ofthe proteins ofthe lysate at a titer such that at least a majority ofthe host cell's proteins can be visualized by EIA, subjecting the polyclonal antibodies to affinity column chromatography purification using at least a majority ofthe adenoviral vector particle's proteins to obtain a purified host cell protein polyclonal antibody composition to obtain a polyclonal antibody composition that visually reacts with host cell proteins in an adenoviral vector particle composition in a EIA (e.g., ELISA).

EXAMPLES [00296] The following examples further illustrate the invention but, of course, should not be construed as in any way limiting its scope.

EXAMPLE 1 [00297] This example describes the production of a population of E4-deleted, replication- deficient adenoviral vector particles in 293-ORF6 E4-complementing human embryonic kidney (HEK) cells.

[00298] A culture of 293-ORF6 cells at a density of approximately 1.5 x 10⁵ to 2 x 10⁵ cells/mL was incubated in shaker flasks. When the 293-ORF6 cells reached a density of about 1 x 10⁶ cells/mL, fresh medium was added to bring the cell density back to a concentration of about 1.5xl0⁵to about 2xl0⁵ cells/mL. The cells were split into additional shaker flasks as needed to keep the volume of medium in each flask constant. The cells were incubated in this fashion until about 4xl0⁸ to 5xl0⁸ total cells were obtained, at which point the cells were adjusted to a concentration of approximately 4xl0⁵ to 5xl0⁵ cells/mL in 1 L with fresh medium. The cells were transferred into a 5 L bag using a sterile cell- transferring tubing set and a peristaltic pump or a steam block in a Bio-Safety Cabinet, forming an environmentally isolated (i.e., closed) transfer system between the shaker flask, tubing, and bag.

[00299] The 5L bag containing the 1 liter of cell culture was connected to a 2L bioreactor through the sterile tubing by a Sterile Connecting Device (SCD), forming an environmentally isolated (i.e., closed) transfer system between the bioreactor, tubing, and bag. The cells were then transfeπed from the 5 L bag into the 2 L bioreactor by a peristaltic pump for further culturing. As the cell density ofthe 1 liter cell culture in the bioreactor reached approximately 1 x 10⁶ cells/mLs, an additional liter of fresh medium was fed into the bioreactor to bring the total culture to a total volume of 2 liters at a cell density of about 4xl0⁵ to 5x10⁵ cells/mL. Once the 2 liter cell culture reached a cell density of approximately 1 x 10⁶ cells/mL, an additional 3 L of medium was added to the cell culture and the 5 L culture was transfeπed to a 10 L production bioreactor using sterile SCD tubing, a peristaltic pump, and a SCD or a steam block, where the 5 L cells cell culture was further fed to 10 L in a fed batch mode when cell density ofthe 5L culture reached approximately 1 x 10⁶ cells/mL.

[00300] Once the cell density ofthe 10 L culture reached above 1 x 10 cells/mL, the cells were infected with adenoviral vector particles. No medium exchange was performed prior to infection, and the cells were infected in about 100% spent media. At about 8 to 24 hours post infection (hpi), a medium exchange with about 5L of fresh medium was performed. The cells were harvested from the bioreactor at about 48 hpi into sterile plastic bags using sterile tubing, a peristaltic pump, and a SCD or a steam block, where the cells were held at - 80°C pending the commencement of further purification. Alternatively, the cells were then directly subjected to microfluidization lysis as described herein to obtain an adenoviral vector particle composition.

[00301] This example demonstrates that 293-ORF6 cells can be cultured to high cell densities in a closed system suitable for production of an adenoviral vector particle composition.

EXAMPLE 2 [00302] This example describes the production of a population of replication-deficient adenoviral vector particles in human embryonic retinal (HER) cells. [00303] A culture of HER cells at a density of approximately 2.5xl0⁵ to 3xl0⁵ cells/mL was incubated in shaker flasks. When the HER cells reached a density of about 1 x 10⁶ cells/mL, fresh medium was added to bring the cell density back to about 2.5xl0⁵ to 3xl0⁵cells/mL. The cells were split into roller bottles as needed to keep the volume of medium in each roller bottle constant. The cells were incubated in this fashion until about 8x10 to 1 x 10 total cells were obtained, at which point the cells were adjusted to a concentration of approximately 4xl0⁵ to 5xl0⁵ cells/mL in 2 L with fresh medium. The cells were transferred into a 5 L bag using a sterile cell-transferring tubing set and a peristaltic pump in a Bio-Safety Cabinet.

[00304] The 5 L bag containing the 2 L of cell culture was connected to a 3.5 L bioreactor through the sterile tubing by a Sterile Connecting Device (SCD), forming an environmentally isolated (i.e., closed) transfer system between the bioreactor, tubing, and bag. The cells were then transfeπed from the 5 L bag into the 3.5 L bioreactor by a peristaltic pump for further culturing. As the cell density ofthe 2 L cell culture in the bioreactor reached approximately 1 x 10⁶ cells/mL, 1.5 liter of fresh medium was fed to bring the total culture volume to about 3.5 L at a cell density of about 6xl0⁵ cells/mL. Once the 3.5 L cell culture reached approximately 1 x 10⁶ cells/mL, 1.5 L of fresh medium was added to the cell culture and the cell culture was transferred to a 10 L production bioreactor using sterile tubing, a peristaltic pump, a SCD, or a steam block. The 5 L cell culture was further fed to 10 L in a fed batch mode in the production bioreactor when cell density ofthe 5 L culture reached approximately 1 x 10 cells/mL.

[00305] Once the density ofthe 10 L cell culture reached above 1 x 10⁶ cells/mL, the cells were infected with adenoviral vector particles (see, e.g., U.S. Patent 6.168,941). Before infection of HER cells, a quick (intense) medium exchange was performed. During the quick medium exchange, approximately 90% to 99% ofthe media was exchanged for fresh media. The cells were infected with adenoviral vector particles, harvested about 48 hours after infection, and fransfeπed into sterile plastic bags using sterile tubing, a peristaltic pump, and a SCD or a steam block, where the cells were held at -80°C pending the commencement of further purification methods. The cells were then directly subjected to microfluidization lysis as described herein to obtain an adenoviral vector particle composition.

[00306] This example demonstrates that HER cells can be cultured to high cell densities in a closed system suitable for production of an adenoviral vector particle composition.

EXAMPLE 3 [00307] This example demonstrates the direct adaptation of adherent E4-complementing adenoviral packaging cells to a serum-free suspension culture.

[00308] One T- 175cm² flask of 293-ORF6 adherent cells in serum-containing medium at approximately 90% confluency was obtained. The serum-containing medium was aspirated off and the cells were washed once with phosphate buffered saline (PBS). 25 mL of SFMII (GIBCO) medium, 0.5 Dg/mL of puromycin, and 4mM of glutamine was added into the same 175cm² T flask. The T flask was placed in an incubator at 37°C, 5% CO₂ with no agitation for 48 hours.

[00309] After 48 hours, the cells were detached from the T flask and pipetted into a 50 mL conical tube and centrifuged at 1000 rpm for 5 minutes. The spent medium was removed and discarded. The cells were suspended in 10 mL of fresh SFMII with 0.5 Dg/mL of puromycin and 4 mM of added glutamine. Five mL ofthe resuspended cells were pipetted into each of two 125 mL vented cap Erlenmeyer shaker flasks. 20 mL of SFMII serum-free medium plus 0.5 Dg/mL of puromycin (as the selection reagent for ORF6 gene expression) and 4 mM of glutamine was added to each shaker flask. The cells in suspension were cultured by shaking at 120 φm, 37°C, 5% CO₂ for 48 hours. [00310] The cells in the serum-free suspension were tested for adenoviral vector particle production and compared to adenoviral vector particle production in cells grown in serum- containing medium. Cells in suspension in serum-free medium (SF/Susp), cells in suspension in serum-containing medium (S/Susp), and adherent cells in serum-containing medium (Adh) were infected with either an AdGvVEGF.10 (an El -deleted adenoviral vector carrying a VEGF transgene), AdovVEGF.l 1 (an El, E4-deleted vector carrying a VEGF transgene), or AdGvTNF.l 1 (an El, E4-deleted vector carrying a TNF transgene) at the same MOI of about 20 FFU/cell.

[00311] Adenoviral vector particle production was measured in FFU/cell using standard techniques. Results ofthe experiment in average FFU/cell for each adenoviral vector particle in each type of cell are shown in Table 3.

TABLE 3

[00312] The results ofthe experiments reflected in Table 3 demonstrate that serum-free medium-adapted HEK cells in serum-free suspension produce significantly increased amounts of adenoviral vectors as compared to cells in serum suspension or adherent cells in serum-containing medium. Moreover, these results demonstrate that adherent cells from serum-containing medium cultured cell lines can be suitably adapted to serum-free medium for efficiently producing adenoviral vector particle compositions.

EXAMPLE 4 [00313] This example demonstrates that culturing cells in the presence of effective amounts of IGF and EGF results in an increase in adenoviral vector particle production. [00314] Cell cultures of 293-ORF6 cells having an estimated density of 2 x 10⁵ cells/mL in 30-40 mL of a test medium were seeded in 125 mL shaker flasks. The media tested were (1) SFMII (GIBCO), a serum-free and animal protein-free medium, without IGF and EGF, and (2) SFMII with 10 ng/mL IGF and 10 ng/mL EGF added. The cells were cultured by shaking at 120 ipm at 37°C, 5% CO₂. When cells reached a density of about 4 x 10⁵ cells/mL, they were infected with recombinant El-deficient, E4-deficient adenoviral vector particles comprising a human TNF-α gene sequence in place ofthe deleted El -region and a transcriptionally inert β-glucoronidase gene (spacer) in place ofthe deleted E4-region (AdovTNF.l 1) in about 50% spent media at a MOI of about 20 FFU/cell. The cells were incubated at 37°C in 5% CO₂. At 48 hpi, the cells were harvested and analyzed for AdovTNF.l 1 particle production by standard HPLC-PU assay and FFU assay techniques. [00315] The results ofthe experiment are shown in Table 4.

TABLE 4

[00316] The results ofthe experiments, as reflected in Table 4, demonstrate a significant increase in AdovTNF.l 1 production in cells grown in SFMII with the addition of IGF and EGF. Specifically, an increase in AdovTNF.l 1 production in 293-ORF6 cells grown in SFMII medium of approximately 0.7 x 10¹⁰ PU/mL was observed after 31 passages, and an increase in AdovTNF.l 1 production in 293-ORF6 cells grown in SFMII with the addition of IGF and EGF of approximately 1.72 x 10¹⁰PU/mL was observed after 39 passages. As such, these results demonstrate that culturing packaging cells in the presence of an effective amount of IGF and EGF can significantly increase adenoviral vector production.

EXAMPLE 5 [00317] This example demonstrates the cell density-independent increase in adenoviral vector particle production in the presence of a growth factor cocktail comprising IGF and EGF.

[00318] Adenoviral vector particle production in an E 1 -complementing human embryonic retinal (HER) cell was determined. Cell cultures having an estimated density of 2 x 10⁵ cells/mL in 30-40 mL of a test medium were seeded in 125 mL shaker flasks. The media tested were ExCell 525 medium (JRH), CD293 medium (GIBCO), SFMII medium (GIBCO), GTRB medium (SIGMA), and Pro293s medium (BioWhittaker). A second set of cell cultures was prepared and modified by the addition of IGF and EGF to the referenced media until a concentration of 10 ng/mL IGF and 10 ng/mL EGF was obtained. All ofthe HER cells were cultured by shaking at 100 φm at 37°C, 10% CO₂. The HER cells were infected at about 7 x 10⁵ cells/mL with recombinant El -deficient adenoviral particles 100

comprising a transgene encoding human VEGF₁₂₁ inserted into the deleted portion ofthe El region ofthe adenovirus genome (AdovVEGF.lO) at a MOI of about 20 FFU/cell and incubated at 37°C, 10%) CO₂. At 48 hours post infection, the cells were harvested and analyzed for AdovVEGF.lO particle production by standard HPLC-PU assay and FFU assay techniques.

[00319] The average increase of AdovVEGF.10 particle production by cells grown in media with the addition of EGF and IGF to the cell medium as compared to AdovVEGF.lO particle production by cells grown in media without the addition of EGF and IGF was 95% in PU/cell as determined by the HPLC-PU assay and 103% in FFU/cell as determined by the FFU assay.

[00320] The results of this experiment evidence that the addition of significant levels of EGF and IGF during culture of adenovirus packaging cells results in a cell-density independent increase in the yield of adenoviral vector particles in various cell media.

EXAMPLE 6 [00321] This example demonstrates the stability of 293-ORF6 cells in serum-free suspension during infection with AdovTNF.11 viral vector particles as determined by average doubling time.

[00322] Cell cultures of 293-ORF6 cells having an estimated density of 2 x 10⁵ cells/ml in 30-40 ml of a test medium were seeded in 125 ml shaker flasks. The cells were grown in SFMII medium with 10 ng/ml IGF and 10 ng/ml EGF added. The cells were cultured by shaking at 120 φm at 37°C, 5% CO₂. Cells were infected with recombinant El-deficient, E4-deficient adenoviral vector particles comprising a human TNF-α gene sequence in place ofthe deleted El -region and a transcriptionally inert β-glucoronidase gene (spacer) in place ofthe deleted E4-region (Ad_G TNF.l 1) and incubated at 37°C in 5% CO₂. [00323] The average doubling time ofthe cells was recorded beginning at the time of infection (T= 0). The results are shown in Table 5.

[00324] The results ofthe experiment, as reflected in Table 5, demonstrate a stable average doubling time in hours of 293-ORF6 cells in serum-free suspension infected with AdovTNF.11 viral vector particles over a course of about 65 accumulated doublings. The consistency ofthe growth profile ofthe 293-ORF6 cells infected with AdovTNF.l 1 viral vector particles in this experiment reflects the stability of 293-ORF6 cells in serum-free suspension during and after infection.

EXAMPLE 7 [00325] This example demonstrates the increased adenovirus vector production in 293- ORF6 cells when the cells were infected with adenoviral vector particles in at least about 50% spent medium. The example further demonstrates the additional increase in adenoviral vector production in 293-ORF6 cells when the cells were infected in at least about 50% spent medium followed by an about 50% fresh medium exchange performed at about 8-10 hours post infection.

[00326] The 293-ORF6 cells were cultured in 2 L Applikon Bioreactors (Applikon, Inc.) in fed-batch mode. When the cell densities in the bioreactors reached about 1.5 x 10⁶ cells/mL, the cells were taken from the bioreactors for infection. About 20 mL of cell culture in 125 mL shaker flasks were infected under conditions such that 0%, 25%, 50%, 75%, or 100% ofthe cell medium was spent at infection (three independent infections were performed for each ofthe five spent medium levels), while another set of infections at each ofthe five levels of spent medium at infection received a 50%> fresh medium exchange 8-10 hpi. Each ofthe 293-ORF6 cell populations were infected with AdovTNF.l 1 vector particles when the cells reached an estimated density of 1.5x 10⁶ cells/mL. One half of the 293-ORF6 cell populations (one population infected with the AdovTNF.l 1 vector particles at each ofthe five levels of spent medium at infection) received a 50% fresh medium exchange 8-10 hpi. At 48 hpi, the cells were harvested, lysed, and the cell lysates were analyzed for AdovTNF.l 1 particle production by HPLC-PU assay using standard techniques. The results ofthe experiment are described in Table 6.

TABLE 6

[00327] The results ofthe above-described experiments, as reflected in Table 6, demonsfrate that a significant increase in AdovTNF.l 1 production is obtained in 293-ORF6 cells cultured in at least about 50%> spent medium, with or without a post infection fresh medium exchange. For example, at 50% spent medium in the culture at infection, the 293- ORF6 cells, with or without post-infection medium exchange, produced at least twice as many viral vector particles as cultures infected in greater than 50% fresh medium (significant, albeit less dramatic, increases were also observed when such cells received a fresh medium exchange after infection). The viral vector particle concentration increased further with higher concentrations of spent medium in the culture at infection. 293-ORF6 cells in 75% or 100% spent medium exhibited the highest yields of AdovTNF.l 1 vector particles.

[00328] In addition, the results demonstrate that when a medium exchange is performed at 8-10 hours post infection, however, adenoviral vector particle production increases dramatically, with a maximum increase at 100% spent medium during infection. The addition of a fresh medium exchange resulted in an increase in the amount of AdovTNF.l 1 vectors produced in cultures comprising 50%, 75%, and 100% spent medium at infection. [00329] These results demonstrate that the production of E4-deficient adenoviral vector particles in E4-ORF6-expressing HEK cells infected in at least about 50% spent medium (preferably about 75-100% spent medium) result in an increased yield of adenoviral vector particles compared to cells infected in lower levels of spent medium, suggesting the presence of substances in the cell culture spent media that promote the production of replication-deficient adenoviral vector particles. The results further demonstrate that E4- ORF6 expressing HEK cells infected in at least about 50% spent medium exhibit even higher yields of E4-deficient adenoviral vector particles when a medium exchange of about 50% is performed at about 8-10 hpi.

EXAMPLE 8 [00330] This example describes the determination of effective zinc concentrations for producing El -deficient, E4-deficient adenoviral vector particles in a population of complementing adenoviral packaging cells comprising an E4-ORF6 nucleic acid operably linked to a sheep metallothionein promoter.

[00331] 293-ORF6 cells were cultured in a serum-free medium using techniques described above. Six samples of cultured cells were prepared and contacted with one of six different zinc concentrations: 0 μM, 15 μM, 25 μM, 35 μM, 50 μM, and 100 μM at 24 hours prior to infection with a population of AdovTNF.11 vectors, as described above. The cells were then infected with a population of AdovTNF.l 1 vectors, harvested at 48 hpi, and the harvested cells were lysed using procedures described herein to obtain six adenoviral vector particle compositions. Average PU/cell and average FFU/cell were calculated for each ofthe six adenoviral vector particle compositions coπesponding to the six zinc concentrations tested. The results are shown in Table 7. TABLE 7

[00332] The results of these experiments, as reflected in Table 7, demonstrate that about 15-50 μM zinc is able to effectively induce expression of a metallothionein promoter-linked E4-ORF6 nucleic acid such that a population of E4-deficient viral vector particles is produced. The results further demonstrate that zinc concentrations of about 35-50 μM, and, more particularly, about 35 μM result in significantly improved AdovTNF.l 1 vector particle production in 293-ORF6 cells comprising a metallothionein-linked E4-ORF6 expression cassette. At a 50 μM concentration of zinc, large standard deviations in the average PU/cell and the average FFU/cell occuπed (data not shown), which could indicate some toxicity at zinc concentrations of about 50 μM or greater. At zinc concentrations of 100 μM, no FFUs were detected, suggesting that the zinc at this concentration was highly toxic to the 293-ORF6 cells.

[00333] The results of these experiments indicate that about 15-50 μM zinc can be used to induce expression of metallothionein promoter-linked E4 nucleic acid sequences in adenoviral vector particle complementing cells.

EXAMPLE 9 [00334] This experiment describes the determination of effective times for the addition of zinc to 293-ORF6 cells comprising a metallothionein promoter-linked E4-ORF6 expression cassette, as described in Example 8.

[00335] The 293-ORF6 cells were cultured in serum-free medium as described herein. Five samples ofthe cells were obtained and zinc was provided to reach a zinc concentration of 25 μM at either at 24 hours prior to infection, 4 hours prior to infection, 0 hours prior to infection (e.g., at infection), 4 hours post infection, or 24 hours post infection with AdovTNF.11 particles as described elsewhere herein. One set of cells was cultured and infected with no zinc added. Cells were harvested at 48 hours post infection (hpi) and lysed to produce an adenoviral vector particle composition as described herein. The average PU/cell was calculated for the compositions, coπesponding to the different time periods when the cells were contacted with the zinc. The results of these experiments are shown in Table 8.

TABLE 8

[00336] The results of these experiments as presented in Table 8 demonstrate that addition of zinc to induce ORF6 production in 293-ORF6 cells at least about 4 hours prior to infection results in a higher number of particle units produced per cell produced than when such cells are contacted with zinc after infection (particularly at 24 hpi). The results further reveal that the addition of zinc at about 24 hours prior to infection resulted in an average PU/cell ratio over double that achieved when zinc is added at 4 hours prior to infection. [00337] The results of this experiment demonstrate that addition of an inducer which upregulates an inducible promoter operably linked to a nucleic acid sequence that expresses an adenoviral gene function that complements an essential gene function of a replication- deficient adenoviral vector particle, at least about 4 hours, preferably about 24 hours, prior to infection with the adenoviral vector particles lacking the gene function complemented by the protein, is effective to produce a high yield of adenoviral vectors by inducing expression ofthe complementing protein while minimizing toxicity to the host cells.

EXAMPLE 10 [00338] This example describes prefeπed combinations of zinc induction and medium exchange for producing El -deficient, E4-deficient adenoviral vector particles in a population of complementing adenoviral packaging cells comprising an E4-ORF6 nucleic acid operably linked to a sheep metallothionein promoter.

[00339] 293-ORF6 cells were cultured in a serum-free medium using techniques described above. Samples of cultured cells were prepared and contacted with either 25 μM or 35 μM at either 24 hours prior to infection or at 0 hours prior to infection (i.e., at infection) with a population of El -deficient, E4-deficient adenoviral vector particles. The cells were then infected with a population of AdovTNF.11 vectors, harvested at 48 hpi, and the harvested cells were lysed using procedures described herein. The cells were either infected in 50% or 100% spent media and a medium exchange was performed as described herein either 8 hours post infection or 24 hours post infection. All combinations of conditions were analyzed. Average PU/mL was calculated for each of composition coπesponding to combinations of conditions tested. The results are shown in Table 9.

TABLE 9

[00340] The results of these experiments, as reflected in Table 9, demonstrate that about 25 μM zinc is an effective inducer of expression of a metallothionein promoter-linked E4- ORF6 nucleic acid, such that a large population of E4-deficient viral vector particles is produced in 293-ORF6 cells comprising such an E4-ORF6 expression cassette. The results further demonstrate that zinc administration at about24 hours prior to infection results in significantly improved AdovTNF.l 1 vector particle production in 293-ORF6 cells comprising a metallothionein-linked E4-ORF6 expression cassette. Furthermore, infection in 100% spent medium resulted in higher yields of AdovTNF.l 1 vector particles in the 293- ORF6 cells tested compared with infection in 50% spent medium, even in the controlled presence ofthe zinc inducer. Additionally, a medium exchange at about 8 hours post- infection in such a spent medium culture cultured under the controlled zinc induction levels still resulted in the highest levels of viral vector production in the cells tested. [00341] The results of these experiments indicate that contacting the cells with about 25 μM zinc 24 hours prior to infection in 100% medium and performing a medium exchange at about 8 hours post infection results in significant yield of E1-, E4-adenoviral vector particle production in 293-ORF6 cells comprising a metallothionein-linked E4-ORF6 expression cassette.

EXAMPLE 11 [00342] This example demonstrates the generation of an antibody-based assay for determining PEDF gene expression levels and the levels of PEDF transgene expression exhibited by a population of PEDF-expressing recombinant adenoviral vector particles produced according to the methods described herein.

[00343] Confluent cell cultures of A549 cells were washed and treated with trypsin. The cells were placed in centrifuge tubes and centrifuged for 5 minutes at 1000 φm. The cells were resuspended in culture medium and incubated for about 24 hours at 37°C, 5% CO₂. The cells were infected with AdovPEDF.10 or AdovPEDF.l 1 replication-deficient recombinant adenoviral vector particles (described in International Patent Application WO 01/58494) using standard techniques. After about 24 hours of incubation, the AdovPEDF.10 or AdovPEDF.l 1 infected cells were collected and spun at 1000 φm for 10 minutes. The supernatant was collected.

[00344] PEDF expression from the replication-deficient vectors encoding PEDF (AdovPEDF.10 or AdGvPEDF.ll) was determined by subjecting a sample ofthe supernatant to standard ELISA analysis using the directly conjugated polyclonal rabbit αPEDF that was developed specifically for the protocol using standard techniques. The optical density of each well was determined using a SPECTRAmax 340pc microplate reader set to 450 nm. Results were analyzed by the SOFTmax PRO computer program and PEDF expression levels were calculated. PEDF expression was readily detected. [00345] Levels of PEDF transgene expression also were measured by Western Blot. A sample ofthe cell supernatant was separated by SDS-PAGE and blotting was performed using standard techniques. PEDF was detected by the directly conjugated polyclonal rabbit αPEDF.

[00346] The results of these experiments demonstrate the production and purification techniques ofthe invention can be used to produce viral vector particles that exhibit a suitable level of transgene expression activity in suitable host cells.

EXAMPLE 12 [00347] This example demonstrates the increased adenovirus vector production in 293- ORF6 cells when the cells were infected with AdovTNF.l 1 vector particles, compared to 293-ORF6 cells infected with Ad_GVVEGF.l 1 vector particles.

[00348] The 293-ORF6 cells were cultured in 2 L Applikon bioreactors (Applikon, Inc.) in a fed-batch mode. When the cell densities in the bioreactors reached about 1.5 x 10 O 03/03945

107

cells/mL, the cells were taken from the bioreactors for infection. About 20 mL of cell culture in 125 mL shaker flasks were infected with either recombinant El -deficient, E4- deficient adenoviral vector particles comprising a human TNF-α gene sequence in place of the deleted El -region under the control of an EGR-1 promoter and a transcriptionally inert β-glucuronidase gene (spacer) in place ofthe deleted E4-region (AdovTNF.l 1 vector particles) or recombinant El -deficient, E4-deficient adenoviral vector particles comprising a human VEGF gene sequence under the control of a CMV promoter in place ofthe deleted El -region and a transcriptionally inert β-glucuronidase gene (spacer) in place ofthe deleted E4-region (AdovNEGF.l 1 vector particles). At 48 hpi, the cells were harvested, lysed, and the cell lysates were analyzed for AdovTNF.11 particle production and for AdovVEGF.11 particle production by standard HPLC-PU and FFU assay using standard techniques. [00349] Adherent 293-ORF6 cells were cultured using standard techniques and infected with either AdovTNF.11 vector particles or AdovVEGF.11 vector particles. At 48 hpi, the cells were harvested, lysed, and the cell lysates were analyzed for AdovTNF.l 1 particle production and for AdovVEGF.11 particle production by HPLC-PU and FFU assay using standard techniques. The results ofthe experiment are described in Table 10.

TABLE 10

[00350] The results of these experiments, as set forth in Table 10, demonstrate that a significant increase in AdovTNF.l 1 production is obtained in 293-ORF6 cells compared with the amount of Ad_GvTNF.11 production is obtained in 293-ORF6 cells in both medias tested.

[00351] The results demonstrate that the infection of 293-ORF6 cells with AdovTNF.11 vector particles expressing TNF-α at a level obtainable by EGR-1 expression in the absence of radiation-inducement results in an increased yield of adenoviral vector particles as measured by PU/cell and FFU/cell compared to 293-ORF6 cells infected with E1-, E4- adenoviral vector particles expressing some other growth factor (e.g., AdovVEGF.11) vector particles. The results further demonstrate that 293-ORF6 cells infected with either AdovTNF.11 vector particles or Ad_ϋvVEGF.11 vector particles experience a greater yield of adenoviral vector particles when the cells are propagated in suspension cell culture compared to adherent cell culture. EXAMPLE 13 [00352] This example demonstrates the use of an automated temperature monitoring and control system during the production of an adenoviral stock.

[00353] A lysate of adenoviral vector particle infected cells was obtained by subjecting the cells to microfluidization lysis. The cell lysate was clarified by microfiltration through a triple-microfilter clarification filter (pore sizes of about 8 μm, 3 μm, and 0.8 μm, respectively), and subjected to diafiltration by tangential flow filfration with nuclease digestion buffer (25mM Tris, lOmM NaCl, 5mM MgCl₂, 0.0025% polysorbate 80, pH 8) before the addition of Benzonase® (0.5-1.5U per 2 x 10⁴ cells). The reaction was incubated for 4 hours in a closed filtration system. The temperature was monitored and controlled by a programmable automatic temperature control system contained in the closed filfration system, which was set to 35° C for the Benzonase® reaction. The temperature ofthe reaction was separately manually monitored at 15 minute intervals from 0 to 4 hours after the addition ofthe Benzonase® to determine the effectiveness ofthe automatic temperature control system. This experiment was repeated and the results presented in Table 11.

TABLE 11

[00354] As is apparent from the data presented in Table 11 , the automated system kept the temperature in the closed system constant at 35° C with no significant fluctuation. The results of this experiment demonsfrate that automated programmable control systems are able to monitor and control operating parameters (e.g., temperature, pH, flow rate, pump output, pressure) and can be effectively used to produce adenoviral vector particle compositions under consistent conditions.

EXAMPLE 14 [00355] This example demonstrates the ability of an automated programmable system associated with a filfration system to monitor and adjust the fransmembrane pressure during the production of an adenoviral vector particle composition.

[00356] A lysate of adenoviral vector particle infected cells was produced by subjecting such cells to microfluidization lysis. The lysate was clarified by a triple-filter ultrafiltration filter system as described herein to obtain a filtered lysate. Benzonase® nuclease digestion buffer (25mM Tris, lOmM NaCl, 5mM MgCl₂, 0.0025% polysorbate 80, pH 8) was added to the filtered lysate and the lysate/digestion buffer solution was subjected to diafiltration using tangential flow filfration system (A/G UFP-500-C-9A ultrafiltration module) containing an programmable automatic control system which monitors and controls fransmembrane pressure. The automated pressure monitor was programmed to maintain fransmembrane at 2 bar for 20 minutes. The actual fransmembrane pressure was manually recorded at 2 minute intervals from 0 to 20 minutes. This experiment was repeated. The results of both experiments are presented in Table 12.

TABLE 12

[00357] As is evident from the data in Table 12, the automated pressure monitor and pressure control system was able to maintain a steady fransmembrane pressure with no significant pressure fluctuations. The results of these experiments indicate that automated systems for monitoring and controlling operating parameters such as filtration pressure can be effectively employed in the production of adenoviral vector particle compositions.

EXAMPLE 15 [00358] This example illustrates the removal of non- viral encapsidated DNA during the filfration step ofthe adenoviral production process by benzon nuclease digestion in combination with high salt filtration, organic solvent filfration, or the combination of high salt and organic solvent filtration.

[00359] An adenoviral vector particle composition was obtained by lysing adenoviral vector particle cells to obtain a cell lysate, subjecting the cell lysate to triple-microfilfration filter clarification filtration (pore sizes of about 8 μm, 3 μm, and 0.8 μm) to obtain a filtered lysate, subjecting the clarified lysate to diafiltration with a nuclease buffer using tangential flow filfration to obtain a nuclease buffer composition before the addition of Benzonase® (0.5-1.5U per 2 x 10⁴ cells), and subjecting the nuclease buffer composition to Benzonase® digestion at 35°C for about 4 hours. All ofthe aforementioned purification steps were performed in an integrated closed system in which the adenoviral vector particle composition was connected by sterilized steam block connectors. Eight samples ofthe adenoviral vector particle composition were obtained. Four ofthe samples were subjected to a second diafiltration with a tangential flow filter with either (1) a 600mM salt wash, (2) a IM salt wash, (3) a lOmM salt and 20% ethanol wash, or (4) a lOmM salt and 20% isopropanol wash. Total non-viral encapsidated DNA following the second filfration and particle units for each ofthe samples before and after the second diafiltration were determined using standard techniques. The results of these experiments are set forth in Table 13.

TABLE 13

b.d. = below detectable levels [00360] As is apparent from the data presented in Table 13, each ofthe high salt, organic solvent, and combination salt/organic solvent washes tested decreased the concentration of non- viral encapsidated DNA found in the starting material. The lOmM salt and 20% isopropanol wash resulted in the greatest reduction of non- viral encapsidated DNA (below the level of detection).

[00361] The above-described experiments demonstrate that high salt filtration, organic solvent filtration, and combination high salt/organic solvent filtration results in a decrease of non- viral encapsidated polynucleotide concentration in an adenoviral vector particle composition comprising at least about 6 x 10¹⁰ adenoviral vector particles without any appreciable loss in total adenoviral vector particles.

EXAMPLE 16 [00362] This example demonstrates the ability to filter adenoviral vector particle compositions by tangential flow ultrafiltration at shear rates of between about 6,000-24,000 sec^"1 while maintaining the activity ofthe infectious adenoviral vector particles. [00363] Adenoviral vector particle infected cell lysate, produced by microfluidization lysis, was clarified by a triple-filter ulfrafilfration filter system as described herein to obtain a filtered lysate, subjected to diafiltration with a nuclease buffer, and further subjected to Benzonase® digestion as described in Example 13. The nuclease buffer diafiltration and high salt diafiltration (with or without addition ofthe organic solvent) were performed by tangential flow filfration (A/G Technologies UFP-500-C-9A ultrafiltration module) at shear rates of 6,000, 12,000, 18,000, and 24,000 sec^"1. Samples ofthe high salt filtered composition were taken at 0, 10, 30 and 60 minutes. The number of focus forming units (FFU) in each ofthe samples was determined using standard techniques. The results of these experiments are presented in Table 14.

TABLE 14

[00364] The results of these experiments reflected in Table 14 demonsfrate that adenoviral vector compositions can be subjected to tangential flow filfration at shear rates of even about 12,000 sec^"1 and higher for up to 60 minutes while retaining high levels of active viral vector particles in the composition. Indeed, the results of these experiments indicate that shear rates as high as 24,000 sec^"1 over a 60 minute time period resulted in no significant loss of adenoviral vector particles capable of infection. Based on the results of these experiments, shear rates as high as about 32,000 sec^"1 are predicted to be acceptable during diafiltration.

EXAMPLE 17 [00365] This example demonstrates the ability ofthe storage compositions ofthe invention to effectively maintain a stable population of adenoviral vector particles during the viral vector particle production and/or purification processes. [00366] Adenoviral vector particle-infected cells were lysed by microfluidization as described herein to obtain a cell lysate. The cell lysate was clarified by microfiltration through a triple-filter clarification filter (the three filters comprising pore sizes of about 8 μm, about 3 μm, and about 0.8 μm, respectively), subjected to diafiltration by tangential flow filtration with a benzon nuclease buffer, and subjected to Benzonase® digestion at 35° C for 4 hours. The viral vector composition was further subjected to diafiltration by tangential flow filtration to obtain an adenoviral vector particle composition comprising a population of adenoviral vector particles in a temporary storage buffer (25mM Tris, 300mM NaCl, 5mM MgCl₂, 0.0025% polysorbate 80, 5% trehalose, pH 7.5). [00367] The adenoviral vector particle composition was maintained at about 4°C for 7 days in the temporary storage buffer. On Day 0, the adenoviral vector composition was divided into three 10 mL glass tubes to assay for the separation and precipitation ofthe adenoviral particles. Additionally, on day 3, 5, and 7, one ofthe tubes was tested for particle concentration (PU/mL) at the top and bottom ofthe tube using a standard particle unit assay technique.

[00368] At day 0, another portion ofthe adenoviral vector particle composition was placed in a sterile 5 OmL bag. A sample was aseptically removed from the sterile bag on day 3, day 5, and day 7 to assay for degradation ofthe viral particles. [00369] Visual inspection of the glass tubes showed no signs of settling or precipitation over the 7 day period. The particle numbers ofthe samples were identified by UV adsoφtion at 260nm and reverse phase HPLC. The results ofthe HPLC PU assay performed on the samples ofthe sterile bag composition showed no significant decrease in particle number over the 7 day test period. Approximate PU values at days 0, 3, 5, and 7 for this composition are presented in Table 15. TABLE 15

[00370] The number of infectious particles in the samples was determined by FFU assay. The number of infectious particles per mL (FFU/mL) was measured by standard techniques on Day 0 and 3. No significant change over the 3 day period in FFU level was observed. [00371] The results ofthe above-described experiments demonstrate the stability ofthe adenoviral vector particles in the temporary storage composition during a typical adenoviral vector particle production and purification process, and, thus, the suitability of such compositions for performing a hold or pause step in the production process. No significant change in the number of viral particles or infectious viral particles was observed at any of the times tested. These results demonsfrate that viral vector compositions can be stably stored in the temporary storage buffers ofthe invention for extended periods of time, during which the equipment ofthe automated closed production process can be assessed and repaired if required. Additionally, the stable storage ofthe adenoviral vector composition at intermediate stages in the adenoviral process allow testing ofthe suitability ofthe adenoviral vector product (e.g., by testing for the presence of adventitious agents) during the production or purification process.

EXAMPLE 18 [00372] This example demonstrates the effectiveness ofthe purification methods ofthe invention with respect to producing purified adenoviral vector particle compositions. [00373] A lysate of infected El -complemeting packaging cells was obtained by subjecting such cells to microfluidization lysis as described herein. A sample ofthe lysate was collected for later analysis. A second sample ofthe lysate was clarified by microfilfration through a triple-filter clarification filter (pore sizes of about 8 μm, 3 μm, and 0.8 μm, respectively), subjected to diafiltration by tangential flow filtration and to Benzonase® digestion at 35° C for 4 hours, and further subjected to diafiltration by tangential flow filtration to obtain a filtered adenoviral vector particle composition. The filtered adenoviral vector particle composition was subjected to liquid chromatography with a first ion exchange chromatography column comprising a Q Ceramic HyperD™ F chromatography resin as described in International Patent Application WO 99/54441. An eluate from the first ion exchange chromatography column was subjected to liquid chromatography with a second ion exchange chromatography column comprising a POROS D™ chromatography resin as described in the '441 PCT application. An eluate from the second ion exchange chromatography column comprising a purified adenoviral vector particle composition was obtained by UV absorbance at 260 nm and subjected to size-exclusion chromatography using a Sepharose™ 4 Fast Flow chromatography resin. An eluate from the size-exclusion chromatography resin was obtained and subjected to filtration using a 0.22 μm filter to yield a purified adenoviral vector particle composition. A sample ofthe purified adenoviral vector particle composition was obtained. The number of viral particles in the purified adenoviral vector particle composition sample and the crude cell lysate sample were determined by UV absorbance at 260 nm and anion exchange HPLC as described in the '441 PCT application.

[00374] The amount of non-viral encapsidated DNA 120 bp, 411 bp, and 757 bp in the purified composition sample and crude cell lysate sample was determined by TaqMan® quantitative real-time PCR (Perkin Elmer/ Applied BioSciences). The system works by using small primers that have a defined sequence as the strand that will be extended by the polymerase enzyme. These primers are designed to produce extended strands of DNA that have specific sizes. The 757 bp primers will produce a fragment of 757 bp. Any DNA fragment with the right sequences, even if it is longer than 757 bp, will serve as a template and result in PCR amplification. The amount ofthe amplification product is determined by the amount ofthe starting material. The three DNA bp sizes (757 bp, 411 bp, and 120 bp) are amplified as part ofthe assay. A fragment that is 1000 bp long will give products for all three sizes. A fragment of 500 bp will only react with the smallest two primer sets, and a fragment of 200 bp will only with the smallest one primer set. The results together allow one to quantify the intervening sizes. The results of these experiments are set out in Table 16.

TABLE 16

b.d. = below detected levels

[00375] As is evident from the data presented in Table 16, the methods ofthe present invention are capable of providing a purified adenoviral composition having less than about 10 ng of non- viral encapsidated DNA of about 750bp or more in length. Indeed, the results of these experiments indicate that the method ofthe invention can be employed to produce adenoviral vector particle compositions having less than about 10 ng of non- viral encapsidated DNA of about 120bp or more in length, effectively ensuring the absence of undesired foreign coding sequences (e.g., undesired host cell oncogene coding sequences). The results also indicate that the techniques ofthe invention can be used to provide a log reduction of about 3 logs or more in the amount of DNA in a crude host cell lysate.

EXAMPLE 19 [00376] This example demonstrates the benefits of purifying an adenoviral vector particle composition from crude cell lysate by utilizing a reverse flow elution technique during chromatography purification.

[00377] 293-ORF6 cells were grown and subsequently infected with Ad_Gv- 11 TNF in a solution comprising approximately 75% spent media at infection, as described in Example 7.

[00378] The infected cells were then processed by lysing the cells in a microfluidizer (Micro fluidics, Newton, Massachusetts) according to the manufacturer's directions and the lysate was subjected to clarifying by filtration. The clarified cell lysate was then treated with Benzonase® (Nycomed Pharma A/S, Denmark), according to the manufacturer's instructions, and diluted into a suitable buffer. [00379] The diluted cell lysate was subsequently applied to a Q Ceramic HyperD™ F column and eluted at 300 cm/hr with a step gradient of 360 to 475 mM NaCl. Fractions exhibiting a peak indicative ofthe presence of a population of adenoviral vector particles (measured by absorbance at 260 nm, as described in the above-referenced '441 PCT application) were collected and pooled to form the eluant.

[00380] The eluant from the Q Ceramic HyperD™ F column was diluted by about 30%, such that the NaCl elution agent was diluted to a concenfration less than the elution concentration used in purifying the eluant by a subsequent dimethylaminopropyl perfusive chromatography (POROS® 50D) column chromatography step. The POROS® 5OD column was loaded with the eluant in a first direction in a concentration of 300 mM NaCl and run through the column at a rate of about 500 cm/hr. Once the eluant had been added to the purification column, the flow rate was reduced to about 100 cm/hr and the adenoviral vector particle composition was eluted in a direction opposite ofthe first direction with a step gradient of NaCl (360 mM to 450 mM), such that the "top" ofthe column (the portion initially contacted with the eluant during loading and "forward flow" chromatography), which contains the highest concentration of bound adenoviral vector particles, was eluted first. This process is refeπed to as a reverse flow elution technique. Fractions exhibiting a resulting 260 nm UV absorbance peak were then collected and pooled to form a purified eluant.

[00381] The same process described above was performed without reducing the flow rate and without utilizing the reverse flow technique to elute the adenoviral vector particle composition from the purification column. This process is refeπed to as a forward flow elution technique.

[00382] Only one shaφ peak, indicative of a population of adenoviral vector particles in the purified eluant, was observed for each ofthe forward flow and reverse flow elution techniques, and only fractions representing these peaks were collected and pooled. The volume ofthe collected purified eluted fractions for both techniques were determined using standard techniques. When reverse flow elution was performed, it was discovered that the volume ofthe purified eluant was significantly reduced as compared to the purified eluant obtained by performing the forward flow elution technique under the same conditions. Indeed, the eluted fractions exhibiting the peak obtained by the reverse flow elution technique was in about 60% ofthe volume ofthe fractions exhibiting the peak obtained by the forward flow elution technique.

[00383] The results of this experiment demonstrate that reversing the flow when eluting the adenoviral vector particle composition from an affinity chromatography column (e.g., an ion exchange purification column) will result in a smaller volume of a more concentrated product than would a substantially identical process using a forward flow elution technique. In other words, by employing a reverse flow elution technique in a chromatography purification process, the volume eluted from the chromatography column is reduced as compared to using the forward flow elution technique. Reducing the volume concentrates the adenoviral vector particle composition and will ideally allow for more ofthe adenoviral vector particles to be loaded and subsequently eluted from a size-exclusion chromatography column.

[00384] All references, including publications, patent applications, and patents, cited herein are hereby incoφorated by reference to the same extent as if each reference were individually and specifically indicated to be incoφorated by reference and were set forth in its entirety herein.

[00385] The use ofthe terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context ofthe following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Terms such as "including," "having," "comprising," "containing," and the like are to be construed as open-ended terms (i.e., meaning "including, but not limited to") unless otherwise indicated, and as encompassing the phrases "consisting of and "consisting essentially of." Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value ofthe range, unless otherwise indicated herein, and each separate value is incoφorated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope ofthe invention unless otherwise claimed. No language in the specification should be construed as indicating any non- claimed element as essential to the practice ofthe invention.

[00386] The citation of any patent or patent document herein does not reflect any view concerning the patentability ofthe subject matter described or claimed in such patent documents. Rather, such patent documents may be cited merely to provide convenient reference for suitable techniques and compositions, including techniques and compositions otherwise well known in the art.

[00387] Any ofthe techniques and any ofthe characteristics ofthe viral vector particle compositions ofthe invention can be combined in any suitable manner, unless otherwise stated or clearly contradicted by context.

[00388] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those prefeπed embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents ofthe subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination ofthe above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

WHAT IS CLAIMED IS:

1. A method of producing an adenoviral vector composition comprising providing a culture comprising a population of human embryonic kidney (HEK) cells and at least about 50% spent culture media, infecting the cells with a population of adenoviral vector particles, and lysing the cells to obtain an adenoviral vector composition.

2. The method of claim 1, wherein the amount of adenoviral vector particles in the adenoviral vector composition is greater than the number of adenoviral vector particles in a composition produced by performing the method with a culture comprising a substantially identical population of cells and less than about 50% spent media.

3. The method of claim 1 , wherein the cells are propagated in at least about 75% spent media.

4. The method of any of claims 1-3, wherein the HEK cells comprise a nucleic acid sequence encoding a portion ofthe E4 region ofthe adenoviral genome comprising E4- ORF6 and the adenoviral vector is a replication-deficient adenoviral vector comprising a genome which lacks at least a portion ofthe E4 region ofthe adenovirus genome.

5. The method of claim 4, wherein the HEK cells comprise a second nucleic acid encoding a protein that complements for an El gene function and the adenoviral vector particle comprises a genome deficient in the El gene function complemented by the protein.

6. The method of claim 5, wherein the adenoviral vector particle is deficient in all regions ofthe adenoviral genome responsible for replication.

7. The method of any of claims 1 -6, wherein the culture comprises at least about 75% spent media.

8. The method of claim 7, wherein the culture comprises at least about 90% spent media.

9. The method of claim 8, wherein the culture comprises about 100% spent media.

10. The method of any of claims 1 -9, wherein the culture is a suspension cell culture and the culture medium is serum-free medium, animal protein-free medium, or chemically-defined medium.

11. The method of any of claims 1-10, wherein fresh medium is added to the culture at about 4-30 hours after infecting the cell with the adenoviral vector particles, such that the amount of fresh medium in the culture is at least about 50%- 100%) ofthe total medium in the culture.

12. The method of claim 11 , wherein the medium has a cell density of at least about 1 10 when the fresh medium is added to the culture.

13. A method of producing a replication-deficient adenoviral vector composition comprising providing a culture comprising a population of adenovirus packaging cells containing a nucleic acid encoding a portion ofthe E4 region comprising E4-ORF6 and at least about 50% spent culture media, infecting the cells with an E4-defϊcient adenoviral vector particle, and lysing the cells to obtain a replication-deficient adenoviral vector composition.

14. The method of claim 13 , wherein the amount of replication-deficient adenoviral vector particles in the adenoviral vector composition is greater than the number of replication-deficient adenoviral vector particles in a composition produced by performing the method with a culture comprising a substantially identical population of cells and less than about 50% spent media.

15. The method of claim 13, wherein the cells are propagated in at least about 75% spent media.

16. The method of any of claims 13-15, wherein the cells are human embryonic kidney (HEK) cells, human embryonic retinal (HER) cells, human retinal cells, human embryonic lung (HEL) cells, lung carcinoma cells, or kidney carcinoma cells.

17. The method of any of claims 13-16, wherein the culture comprises at least about 75% spent media.

18. The method of claim 17, wherein the culture comprises at least about 90%> spent media.

19. The method of claim 18, wherein the culture comprises about 100% spent media.

20. The method of any of claims 13-19, wherein the fresh medium is added to the culture at about 4-30 hours after infecting the cell with the adenoviral vector particles, such that the amount of fresh medium in the culture is at least about 50%- 100% ofthe total medium in the culture.

21. The method of claim 20, wherein the medium has a cell density of at least about 1 x 10 when the fresh medium is added to the culture.

22. The method of any of claims 13-20, wherein the HEK cells comprise a second nucleic acid encoding a protein that complements for an El gene function and the adenoviral vector particle comprises a genome deficient in the El gene function complemented by the protein.

23. The method of claim 22, wherein the adenoviral vector particle is deficient in all regions ofthe adenoviral genome responsible for replication.

24. The method of any of claims 13-23, wherein the culture is a suspension cell culture and the culture medium is serum-free medium, animal protein-free medium, or chemically-defined medium.

25. The method of claim 24, wherein the serum-free medium is SFMII.

26. A method of producing an adenoviral vector particle composition comprising culturing a population of adenoviral packaging cells in a media comprising at least about 5- 50 ng/ml of an EGF, about 5-50 ng/ml of an IGF, or both, infecting the cells with an adenoviral vector particle, and culturing the cells to produce an adenoviral vector particle composition.

27. The method of claim 26, wherein the medium contains about 10 ng/ml of an EGF and about 10 ng/ml of an IGF.

28. The method of claim 25 or claim 26, wherein at least about 2.9 x 104 adenoviral vector particle units/cell are obtained at harvest.

29. The method of any of claims 25-28, wherein the presence ofthe EGF, IGF, or both, results in an at least about 20% increase in particle unit/cell yield at harvest over culturing the cells in a substantially identical media without the EGF, IGF, or both.

30. The method of claim 29, wherein the presence ofthe EGF, IGF, or both, results in an at least about 80% increase in particle unit/cell yield at harvest over culturing the cells in a substantially identical media without the EGF, IGF, or both.

31. The method of any of claims 25-30, wherein the cells are infected when the density of cells in the medium is about 40-70% ofthe density ofthe cells obtained in the medium when the growth ofthe culture is in the stationary phase.

32. The method of any of claims 25-30, wherein the cells are harvested between 36 and 60 hours post-infection.

33. The method of claim 32, wherein the cells are harvested at about 48 hours post-infection.

34. The method of any of claims 25-33, wherein the number of adenoviral vector particles produced is at least about 10% greater than in a substantially identical medium, cultured under substantially identical conditions, without the EGF, IGF, or both.

35. The method of any of claims 25-34, wherein the medium produces a culture with a maximum cell density of about 2 x 10⁶ cells/ml to about 4 x 10⁶ cells/ml in a fed- batch mode.

36. The method of any of claims 25-35, wherein the medium comprises 293 SFMII medium.

37. The method of any of claims 25-36, wherein the cell is a human embryonic kidney cell, human embryonic retinal cell, human retinal cell, human embryonic lung cell, lung carcinoma cell, or kidney carcinoma cell.

38. The method of any of claims 25-37, wherein the cell comprises a portion of an adenoviral genome.

39. The method of claim 38, wherein the portion ofthe adenoviral genome is the El and the E4-ORF6 regions.

40. The method of any of claims 25-29, wherein the cells are serum-free medium-adapted human embryonic kidney cells in suspension culture.

41. The method of claim 40, wherein the cells are derived from the 293 cell line.

42. The method of claim 41, wherein the cells are 293-ORF6 cells.

43. A method of producing adenoviral vector particles comprising culturing cells infected with adenoviral vectors in a culture medium containing r-insulin, dextran sulfate, and a pluronic, which is free of α-Tocopheral Acetate, cod liver oil, or both, in the presence of at least about 1 ng/mL of an EGF, at least about 1 ng/mL of an IGF, or both.

44. The method of claim 43, wherein the medium is a serum-free medium.

45. The method of claim 44 wherein the medium is an animal protein- free medium.

46. The method of any of claims 43-45, wherein the medium comprises at least about 5 ng/ml of an EGF and at least about 5 ng/ml of an IGF.

47. A cell culture comprising:

(a) an adenoviral packaging cell,

(b) a medium containing r-insulin, dextran sulfate, a pluronic, and glutamine, in amounts sufficient to support the growth ofthe cell and production of adenoviral vector particles, and

(c) an amount of an EGF, an IGF, or both, sufficient to increase the per cell yield of adenoviral vector particles by at least about 20%, wherein the cell culture is free from α-Tocopheral Acetate, cod liver oil, or both.

48. The culture of claim 47, wherein the medium is a serum-free medium.

49. The culture of claim 48, wherein the medium is an animal protein-free medium.

50. The culture of claim 47, wherein the medium comprises SFMII medium, CD293 medium, GTRB medium, or combination thereof, to which about 1-50 ng/ml of an EGF, about 1-50 ng/ml of an IGF, or both, has been added.

51. The culture of claim 50, wherein the medium comprises SFMII medium.

52. A method of producing adenoviral vector particles comprising:

(a) culturing cells capable of supporting the growth of adenoviral vectors in a culture for at least about 2 hours of exponential growth,

(b) administering about 5-50 ng/ml of an EGF, about 5-50 ng/ml of an IGF, or both to the culture,

(c) infecting the cells with an adenoviral vector,

(d) culturing the cells for a period sufficient to produce a desired yield of adenoviral vectors, and

(e) harvesting adenoviral vectors from the culture.

53. The method of claim 52, wherein the method comprises administering about 5-50 ng/ml of an EGF and about 5-50 ng/ml of an IGF to the medium.

54. The method of claim 53, wherein the method comprises administering about 10 ng/ml of an EGF and about 10 ng/ml of an EGF to the medium.

55. The method of any of claims 52-54, wherein the cells are infected with the adenoviral vector after a period of at least about four hours of exponential growth but before seven doublings ofthe culture.

56. The method of any of claims 52-55, wherein the cells are human embryonic kidney cells, human embryonic retinal cells, human retinal cells, human embryonic lung cells, lung carcinoma cells, or kidney carcinoma cells.

57. The method of any of claims 52-56, wherein the cells are El, E4- complementing cells.

58. The method of claim 57, wherein the cells comprise the El and the E4-ORF6 regions ofthe adenoviral genome.

59. The method of any of claims 52-58, wherein the medium produces a culture with a maximum cell density of about 2 x 10⁶ cells/ml to about 4 x 10⁶ cells/ml in a fed- batch mode.

60. A method of producing a population of replication-defective adenoviral vector particles comprising:

(a) providing a cell culture comprising a population of adenovirus packaging cells comprising a nucleic acid sequence that encodes a protein which complements at least one adenovirus gene function, wherein the nucleic acid sequence is operably linked to a transcription control element that is upregulated in the presence of an inducer and the protein is toxic to the cells,

(b) adding the inducer to the culture at a time relative to the time of infecting the cells with a population of an adenoviral vector particles such that the inducer has minimum toxic effects on host cells, results in a higher yield of adenoviral vector particles being produced by the cells, or both, and in an amount such that the transcription control element is detectably upregulated,

(c) infecting the cells with a population of replication-deficient adenoviral vector particles which comprise an adenoviral genome defective in at least one gene function complemented by the protein, and

(d) culturing the cells such that the cells produce a population of replication-deficient adenoviral vector particles.

61. The method of claim 60, wherein the cells are human embryonic kidney cells, human embryonic retinal cells, human retinal cells, human embryonic lung cells, lung carcinoma cells, or kidney carcinoma cells.

62. The method of claim 60, wherein the cell culture is a serum-free suspension culture or an animal protein-free suspension culture.

63. The method of any of claims 60-62, wherein the method comprises administering about 5-50 ng/ml of an EGF and about 5-50 ng/ml of an IGF to the medium.

64. The method of any of claims 60-63, wherein the nucleic acid comprises a portion ofthe E4 region ofthe adenovirus genome comprising E4-ORF6.

65. The method of any of claims 60-64, wherein the transcription control element is a metallothionein promoter.

66. The method of claim 65, wherein the metallothionein promoter is a sheep metallothionein promoter

67. The method of claim 65 or claim 66, wherein the inducer is zinc.

68. The method of claim 67, wherein the zinc is added to the culture to obtain a zinc concenfration of about 5 μM to about 100 μM at the time of about 0 to 48 hours before the cell culture is infected with the defective adenoviral vector particle.

69. A method of producing a population of E4-deficient adenoviral vector particles comprising:

(a) providing a cell culture comprising a population of adenovirus packaging cells comprising a nucleic acid sequence encoding at least part ofthe E4 region ofthe adenovirus genome including E4-ORF6, wherein the nucleic acid sequence is operably linked to a metallothionein promoter,

(b) adding zinc to the culture to obtain a zinc concentration of about 15 μM to about 50 μM at about 4 to 36 hours before infecting the cells with a population of E4-deficient adenoviral vector particles,

(c) infecting the cells with a population of E4-deficient adenoviral vector particles, and

(d) culturing the cells such that the cells produce a population of E4- deficient adenoviral vector particles.

70. The method of claim 69, wherein the cells are human embryonic kidney cells, human embryonic retinal cells, human retinal cells, human embryonic lung cells, lung carcinoma cells, or kidney carcinoma cells.

71. The method of claim 69 or claim 70, wherein the cells comprise a second nucleic acid sequence encoding a protein that complements for an adenoviral El gene function.

72. The method of any of claims 69-71 , wherein the cell culture is a serum-free and/or an animal protein free suspension culture.

73. The method of any of claims 69-72, wherein the method comprises administering about 5-50 ng/ml of an EGF and about 5-50 ng/ml of an IGF to the medium.

74. The method of any of claims 69-73, wherein the metallothionein promoter is a sheep metallothionein promoter.

75. The method of any of claims 69-74, wherein the cells are 293/ORF6 cells.

76. The method of any of claims 69-75, wherein the zinc concenfration is about 20-30 μM.

77. The method of any of claims 69-77 wherein the zinc is added at approximately 12 - 28 hours before infecting the cells with the E4-deficient adenoviral vector particle.

78. A method for preparing an adherent culture of a cell culture comprising a population of adherent adenoviral vector packaging cells adapted to a serum-free suspension culture which efficiently express a nucleic acid that complements an adenovirus gene function to an animal protein-free suspension culture comprising:

(a) providing a monolayer of adenoviral vector packaging cells comprising a nucleic acid encoding a protein that complements at least one adenovirus gene function transcriptionally linked to an antibiotic resistance gene,

(b) washing the cell monolayer with a saline buffer,

(c) adding an serum- free medium to the cell monolayer in an amount sufficient to propagate the cells at a cell density less than the cell density of a culture ofthe cells in the lag phase,

(d) incubating the cells with the serum-free medium,

(e) applying an antibiotic or antibiotic analog to the cells such that cells not carrying the antibiotic resistance gene do not propagate, and

(f) resuspending the cells in an serum-free medium with continuous shaking, rocking, or rolling such that a population of adenoviral vector packaging cells efficiently expressing a nucleic acid complementing an adenovirus gene function and that are adapted to an serum medium is obtained.

79. The method of claim 78, wherein the cells are incubated in about 5% to about 10% CO₂.

80. The method of claim 79, wherein the cells are incubated in about 5% CO₂.

81. The method of any of claims 78-80, wherein the saline buffer is phosphate buffered saline.

82. The method of any of claims 78-81 , wherein the antibiotic is puromycin.

83. The method of any of claims 78-82, wherein the serum-free cell media comprises at least about 10 ng/mL of an IGF and at least about 10 ng/mL of an EGF.

84. The method of any of claims 78-83, wherein the cells are human embryonic kidney cells, human embryonic retinal cells, human retinal cells, human embryonic lung cells, lung carcinoma cells, or kidney carcinoma cells.

85. The method of any of claims 78-84, wherein the cells comprise at least a portion ofthe ORF6 region ofthe E4 region ofthe adenoviral genome.

86. The method of claim 85, wherein the cells comprise at least a portion ofthe El region and at least a portion ofthe E4-ORF6 region ofthe adenoviral genome.

87. A method of producing a population of complementary adenoviral packaging cells infected with replication-deficient adenoviral vectors, which method comprises:

(a) providing a population of at least about lx 10⁶ total adenoviral vector packaging cells in a medium,

(b) expanding the cells to at least about 1x 10^s total cells,

(c) further expanding the cells in at least one bioreactor to at least about I x lO⁹ total cells, and

(d) infecting the cells with viral vectors.

88. The method of claim 87, wherein the adenoviral vector particles are further purified by filfration, chromatography, or both.

89. The method of claim 87 or claim 88, wherein the cells are expanded in a first bioreactor and wherein the cells are then subsequently transfeπed to a second bioreactor and further expanded.

90. The method of any of claims 87-89, wherein the cells are expanded to at least about 1 x 10¹⁰ cells before infection.

91. The method of any of claims 87-90, wherein the cells are suspension cells grown in an animal protein-free medium.

92. The method of any of claims 87-90, wherein the adenoviral vector particles are harvested at about 48 hours after infection.

93. The method of claim 92, wherein the adenoviral vector particles are harvested at about 36 hours after infection.

94. The method of any of claims 87-93, wherein the adenoviral vector particles comprise a heterologous nucleic acid sequence.

95. The method of any of claims 87-94, wherein the adenoviral vector particle is a replication-deficient adenoviral vector.

96. The method of claim 95, wherein the adenoviral vector particle is deficient in a gene function ofthe E4 region ofthe adenoviral genome and at least one other gene function ofthe adenoviral genome.

97. The method of claim 95 or claim 96, wherein the adenoviral vector particle is deficient in a gene function ofthe El region.

98. The method of any of claims 95-97, wherein the adenoviral vector particle is deficient in a gene function ofthe El region and a gene function ofthe E3 region ofthe adenoviral genome.

99. The method of claim 95, wherein the adenoviral vector particle is deficient in all regions ofthe adenoviral genome responsible for replication.

100. The method of any of claims 95-98, wherein the adenoviral vector particle is deficient in a late region ofthe adenoviral genome.

101. The method of any of claims 87-100, wherein the cells are human embryonic kidney cells, human embryonic retinal cells, human retinal cells, human embryonic lung cells, lung carcinoma cells, or kidney carcinoma cells.

102. The method of any of claims 87-101, wherein the cells are E4- complementing cells.

103. The method of claim 102, wherein the cells comprise the ORF6 region ofthe E4 region ofthe adenoviral genome.

104. The method of claim 94, wherein the heterologous nucleic acid sequence encodes a protein.

105. The method of claim 104, wherein the protein encodes tumor necrosis factor- α, a vascular endothelial growth factor, a pigment-epithelial derived factor, or an atonal- associated factor.

106. The method of any of claims 87- 105, wherein the medium comprises at least about 10 ng/mL of an IGF, at least about 10 ng/mL of an EGF, or both.

107. A method of lysing adenoviral vector infected cells comprising providing a culture comprising a population of adenoviral vector infected cells and lysing the cells by subjecting the culture to microfluidization at a pressure of about 500-1500 psi.

108. The method of claim 107, wherein the microfluidization pressure is about 1000 psi.

109. The method of claim 106 or claim 107, wherein the culture comprises at least about 2 x l0⁶ cells/mL.

110. The method of any of claims 107- 109, wherein the cells are lysed in a period of about 30 minutes or less.

111. The method of any of claims 107- 110, wherein the culture is subj ected to the microfluidizer at a rate of about 2.5 L/min.

112. A method of producing a filtered adenoviral vector particle composition comprising providing an adenoviral composition comprising a population of adenoviral vector particles and subjecting the adenoviral vector particle composition to filtration at a rate such that the shear is at least about 11,000 sec^"1 to obtain a filtered adenoviral vector particle composition.

113. The method of claim 112, wherein the shear is about 11,000 sec^"1 to about 32,000 sec^"1.

114. The method of claim 113, wherein the shear is about 13,000 sec^"1 to about 28,000 sec^'1.

115. The method of claim 114, wherein the shear is about 15,000 sec^"1 to about 24,000 sec^"1.

116. The method of claim 115, wherein the shear is about 18,000 sec^"1.

117. The method of any of claims 112-116, wherein the shear is generated by the rate of liquid flow in a tangential flow filfration system.

118. The method of any of claims 112-117, wherein the method comprises subjecting the filtered adenovirus composition to filtration with more than one filter at a flow rate such that the shear is at least about 11,000 sec^"1.

119. The method of any of claims 112-117, wherein the filtration is diafiltration.

120. The method of claim 119, wherein the diafiltration is performed at 18-25°C.

121. The method of any of claims 112-120, wherein the method comprises subjecting the adenoviral vector particle composition, the filtered adenoviral vector particle composition, or both to nuclease digestion.

122. The method of claim 121, wherein the nuclease is benzon nuclease and the digestion is performed at about 34-36° C.

123. The method of any of claims 112- 122, wherein the adenoviral vector particle composition maintains an ionic sfrength of about 0.5-1.2M for a sufficient period of time before subjecting the composition to filtration, such that the filtered adenoviral vector particle composition comprises less non-viral-encapsidated polynucleotide than the adenoviral vector particle composition.

124. The method of claim 123, wherein the ionic strength is obtained by adding one or more monovalent salts, divalent salts, polyvalent salts, or combinations thereof.

125. The method of claim 124, wherein the ionic strength is obtained by adding about 0.5-1.2 M NaCl to the composition.

126. The method of any of claims 112-122, wherein the adenoviral vector particle composition comprises about 5-20% (v/v) of an organic solvent for a sufficient period of time before subjecting the composition to filtration, such that the filtered adenoviral vector particle composition comprises less non-viral-encapsidated DNA than the adenoviral vector particle, less active enveloped virus particles than the filtered adenoviral vector particle composition, less lipid than the adenoviral vector particle composition, or any combination thereof.

127. The method of claim 126, wherein the organic solvent is a non-polar organic solvent.

128. The method of claim 127, wherein the non-polar organic solvent is tri-n- butyl-phosphate.

129. The method of claim 126, wherein the organic solvent is a CrC₆ alcohol.

130. The method of claim 129, wherein the organic solvent is ethanol or isopropanol.

131. A method of producing a filtered adenoviral vector particle composition comprising providing an adenoviral vector particle composition comprising a population of adenoviral vector particles and at least one undesired biomolecule and subjecting the adenoviral vector particle composition to ultrafiltration at a rate such that the shear is at least about 5,000 sec^"1 to obtain a filtered adenoviral vector particle composition, wherein the amount ofthe undesired material in the filtered adenoviral composition is less than in the adenoviral vector particle composition.

132. The method of claim 131, wherein the shear is about 5,000 sec^"1 to about 32,000 sec^"1.

133. The method of claim 132, wherein the shear is about 10,000 sec^"1 to about 28,000 sec^"1.

134. The method of claim 133, wherein the shear is about 15,000 sec^"1 to about 24,000 sec^"1.

135. The method of claim 134, wherein the shear is about 18,000 sec^"1.

136. A method of preparing a purified adenoviral vector particle composition comprising filtering an adenoviral vector particle composition through a closed filfration system comprising an interconnected assembly of a clarification filter and a tangential flow filtration filter to obtain a purified adenoviral vector particle composition.

137. The method of claim 136, wherein the clarification filter is a depth filtration filter.

138. The method of claim 136, wherein the clarification filter is a microfiltration filter.

139. The method of any of claims 136-138, wherein the tangential flow filfration filter is a hollow fiber filter.

140. The method of any of claims 136-139, wherein the clarification filter comprises an interconnected assembly comprising a first filter, a second filter, and a third filter, wherein the first filter is positioned at the end ofthe assembly first contacted with the adenoviral vector particle composition and the third filter is the positioned at the end ofthe assembly last contacted with the adenoviral vector particle composition, the pores ofthe first filter are larger in diameter than those ofthe second filter, and the pores ofthe second filter are larger in diameter than those ofthe third filter.

141. The method of claim 140, wherein the pore sizes are about 8μm, 3μm, and 0.8μm, for the first filter, second filter, and third filter, respectively.

142. The method of any of claims 136-141, wherein the method further comprises subjecting the adenoviral vector particle composition to nuclease digestion within the closed filfration system.

143. The method of claim 142, wherein the adenoviral vector particle composition is subjected to the endonuclease digestion after the adenoviral vector particle composition is filtered by the clarification filter.

144. The method of any of claims 136-143, wherein the method comprises increasing the ionic strength ofthe adenoviral vector particle composition at least about 0.05M, contacting the adenovirus with an organic solvent, or bothr

145. The method of any of claims 136-144, wherein the method further comprises maintaining the adenoviral particle in about 1-25% trehalose, 0.001-0.015% polysorbate 80, 10-65mM arginine, or a combination thereof.

146. The method of any of claims 136- 145, wherein the clarification filter is contacted with a composition comprising at least about 1%> (wt./vol.) polysorbate 80 before the adenoviral vector particle composition is filtered by the clarification filter.

147. The method of claim 146, wherein the tangential flow filtration filter is contacted with a composition comprising at least 0.001% polysorbate 80, but having a concentration of polysorbate 80 lower than the concentration ofthe composition contacted with the clarification filter, before the adenoviral vector particle composition is filtered by the tangential flow filtration filter.

148. A method of preparing a purified viral vector composition comprising:

(a) providing a viral vector composition comprising a population of viral vector particles,

(b) increasing the ionic strength ofthe composition to at least about 0.5 M to form an increased ionic strength composition, and

(c) subjecting the increased ionic sfrength composition to tangential flow filfration to obtain a filtered composition, wherein the filtered composition comprises less non-viral vector particle-encapsidated DNA, non- viral particle component protein, or both, than the viral vector particle composition.

149. The method of claim 148, wherein the method comprises increasing the ionic strength concenfration to about 0.5-1.2 M to form the increased ionic strength composition.

150. The method of any of claims 148-149, wherein the ionic sfrength is increased by the addition of one or more selected from the group consisting of monovalent salts, divalent salts, and polyvalent salts.

151. The method of any of claims 148-150, wherein the monovalent salt is NaCl.

152. The method of any of claims 148-151, wherein the tangential flow filtration is performed using a hollow fiber tangential flow filfration system.

153. The method of any of claims 148-152, wherein the nominal molecular weight cutoff (NMWCO) ofthe filter membranes in the tangential flow filfration system is about 30-1,000 kDa.

154. The method of claim 153, wherein the NMWCO is about 500 kDa.

155. The method of any of claims 148-154, wherein the shear rate is about 5,000- 32,000 sec^"1.

156. A method of preparing a purified viral vector composition comprising:

(a) providing a viral vector composition comprising a population of viral vector particles,

(b) increasing the ionic strength ofthe composition to at least about 0.5 mM to form an increased ionic strength composition,

(c) increasing the organic solvent concentration to at least about 5% (v/v) of a Ct-Cβ alcohol, and

(d) subjecting the increased ionic sfrength and increased organic solvent composition to tangential flow filtration to obtain a filtered composition, wherein the filtered composition comprises less non-viral-encapsidated DNA, non- viral protein, or both, than a substantially identical composition subjected to substantially identical tangential flow filtration at a lower ionic sfrength, a lower organic solvent concenfration, or both.

157. The method of claim 156, wherein the ionic sfrength is at least about 10 mM and the organic salt concentration is at least 20% (v/v) of a C C₆ alcohol.

158. The method of claim 156 or claim 157, wherein the ionic sfrength is increased by the addition of one or more selected from the group consisting of monovalent salts, divalent salts, and polyvalent salts

159. The method of claim 158, wherein the monovalent salt is NaCl.

160. The method of any of claims 156-159, wherein the -Cβ alcohol is ethanol, isopropanol, or a combination thereof.

161. A method of preparing a purified viral vector composition comprising providing a viral vector composition comprising a population of viral vector particles and subjecting the composition to benzon nuclease digestion at about 34-36° C for a period of time to obtain a purified viral vector composition which comprises less non-viral- encapsidated DNA than the viral vector composition, wherein at least 90% ofthe viral activity is maintained.

162. The method of claim 161, wherein the benzon nuclease digestion is performed for at least about 4 hours.

163. The method of claim 161 or claim 162, wherein the benzon nuclease digestion is performed at about 35° C.

164. The method of any of claims 161-163, wherein the method further comprises subjecting the viral vector composition, purified viral vector composition, or both, to tangential flow ultrafiltration.

165. The method of any of claims 161 - 164, wherein the amount of non-viral- encapsidated DNA in the further purified composition is at least about 2 logs less than the amount of non-viral-encapsidated DNA in the viral vector composition.

166. The method of any of claims 161-165, wherein benzon nuclease digestion is performed in about composition with an ionic strength of about 10-75 mM.

167. The method of claim 166, wherein the ionic sfrength is 10 mM.

168. A method for preparing a purified adenoviral vector particle comprising: filtering an adenoviral vector composition comprising a population of adenoviral vector particles with a filter derivatized with a composition selective for removal of lipids, surfactants, or both, with respect to other biomolecules, such that a purified adenoviral vector particle composition is obtained, wherein the amount of lipids, surfactants, or both in the purified adenoviral vector composition is less than in the adenoviral vector composition.

169. The method of claim 168, wherein the composition is a silica.

170. The method of claims 168, wherein the composition comprises a silica.

171. The method of any of claims 169- 170, wherein the composition imparts a positive charge to the filter.

172. The method of any of claims 168-171, wherein the filter is a clarification microfiltration filter.

173. The method of any of claims 168-172, wherein the method further comprises subjecting the purified adenoviral vector composition to an anion exchange chromatography column comprising a resin functionalized with a tertiary or quaternary amine binding moiety that is more selective for adenoviral vector particles than DEAE, and eluting at least a portion ofthe purified adenoviral vector composition to obtain an ion exchange chromatography purified composition.

174. The method of any of claims 168- 173 , wherein the method further comprises subjecting the ion exchange chromatography purified composition to a size-exclusion chromatography column and eluting a portion ofthe ion exchange chromatography composition to obtain a size purified composition.

175. The method of any of claims 168- 174, wherein the method further comprises subjecting the purified adenoviral vector particle composition to a chromatography column comprising a chromatography resin functionalized with a binding moiety selective for lipids, surfactants or both, with respect to adenoviral vector particles other non-lipid biomolecules, or both, and eluting at least a portion ofthe adenoviral vector particle composition from the chromatography column to obtain a chromatography purified adenoviral vector particle composition.

176. A method for preparing a purified adenoviral vector particle composition comprising:

(a) subjecting an adenoviral vector composition comprising a population of adenoviral vector particles to a chromatography column comprising a chromatography resin functionalized with a binding moiety selective for removal of lipids, surfactants, or both, with respect to adenoviral vector particles, other non- lipid biomolecules, or both, and

(b) eluting at least a portion ofthe composition from the chromatography column comprising a population of adenoviral vector particles to obtain a purified adenoviral vector particle composition, wherein the amount of lipids, surfactants, or both in the purified adenoviral vector particle composition is less than in the adenoviral composition.

177. The method of claim 176, wherein the resin is an anion exchange chromatography resin.

178. The method of claim 177, wherein the anion exchange chromatography resin comprises a silica selective for lipids, surfactants, or both.

179. The method of any of claims 176- 178, wherein the resin is a gel filtration resin.

180. The method of claim 179, wherein the gel filtration resin comprises a binding moiety comprising at least one hydroxylpropyl group.

181. The method of any of claims 176-180, wherein the adenoviral vector composition comprises TNBP when the composition is subjected to the chromatography column.

182. The method of any of claims 176-181, wherein the adenoviral vector composition comprises about 0.3% TNBP.

183. The method of any of claims 176- 182, wherein the method further comprises subjecting the purified adenoviral vector composition to size-exclusion chromatography to obtain a size purified adenoviral vector composition.

184. The method of claim 183, wherein the method further comprises subj ecting the size purified adenoviral vector composition to filtration to obtain a bulk drug substance.

185. A method for preparing a purified adenoviral vector particle composition comprising;

(a) obtaining an adenoviral vector particle composition comprising a population of adenoviral vector particles and an undesired biomolecule,

(b) preparing a packed size-exclusion chromatography (SEC) column by packing an SEC resin in a column at a rate of at least about 1.5 times the flow rate used for passing an adenovirus composition through the packed SEC column, and

(c) loading the adenoviral vector particle composition onto the packed SEC column,

(d) eluting the adenoviral vector particle composition from the SEC column, and

(e) collecting a portion ofthe eluted composition to obtain a purified adenoviral vector particle composition.

186. The method of claim 185, wherein rate the SEC resin is packed onto the column is at least about 70 cm/hr.

187. The method of claim 186, wherein the rate the SEC column is packed into the column is about 90-200 cm/hr.

188. The method of any of claims 185-187, wherein the SEC resin is able to resolve proteins having masses of between 60-2000 kDa.

189. The method of any of claims 185-188, wherein the adenoviral vector particle composition is loaded, eluted, or both in a composition comprising at least about 400 mM of a monovalent salt.

190. The method of claim 189, wherein the adenoviral vector particle composition is loaded, eluted, or both in a composition comprising at least about 500-1200 mM of a monovalent salt.

191. The method of claim 189, wherein the adenoviral vector particle composition is loaded, eluted, or both in a composition comprising about 1000 mM of a monovalent salt.

192. The method of any of claims 185-188, wherein the adenoviral vector particle composition is loaded, eluted, or both in a composition comprising about 250-600 mM of a divalent salt.

193. The method of any of claims 185-192, wherein the adenoviral vector composition is loaded onto the packed SEC column in an amount of about 4%-15% ofthe total SEC column volume.

194. The method of any of claims 185-193, wherein the adenoviral vector particle composition is loaded onto the packed SEC column at a rate of about 20 cm/hr or more.

195. The method of claim 194, wherein the adenoviral vector particle composition is loaded onto the packed SEC column at a rate of about 60-80 cm/hr.

196. A method for preparing a purified adenoviral vector particle composition comprising;

(a) obtaining an adenoviral vector particle composition comprising a population of adenoviral vector particles and an undesired biomolecule,

(b) loading the adenoviral vector particle composition onto a column comprising an anion exchange chromatography (AEC) resin at a flow rate of at least about 300 cm/hr, wherein the method is performed without the use of cesium chloride density gradient centrifugation.

197. The method of claim 196, wherein the flow rate is at least about 400 cm/hr.

198. The method of claim 197, wherein the flow rate is at least about 500 cm/hr.

199. The method of any of claims 196-198, wherein the method further comprises;

(a) eluting the adenoviral vector particle composition from the column comprising an AEC resin,

(b) loading the eluted adenoviral vector particle composition onto a column comprising a size-exclusion chromatography (SEC) resin at a flow rate of about 50-120 cm/hr,

(c) eluting the adenoviral vector particle composition from the column comprising a SEC resin, and

(d) collecting a portion of the eluted adenoviral vector particle composition to obtain a purified adenoviral vector particle composition.

200. The method of claim 199, wherein the flow rate is about 60-80 cm/hr.

201. A method for preparing a purified adenoviral vector particle composition comprising;

(a) obtaining an adenoviral vector particle composition comprising a population of adenoviral vector particles and an undesired biomolecule,

(b) loading the adenoviral vector particle composition onto a liquid chromatography column,

(c) eluting the adenoviral vector particle composition from the column,

(d) loading the adenoviral vector particle composition onto a column in a first direction,

(e) eluting the adenoviral vector particle composition from the column in the direction opposite ofthe first direction, and

(f) collecting a portion of the eluted adenoviral vector particle composition to obtain a purified adenoviral vector particle composition.

202. The method of claim 201 , wherein the column(s) comprise an ion exchange chromatography (IEC) resin.

203. The method of claim 202, wherein the IEC resin is functionalized with a tertiary amine binding moiety having at least three carbon atoms, a quaternary amine binding moiety, or both, wherein the IEC binding moiety is more selective for adenovirus than a DEAE binding moiety.

204. The method of claim 203 , wherein the tertiary amine binding moiety is a dimethylaminopropyl moiety, dimethylaminobutyl moiety, dimethylaminoisobutyl moiety, or dimethylaminopentyl moiety.

205. The method of any of claims 201 -204, wherein the adenoviral vector particle composition is loaded onto the column at a rate of about 250-550 cm hr.

206. The method of any of claims 201-205, wherein the population of adenoviral vector particle composition is eluted from the column(s) by adding a composition comprising about 400-600 mM NaCl to the column in an amount sufficient to elute a majority ofthe adenoviral vector particles from the column(s).

207. The method of any of claims 201-206, wherein the volume of the purified adenoviral vector particle composition that is eluted from the column in step (e) is at least about 15% less than the volume of a purified adenoviral vector particle composition eluted from a HPLC column when the adenoviral vector particle composition is eluted in the same direction as it is loaded onto the column.

208. The method of claim 207, wherein the volume of the purified adenoviral vector particle composition that is eluted from the column in step (e) is at least about 50% less than the volume of a purified adenoviral vector particle composition eluted from a column when the adenoviral vector particle composition is eluted in the same direction as it is loaded onto the column

209. The method of claim 201 , wherein the chromatography columns are liquid chromatrography columns.

210. The method of claim 209, wherein the liquid chromatography columns are high performance liquid chromatography columns.

211. The method of any of claims 201 -210, wherein the volume of the purified adenoviral vector particle composition collected in step (f) is smaller than if the adenoviral vector particle composition was eluted in step (e) in the same direction as the first direction.

212. A method for eluting at least a portion of an adenoviral vector particle composition from a chromatography column comprising;

(a) subjecting a composition comprising a population of adenoviral vectors to an ion exchange chromatography resin such that a population of adenoviral vector particles binds to the resin, and

(b) eluting at least a portion ofthe composition from the column in a step wise fashion by sequentially subjecting the column to a number of elution buffers wherein each preceding buffer has a lower salt concentration than the succeeding buffer immediately following and the buffers are not blended prior to being subjected to the column, the portion ofthe composition comprising a population of adenoviral vector particles.

213. The method of claim 212, wherein there are five elution buffers which each buffer comprising a monovalent salt having a concentration of about 250 mM-1.5 M.

214. The method of claim 213, wherein the first elution buffer subjected to the column comprises a monovalent salt having a concentration of about 300 mM.

215. The method of claim 213, wherein the final elution buffer subjected to the column comprises a monovalent salt having a concentration of about 1 M.

216. The method of any of claims 212-215, wherein the process of switching from one buffer to the next is under the control of an automated programmable control system.

217. The method of claim 216, wherein the automated programmable control system monitors the pH, conductivity, or both, of each elution buffer such that a predetermined pH level, conductivity level, or both is maintained during elution ofthe portion ofthe composition.

218. The method of claim 216 or claim 217, wherein the automated programmable control system controls the collection fractions comprising the adenoviral vector particles.

219. The method of any of claims 212-218, wherein the ion exchange chromatography resin is an anion exchange chromatography resin.

220. The method of claim 218, wherein the anion exchange chromatography resin comprises a binding moiety functionalized with a tertiary amine or quaternary amine binding moiety that is more selective for adenoviral vector particles than DEAE.

221. A method for preparing a purified adenoviral vector particle composition comprising;

(a) obtaining an adenoviral vector particle composition comprising a population of adenoviral vector particles and an undesired biomolecule,

(b) providing a first column comprising an ion exchange chromatography (IEC) resin and providing at least one additional column comprising an IEC resin, wherein the first and the at least one additional columns are connected in series,

(c) loading the adenoviral vector particle composition onto the first column in an amount greater than the capacity ofthe first column such that the first column becomes saturated and creates an overflow ofthe adenoviral vector particle composition, which overflow directly runs into the at least one additional column(s), (d) independently eluting each column, and

(e) collecting a portion of each eluted composition to obtain one or more purified adenoviral vector particle compositions.

222. The method of claim 221 , wherein the adenoviral vector particle composition is loaded onto the first column in step (c) in a first direction and is eluted from the first column in step (d) in a direction opposite ofthe first direction.

223. The method of claim 221 or claim 222, wherein the at least one additional column consists of one column comprising an IEC resin connected in series to the first column.

224. The method of claim 223, wherein eluted composition from the first column is collected and loaded onto a column comprising an SEC resin.

225. The method of claim 224, wherein the composition is run through the SEC column and a portion ofthe composition is collected to obtain a purified adenoviral vector particle composition.

226. The method of claim 225, wherein the method further comprises at least one filtration step.

227. The method of claim 223, wherein the eluted composition from the at least one additional column is collected and loaded onto a column comprising an SEC resin.

228. The method of claim 225, wherein the method further comprises at least one filtration step.

229. A method for preparing a purified adenoviral vector particle composition comprising;

(a) obtaining an adenoviral vector particle composition comprising a population of adenoviral vector particles and an undesired biomolecule,

(b) loading the adenoviral vector particle composition onto a column comprising (1) a silica-based charged membrane, (2) a hydrophobic interaction chromatography (HIC) resin, (3) an ion exchange chromatography (IEC) resin, or (4) any combination of (l)-(3),

(c) eluting the adenoviral vector particle composition from the column comprising (1), (2), (3) or (4),

(d) loading the eluted adenoviral vector particle composition onto a column comprising an anion exchange chromatography (AEC) resin functionalized with a tertiary amine binding moiety comprising at least three carbon atoms, a quaternary amine binding moiety, or both, wherein the AEC binding moiety is more selective for adenoviral vector particles than a DEAE binding moiety,

(e) eluting the adenoviral vector particle composition from the column comprising an AEC resin,

(f) loading the eluted composition onto a column comprising a size- exclusion chromatography (SEC) resin,

(g) eluting the adenoviral vector particle composition from the column comprising a SEC resin, and

(h) collecting a portion ofthe eluted adenoviral vector particle composition to obtain a purified adenoviral vector particle composition.

230. The method of claim 229, wherein the tertiary amine binding moiety is a dimethylaminopropyl moiety, dimethylaminobutyl moiety, dimethylaminoisobutyl moiety, or dimethylaminopentyl moiety.

231. The method of claim 229 or claim 230, wherein the method further comprises subjecting the composition in step (d) to an endonuclease.

232. The method of claim 231 , wherein the method further comprises, after step (h), subjecting the adenoviral vector particle composition to at least one filtration step.

233. The method of any of claims 229-232, wherein, in step (b), the adenoviral vector particle composition is loaded onto a column comprising a HIC resin, and, in step (d), the adenoviral vector particle composition is subjected to the AEC resin without first performing tangential flow filtration on the composition, diluting the composition, or desalting the composition.

234. The method of any of claims 229-233, wherein the HIC resin comprises a non-porous hydrophobic interaction chromatography resin.

235. The method of any of claims 229-234, wherein the IEC resin is an anion exchange chromatography resin.

236. A method for preparing a purified adenoviral vector particle composition comprising;

(a) obtaining an adenoviral vector particle composition comprising a population of adenoviral vector particles and an undesired biomolecule,

(b) loading the adenoviral vector particle composition onto a column comprising a negative chromatography (NC) resin,

(c) collecting the adenoviral vector particle composition which does not bind to the NC resin,

(d) loading the collected adenoviral vector particle composition onto a column comprising an anion exchange chromatography (AEC) resin functionalized with a tertiary amine binding moiety comprising at least three carbon atoms, a quaternary amine binding moiety, or both, wherein the AEC binding moiety is more selective for adenoviral vector particles than a DEAE binding moiety,

(e) eluting the adenoviral vector particle composition from the column comprising an AEC resin,

(f) loading the eluted adenoviral vector particle composition onto a column comprising a size-exclusion chromatography (SEC) resin,

(g) eluting the adenoviral vector particle composition from the column comprising the SEC resin, and

(h) collecting a portion ofthe eluted adenoviral vector particle composition to obtain a purified adenoviral vector particle composition.

237. The method of claim 236, wherein the NC resin is a hydrophobic interaction chromatography (HIC) resin.

238. The method of claim 236 or claim 237, wherein the NC resin is responsible for removing DNA impurities from the adenoviral vector composition.

239. The method of any of claims 236-238, wherein the NC resin is responsible for removing protein impurities from the adenoviral vector composition.

240. The method of any of claims 236-238, wherein the NC resin is responsible for removing lipid impurities from the adenoviral vector composition.

241. A method of producing a viral vector particle composition, the method comprising:

(a) culturing a population of viral vector packaging cells in a medium within a closed bioreactor,

(b) infecting the cells with a viral vector particle and propagating the cells such that a population of viral vector particle infected cells is obtained,

(c) harvesting the viral vector particle infected cells by transferring at least a portion ofthe medium comprising the viral vector infected cells to a closed harvesting container through a harvest transfer closed passageway,

(d) lysing the viral vector particle infected cells in the harvesting container, or transferring the cells by a microfluidizer closed passageway to a closed microfluidizer which lyses the cells, to obtain an viral vector particle composition,

(e) transferring the viral vector particle composition to a closed filter system by a filter transfer closed passageway and filtering the viral vector particle composition to obtain a filtered viral vector particle composition, and

(f) transferring the viral vector particle composition to a closed chromatography column system by way of a chromatography transfer closed passageway, subjecting the filtered viral vector particle composition to chromatography column, and eluting a purified viral vector particle composition from the chromatography column, wherein at no point during or between steps (c) and (f) ofthe method are the viral vector particles or viral vector particle infected cells exposed to the environment.

242. The method of claim 241 , wherein the harvesting container comprises a sterile plastic bag.

243. The method of claims 241 -242, wherein viral vector particles are non- enveloped viral vector particles and the method comprises maintaining the non-enveloped viral vector particles or viral vector infected cells within a container in a liquid composition comprising about 1-25% trehalose for aperiod of at least about 3 hours, between steps (c) and (d) ofthe method, between (e) and (f) ofthe method, or both, wherein at least about 70% ofthe non-enveloped viral vector particles remain active at the end ofthe period.

244. The method of any of claims 242-243, wherein the non-enveloped viral vector particles are maintained in the liquid composition between steps (e) and (f) ofthe method, wherein the container consist essentially of a sterile plastic bag comprising a connector fitted to the closed filter, a connector fitted to the chromatography column, or both.

245. The method of any of claims 241 -244, wherein the harvest fransfer closed passageway, microfluidizer closed passageway, filter fransfer closed passageway, chromatography transfer closed passageway, or combination thereof comprises a sterile C- flex connector, a steam sterilized steam block connector, or combination thereof.

246. The method of claim 245, wherein the harvest fransfer closed passageway, microfluidizer closed passageway, filter transfer closed passageway, and chromatography transfer closed passageway comprise a steam sterilized steam block connector.

247. The method of any of claims 241 -246, wherein the closed filtration system comprises at least one tangential flow filfration.

248. The method of any of claims 241 -247, wherein the method comprises subjecting the viral vector particle composition to benzon nuclease digestion in the closed filtration system.

249. The method of claim 248, wherein the benzon nuclease digestion is performed at about 35° C.

250. The method of claim 249, wherein the benzon nuclease digestion reduces the amount of non-viral-encapsidated DNA in the closed filtration system by at least two logs.

251. A method of producing a non-enveloped viral vector particle composition comprising:

(a) lysing non-enveloped viral vector particle-infected cells to obtain a lysate,

(b) purifying the lysate by filfration to obtain a filtered lysate,

(c) subjecting the filtered lysate to chromatography with at least one ion exchange chromatography column, at least one size-exclusion chromatography column, or a combination thereof to obtain a purified viral vector particle composition, and

(d) placing the purified viral vector particle composition in a storage composition to obtain a non-enveloped viral vector particle composition, wherein the lysate, filtered lysate, and/or purified viral vector particle composition is maintained in a storage composition comprising about 1-25% (wt./vol.) trehalose, 0.001-0.015%) polysorbate 80, 10-65mM arginine, or a combination thereof for a period of at least about three hours between steps (a) and (d) ofthe method such that at least about 70% ofthe viral vectors in the lysate, filtered lysate, and/or purified stock are active at the end ofthe period.

252. The method of claim 251 , wherein at least about 80% of the viral vectors the lysate, filtered lysate, and/or purified viral vector particle composition are active at the end ofthe period.

253. The method of any of claims 251 -252, wherein at least about 90% of the viral vectors the lysate, filtered lysate, and/or purified viral vector particle composition are active at the end ofthe period.

254. The method of any of claims 251-253, wherein the step of maintaining the lysate, filtered lysate, and/or purified stock is performed at between about 0° C and 50° C.

255. The method of any of claims 251-254, wherein the step of maintaining the lysate, filtered lysate, and/or purified stock is performed at between about 0-10° C.

256. The method of any of claims 251-255, wherein the storage composition contains about 5% trehalose.

257. A method of producing a viral vector particle composition, comprising:

(a) providing a population of viral vector particle infected cells,

(b) harvesting at least some ofthe infected cells to obtain a harvested cell composition,

(c) lysing the cells ofthe harvested cell composition to obtain a lysate,

(d) enriching the lysate for viral vector particles by filfration comprising contacting the lysate with a tangential flow filtration system to obtain a filtered lysate, and

(e) subjecting the filtered lysate to chromatography purification with a chromatography system comprising at least one ion exchange chromatography column, at least one size-exclusion chromatography column, or at least one of each, to obtain a purified viral vector particle composition, wherein the method comprises maintaining the harvested cell composition, filtered lysate, or both in a storage composition, at a temperature below 10° C, for a period of at least about 3 hours while at least about 70% ofthe viral vector particles remain active while assessing the operability ofthe tangential flow filtration system, the operability ofthe chromatography system, or both.

258. The method of claim 257, wherein the harvested cell composition, filtered lysate, or both are maintained in a storage composition at a temperature below about -35° C.

259. The method of any of claims 257-258, wherein the harvested cell composition, filtered lysate, or both are maintained in a storage composition at a temperature below about -50° C.

260. The method of any of claims 257-259, wherein the storage composition comprises about 1-25% (wt./vol.) trehalose, 0.001-0.015% polysorbate 80, 10-65mM arginine, or a combination thereof.

261. The method of any of claims 257-260, wherein assessing the operability tangential flow filtration system, the operability ofthe chromatography system, or both comprises calibration ofthe pH monitor, calibration ofthe conductivity monitors, performing an automated system check of system pressure and temperature monitors, performing an automated check ofthe system pumps for flow and diaphragm integrity, performing preventative maintenance, checking part replacement logs to ensure compliance with system operating instructions, or any combination thereof.

262. The method of any of claims 257-261, wherein the storage composition comprises about 5% trehalose.

263. A method of producing a viral vector particle composition, comprising:

(a) providing a population of viral vector particle infected cells,

(b) harvesting at least some ofthe infected cells to obtain a harvested cell composition,

(c) lysing the cells ofthe harvested cell composition to obtain a lysate, (d) enriching the lysate for viral vector particles by filtration comprising contacting the lysate with a tangential flow filfration system to obtain a filtered lysate, and

(e) subjecting the filtered lysate to chromatography purification with a chromatography system comprising at least one ion exchange chromatography column, at least one size-exclusion chromatography column, or at least one of each, to obtain a purified viral vector particle composition, and

(f) placing the purified viral vector particle composition in a storage composition to obtain a non-enveloped viral vector particle composition, wherein the method comprises maintaining the harvested cell composition, filtered lysate, or both in a storage composition, at a temperature below 10° C, for a period of at least about 3 hours while at least about 70% ofthe viral vector particles remain active while the harvested cell composition, filtered lysate, or both particle composition is assessed for host cell protein concentration, non- viral encapsidated DNA concentration, number of viral particles, number of infectious viral particles, the presence of adventitious vectors, or a combination thereof.

264. The method of claim 262, wherein the harvested cell composition, filtered lysate, or both are maintained in a storage composition at a temperature below about -35° C.

265. The method of claim 262 or claim 263, wherein the harvested cell composition, filtered lysate, or both are maintained in a storage composition at a temperature below about -50° C.

266. The method of any of claims 262-264, wherein the storage composition comprises about 1-25% (wt./vol.) trehalose, 0.001-0.015% polysorbate 80, 10-65mM arginine, or a combination thereof

267. The method of any of claims 262-265, wherein the storage composition comprises about 5% trehalose.

268. The method of any of claims 262-266, wherein the results ofthe assessment ofthe host cell protein concentration, non- viral encapsidated DNA concentration, number of viral particles, number of infectious viral particles, the presence of adventitious vectors, or a combination thereof determine whether the adenoviral vector composition is compared to predetermined standards of purity.

269. The method of claim 268, wherein the failure ofthe results ofthe assessment to meet or exceed the predetermined standards of purity results in discarding ofthe harvested cell composition, filtered lysate, or purified viral vector particle composition.

270. A system for efficiently producing purified adenoviral vector particle compositions comprising:

(a) lysing a population of adenoviral vector infected cells to form a lysate,

(b) transferring the lysate by way of a first closed connection to a filtration system,

(c) filtering the lysate with the filtration system to form a filtered composition,

(d) transferring the filtered composition by way of a second closed connection to a chromatography purification system,

(e) separating the components ofthe filtered composition by chromatography,

(f) obtaining a portion ofthe filtered composition comprising a population of adenoviral vector particles from a chromatography system comprising one or more chromatography columns to produce an adenoviral vector particle composition,

(g) decontaminating and cleaning the first closed connection, filfration system, second closed connection, chromatography system, or any combination thereof, and

(h) repeating steps (a)-(f) using the same first closed connection, filtration system, second closed connection, and chromatography system but a different population of adenoviral vector infected cells.

271. The method of claim 270, wherein decontamination of at least the first closed connection and second closed connection is performed by way of steam sterilization.

272. The method of claim 270 or claim 271, wherein decontamination ofthe filtration system, chromatography system, or both comprises subjecting the filtration system, chromatography system, or both to a decontamination solution having a pH of at least about 10.

273. The method of claim 272, wherein the decontamination solution has a pH of at least about 11 and at least about 0.1 M NaCl.

274. The method of claim 271 , wherein the decontamination of the filfration system, chromatography system or both comprises subjecting the filfration system, chromatography system, or both to a decontamination solution having a pH of about 3 or less.

275. The method of claim 274, wherein the decontamination solution has a pH of about 2 or less and at least about 0.1 M NaCl.

276. The method of claim 274, wherein the decontamination solution comprises acetic acid, phosphoric acid, citric acid, or a combination thereof.

277. The method of claim 272, wherein the decontamination solution comprises NaOH.

278. The method of claim 270, wherein the chromatography system comprises at least two chromatography column columns, wherein the at least two chromatography columns comprise different chromatography resins.

279. The method of claim 278, wherein the at least two chromatography resins comprise an anion exchange chromatography resin and a size-exclusion chromatography resin.

280. A method of preparing a purified adenoviral vector particle composition comprising:

(a) applying an adenoviral vector composition comprising a population of adenoviral vector particles to a filfration system comprising an automated monitor which is operably linked to automatic temperature and pH control mechanisms,

(b) monitoring the temperature and volume ofthe adenoviral vector composition in the filtration system such that if the volume, temperature, or both in the filfration system are outside of a pre-selected range, the monitor causes the temperature control mechanism, volume control mechanism, or both to change the volume, temperature, or both, such that the volume and temperature in the filtration system are maintained within the pre-selected range,

(c) filtering the adenoviral vector composition with the filfration system to obtain a filtered composition,

(d) applying the filtered composition to an anion exchange chromatography system comprising an automated monitor which is operably linked to automatic temperature and pH control mechanisms,

(e) monitoring the conductivity and pH of the adenoviral vector composition in the chromatography system such that if conductivity, pH, or both in the chromatography system are outside of a pre-selected range, the monitor causes the conductivity control mechanism, pH control mechanism, or both to change the pH, conductivity, or both, such that the pH and conductivity in the chromatography system are maintained within the pre-selected range, and

(f) eluting a portion ofthe filtered composition comprising a population of adenoviral vector particles from the chromatography resin to obtain a purified adenoviral vector particle composition.

281. The method of claim 280, wherein the filfration system automated monitor, chromatography system automated monitor, or both, further monitor and control the adjustment of pressure, conductivity, flow rate, volume, or any combination thereof.

282. The method of claim 280 or claim 281 , wherein the chromatography system monitor further automatically monitors UV absorbance of material eluting from the chromatography system, wherein the chromatography system automatically and selectively collects a portion ofthe filtered composition having a UV absorbance indicative of a population of adenoviral vector particles.

283. The method of claim 282, wherein the chromatography system monitor automatically monitors the level of UN absorbance ofthe chromatography system and instigates an automated flow control to reverse the direction of flow through the system, such that the portion ofthe filtered composition eluted from the chromatography system is eluted in the opposite direction ofthe direction the filtered composition was applied to the chromatography system.

284. The method of claim 282 or claim 283, wherein the method comprises monitoring the UN absorbance during purification ofthe adenoviral vector particle composition using at least two chromatography columns in series, the chromatography columns being linked to one or more automated monitors that instigate an automated flow control to reverse the direction of flow through the chromatography columns, such that the portion ofthe filtered composition eluted from each chromatography column is eluted in the opposite direction ofthe direction the filtered composition was applied to the chromatography columns.

285. The method of any of claims 281-284, wherein the method further comprises subjecting the purified adenoviral vector particle composition to a size-exclusion chromatography system which comprises a monitor that monitors pH, conductivity, or both, and pH and conductivity control mechanisms which adjust the pH, conductivity, or both, when the pH, conductivity, or both are outside of a pre-selected range, such that the pH and conductivity in the size-exclusion chromatography system are maintained within the preselected range.

286. A composition comprising at least about I x lO¹³ adenoviral vector particles and about lOng or less of non- viral encapsidated DNA per at least about I x lO⁵ cells.

287. The composition of claim 286, wherein the composition comprises about 10 ng of less of non- viral encapsidated DNA per at least about I x lO⁷ cells.

288. The composition of claim 286 or claim 287, wherein the composition comprises about 10 ng of less of non- viral encapsidated DNA per at least about 1 x I cells.

289. The composition of any of claims 286-288, wherein the composition comprises about 10 ng of less of non- viral encapsidated DNA per at least about 1 x 10 11 cells.

290. The composition of any of claims 286-289, wherein the adenoviral vector particles are replication-deficient adenoviral vector particles and the composition has a replication competent adenovirus (RCA) particle/total adenoviral vector particle ratio of less than about 1/1 x 10⁷.

291. The composition of any of claims 286-290, wherein the composition has a particle unit/focus forming unit (PU/FFU) ratio of about 30 or less.

292. The method of any of claims 286-291 , wherein the composition has a particle unit/focus forming unit (PU/FFU) ratio of about 20 or less.

293. The composition of any of claims 286-292, wherein at least about 75% ofthe adenoviral vector particles are active.

294. The composition of any of claims 286-293, wherein the composition comprises about 50 ng or less host cell protein.

295. The composition of any of claims 286-294, wherein host cell protein makes up about 0.5% or less ofthe total protein content ofthe composition.

296. The composition of any of claims 286-295, wherein less than about 10% of the adenoviral vector particles in the composition are empty capsids.

297. The composition of any of claims 286-296, wherein the replication-deficient adenoviral particles are El -deficient adenoviral vector particles and the composition has an El-revertant adenoviral vector particle to total adenoviral vector particle ratio of less than about 1/1 x 10⁶.

298. The composition of any of claims 286-297, wherein the adenoviral vector particles comprise a transgene, such that upon infection of culture comprising a population of cells with the composition at an MOI of at least about 5 and after a suitable period of time for transgene expression to occur the level of transgene product in the culture is at least about 40 fg/cell.

299. A composition comprising at least about I x lO¹² adenoviral vector particles and about 1 ng or less of non- viral encapsidated DNA per at least about I x lO⁵ cells.

300. The composition of claim 299, wherein about 1 ng or less of non- viral encapsidated DNA per at least about I x lO⁷ cells.

301. The composition of claim 299 or claim 300, wherein about 1 ng or less of non- viral encapsidated DNA per at least about I x lO⁹ cells.

302. The composition of any of claims 299-301, wherein about 1 ng or less of non- viral encapsidated DNA per at least about I x lO¹¹ cells.

303. The composition of any of claims 299-302, wherein the adenoviral vector particles are replication-deficient adenoviral vector particles and the composition has a RCA particle/total adenoviral vector particle ratio of less than about 1/1 x 10⁷.

304. The composition of any of claims 299-303, wherein the composition has a PU/FFU ratio of about 30 or less.

305. The composition of any of claims 299-304, wherein the composition has a PU/FFU ratio of about 20 or less.

306. The composition of any of claims 299-305, wherein at least about 75% ofthe adenoviral vector particles are active.

307. The composition of any of claims 299-306, wherein the composition comprises about 50 ng or less host cell protein.

308. The composition of any of claims 299-307, wherein host cell protein makes up about 0.5% or less ofthe total protein content ofthe composition.

309. The composition of any of claims 299-308, wherein less than about 10% of the adenoviral vector particles in the composition are empty capsids.

310. The composition of any of claims 299-309, wherein the replication-deficient adenoviral particles are El -deficient adenoviral vector particles and the composition has an El-revertant adenoviral vector particle to total adenoviral vector particle ratio of less than about 1/1 x 10⁶.

311. The composition of any of claims 299-310, wherein the adenoviral vector particles comprise a transgene, such that upon infection of culture comprising a population of cells with the composition at an MOI of at least about 5 and after a suitable period of time for transgene expression to occur the level of fransgene product in the culture is at least about 40 fg/cell.

312. A composition comprising at least about I x lO⁵ adenoviral vector particles and about 10 ng or less of non- viral encapsidated DNA of about 750 base pairs or more in length per at least about I x lO⁵ adenoviral vector particles.

313. The composition of claim 312, wherein the composition comprises about 10 ng or less of non- viral encapsidated DNA of about 410 base pairs or more in length per at least about 1 x 10⁵ adenoviral vector particles.

314. The composition of claim 312 or claim 313, wherein the composition comprises about 10 ng or less of non- viral encapsidated DNA of about 120 base pairs or more in length per at least about I x lO⁵ adenoviral vector particles.

315. The composition of any of claims 312-314, wherein the composition comprises at least about 1 x 10 adenoviral vector particles.

316. The composition of any of claims 312-315, wherein the composition comprises at least about I x lO⁹ adenoviral vector particles.

317. The composition of any of claims 312-316, wherein the adenoviral vector particles are replication-deficient adenoviral vector particles and the composition has an RCA total adenoviral vector particle ration of less than about 1/1 x 10⁷.

318. The composition of any of claims 312-317, wherein the composition has a PU/FFU ratio of about 20 or less.

319. The composition of any of claims 312-318, wherein at least about 80% ofthe adenoviral vector particles are active.

320. The composition of any of claims 312-319, wherein the composition comprises about 50 ng or less host cell protein per at least about I x lO⁵ adenoviral vector particles.

321. The composition of any of claims 312-320, wherein host cell protein makes up about 0.5% or less ofthe total protein content ofthe composition.

322. The composition of any of claims 312-321, wherein less than about 30% of the adenoviral vector particles in the composition are empty capsids.

323. The composition of any of claims 312-322, wherein less than about 10% of the adenoviral vector particles in the composition are empty capsids.

324. The composition of any of claims 312-323, wherein the adenoviral vector particles are El-deficient adenoviral vector particles and the composition has an El- revertant adenoviral vector particle to total adenoviral vector particle ratio of less than about 1/1 x 10⁶.

325. The composition of any of claims 312-324, wherein the adenoviral vector particles comprise a transgene, such that upon infection of culture comprising a population of cells with the composition at an MOI of at least about 5 and after a suitable period of time for fransgene expression to occur the level of fransgene product in the culture is at least about 40 fg/cell.

326. A composition comprising at least about 1 x 10⁵ adenoviral vector particles and about 50ng or less of host cell protein per at least about 1 x 10⁵ adenoviral vector particles.

327. The composition of claim 326, wherein the composition comprises about 50ng or less of host cell protein per at least about 1 x 10⁷ adenoviral vector particles.

328. The composition of claim 326 or claim 327, wherein the composition compri -ssees about 50ng or less of host cell protein per at least about I x lO⁹ adenoviral vector particles.

329. The composition of any of claims 326-328, wherein the composition comprises about 50ng or less of host cell protein per at least about 1 x lθ" adenoviral vector particles.

330. The composition of any of claims 326-329, wherein the composition contains about 40ng or less of host cell protein.

331. The composition of any of claims 326-330, wherein the composition contains about 30ng or less of host cell protein.

332. The composition of any of claims 326-331 , wherein the composition contains about 20ng or less of host cell protein.

333. The composition of any of claims 326-332, wherein the composition contains about lOng or less of host cell protein.

334. The composition of any of claims 326-333, wherein the composition comprises at least about I x lO⁷ adenoviral vector particles.

335. The composition of any of claims 326-334, wherein the adenoviral vector particles are replication-deficient adenoviral vector particles and the composition comprises less than about 1 replication-competent adenoviral vector particle in about 1 x 10 adenoviral vector particles.

336. The composition of any of claims 326-335, wherein the adenoviral vector particles are El -deficient adenoviral vector particles and the composition comprises less than about 1 El-revertant adenoviral vector particle in about I x lO⁶ adenoviral vector particles.

337. The composition of any of claims 326-336, wherein the composition has a PU/FFU ratio of about 20 or less.

338. The composition of any of claims 326-337, wherein at least about 80% ofthe adenoviral vector particles are active.

339. The composition of any of claims 326-338, wherein host cell protein makes up about 0.5% or less ofthe total protein content ofthe composition.

340. The composition of any of claims 326-339, wherein less than about 30% of the adenoviral vector particles in the composition are empty capsids.

341. The composition of any of claims 326-340, wherein the adenoviral vector particles comprise a transgene, such that upon infection of culture comprising a population of cells with the composition at an MOI of at least about 5 and after a suitable period of time for fransgene expression to occur the level of fransgene product in the culture is at least about 40 fg/cell.

342. The composition of any of claims 326-341, wherein the composition comprises about 10 ng or less of non-viral-encapsidated DNA.

343. The composition of any of claims 326-342, wherein the composition comprises about 10 ng or less of non-viral-encapsidated DNA of about 750 base pairs or more in length.

344. A composition comprising at least about I x lO⁵ adenoviral vector particles wherein the composition contains about 20ng or less of protein fragments having an apparent molecular weight of about 70 kDa.

345. The composition of claim 344, wherein the composition contains about 15 ng or less of host cell protein having an apparent molecular weight of about 70 kDa.

346. The composition of claim 344 or claim 345, wherein the composition contains about 10 ng or less of protein fragments having an apparent molecular weight of about 70 kDa.

347. The composition of any of claims 344-346, wherein the composition contains about 5 ng or less of protein fragments having an apparent molecular weight of about 70 kDa.

348. The composition of any of claims 344-347, wherein the composition comprises at least about I x lO⁷ adenoviral vector particles.

349. The composition of any of claims 344-348, wherein the composition has a PU/FFU ratio of about 20 or less.

350. The composition of any of claims 344-349, wherein at least about 80% ofthe adenoviral vector particles are active.

351. The composition of any of claims 344-350, wherein host cell protein makes up about 0.5% or less ofthe total protein content ofthe composition.

352. The composition of any of claims 344-351, wherein less than about 30% of the adenoviral vector particles in the composition are empty capsids.

353. The composition of any of claims 344-352, wherein the adenoviral vector particles are El-deficient adenoviral vector particles and the composition has an El- revertant adenoviral vector particle to total adenoviral vector particle ratio of less than about 1/1 x 10⁶.

354. The composition of any of claims 344-353, wherein the adenoviral vector particles are replication-deficient adenoviral vector particles and the composition has an RCA particle/total adenoviral vector particle ratio of less than about 1/1 x 10 .

355. The composition of any of claims 344-354, wherein the adenoviral vector particles comprise a transgene, such that upon infection of culture comprising a population of cells with the composition at an MOI of at least about 5 and after a suitable period of time for transgene expression to occur the level of transgene product in the culture is at least about 40 fg/cell.

356. A composition comprising at least about I x lO⁵ adenoviral vector particles wherein the composition contains a PU/FFU ratio of about 30 or less.

357. The composition of claim 356, wherein the composition has a PU/FFU ratio ofabout 20 or less.

358. The composition of claim 356 or claim 357, wherein the composition comprises at least about I x lO⁷ adenoviral vector particles.

359. The composition of any of claims 356-358, wherein the PU/FFU ratio is about 20 or less.

360. The composition of any of claims 356-359, wherein the PU/FFU ratio is about 10 or less.

361. The composition of any of claims 356-360, wherein the PU/FFU ratio is about 5 or less.

362. A composition comprising at least about I x lO⁵ adenoviral vector particles wherein the composition contains less than about 30% empty viral capsids.

363. The composition of claim 362, wherein the composition contains less than about 20% empty viral capsids.

364. The composition of claim 362 or claim 363, wherein the composition contains less than about 10% empty viral capsids.

365. The composition of any of claims 362-364, wherein the composition contains less than about 5% empty viral capsids.

366. A composition comprising at least about I x lO⁵ adenoviral vector particles wherein host cell protein makes up about 0.5% or less ofthe total protein content ofthe composition.

367. The composition of claim 366, wherein host cell protein makes up about 0.25% or less ofthe total protein content ofthe composition.

368. The composition of claim 366 or claim 367, wherein the amount of protein having an apparent molecular weight of about 70 kDa is about 0.25% or less ofthe total protein content ofthe composition.

369. A composition comprising at least about 1 x 10⁵ recombinant replication- deficient adenoviral vector particles comprising a fransgene that is expressed to produce a transgene product, wherein the composition when contacted with a population of cells at an MOI of at least about 5 results in expression of at least about 40 fg fransgene product per cell.

370. The composition of claim 369, wherein contacting the composition with a population of cells at an MOI of at least about 5 results in expression of at least about 75 fg transgene product per cell.

371. A method for obtaining a purified stock of adenoviral vector particles comprising:

(a) subjecting an adenoviral vector particle composition to benzonase digestion at about 34-36° C for at least about 4 hours to obtain a reduced DNA level composition,

(b) subjecting the reduced DNA level composition to tangential flow filtration to obtain a filtered composition,

(c) subjecting the filtered composition to ion exchange chromatography purification using an ion exchange chromatography resin comprising a binding moiety more selective for adenovirus particles than DEAE to obtain an IEC purified composition, and

(d) subjecting the purified composition to size-exclusion chromatography to obtain a purified adenoviral vector particle composition, wherein the method is performed without cesium chloride centrifugation and the purified adenoviral vector particle composition has about 10 ng or less of non- viral encapsidated DNA of about 750 base pairs or more in length per at least about I x lO⁵ adenoviral vector particles.

372. The method of claim 371, wherein the purified adenoviral vector composition has about 10 ng or less of non- viral encapsidated DNA of about 410 base pairs or more in length per at least about I x lO⁵ adenoviral vector particles.

373. The method of claim 371 or claim 372, wherein the purified adenoviral vector particle composition has about 10 ng or less of non- viral encapsidated DNA of about 120 base pairs or more in length per at least about I x lO⁵ adenoviral vector particles.

374. A method for obtaining a purified stock of adenoviral vector particles comprising:

(a) subjecting an adenoviral vector particle composition to benzonase digestion at about 34-36° C for at least about 4 hours to obtain a reduced DNA level composition,

(b) subjecting the reduced DNA level composition to tangential flow filfration to obtain a filtered composition,

(c) subjecting the filtered composition to ion exchange chromatography purification using an ion exchange chromatography resin comprising a binding moiety more selective for adenovirus particles than DEAE to obtain an IEC purified composition, and

(d) subjecting the purified composition to size-exclusion chromatography to obtain a purified adenoviral vector particle composition, wherein the method is performed without cesium chloride centrifugation and the purified adenoviral vector particle composition has a PU/FFU ratio of about 30 ng of non-viral encapsidated DNA of about 750 base pairs or more in length per at least about I x lO⁵ adenoviral vector particles.

375. The method of claim 374, wherein the purified adenoviral vector composition has about 30 ng or less of non-viral encapsidated DNA of about 410 base pairs or more in length.

376. The method of claim 374 or claim 375, wherein the purified adenoviral vector particle composition has about 30 ng or less of non-viral encapsidated DNA of about 120 base pairs or more in length.

377. A method of assessing the effectiveness of a purification technique used to prepare an adenoviral vector composition comprising subjecting the composition before and after the purification technique is applied to Western Blot analysis and evaluating whether the amount of protein having an apparent molecular weight of about 70kDa protein is reduced after performing the technique.

378. A method of assessing the purity of an adenoviral vector composition comprising subjecting the adenoviral vector composition to Western Blot analysis and evaluating the amount of protein having an apparent molecular weight of about 70kDa.

379. The method of claim 377 or claim 378, wherein the technique is repeated if the amount of protein having an apparent molecular weight of about 70kDa in the adenoviral vector particle composition is not reduced after performing the technique.

380. A method of preparing a polyclonal antibody composition that visually reacts with host cell proteins in an adenoviral vector particle composition in a Western Blot assay comprising:

(a) providing host cells,

(b) lysing the cells to obtain a lysate,

(c) preparing a composition comprising polyclonal antibodies to a majority ofthe proteins the lysate at a titer such that at least a majority ofthe host cell's proteins can be visualized on a Western Blot,

(d) subjecting the polyclonal antibodies to affinity column chromatography purification using at least a majority ofthe adenoviral vector particle's proteins to obtain a purified host cell protein polyclonal antibody composition to obtain a polyclonal antibody composition that visually reacts with host cell proteins in an adenoviral vector particle composition in a Western Blot assay.

381. A method of determining host cell protein contamination in an adenoviral vector particle composition comprising subjecting the adenoviral vector particle composition to Western Blot analysis using polyclonal antibodies prepared by the method of claim 380.

382. A purified adenoviral vector particle composition derived from a lysate of adenoviral vector particle host cells, the purified composition exhibiting a reduction of host cell DNA by a factor of at least about 3 logs as compared to the amount of host cell DNA in the unpurified lysate.

383. The composition of claim 382, wherein the purified composition exhibits a reduction of host cell protein by a factor of at least about 3 logs as compared to the amount of host cell protein in the unpurified lysate.

384. The composition of claim 382 or claim 383, wherein the composition exhibits a reduction of host cell DNA by a factor of at least about 5 logs as compared to the amount of host cell DNA in the unpurified lysate.

385. A method of assessing the effectiveness of a purification technique used to prepare an adenoviral vector composition comprising subjecting the composition before and after the purification technique is applied to enzyme immunoassay (EIA) analysis and evaluating whether the amount of protein having an apparent molecular weight of about 70kDa protein is reduced after performing the technique.

386. The method of claim 385, wherein the EIA is enzyme linked immunosorbant assay (ELISA).

387. A method of assessing the purity of an adenoviral vector composition comprising subjecting the adenoviral vector composition to EIA analysis and evaluating the amount of protein having an apparent molecular weight of about 70kDa.

388. The method of claim 387, wherein the EIA analysis is ELISA analysis.

389. The method of claim 385 or claim 386, wherein the technique is repeated if the amount of protein having an apparent molecular weight of about 70kDa in the adenoviral vector particle composition is not reduced after performing the technique.

390. A method of preparing a polyclonal antibody composition that visually reacts with host cell proteins in an adenoviral vector particle composition in an enzyme immunoassay (EIA) comprising:

(a) providing adenoviral vector infected host cells,

(b) lysing the cells to obtain a lysate,

(c) preparing a composition comprising polyclonal antibodies to a majority ofthe proteins ofthe lysate at a titer such that at least a majority ofthe host cell's proteins can be visualized by EIA,

(d) subjecting the polyclonal antibodies to affinity column chromatography purification using at least a majority ofthe adenoviral vector particle's proteins to obtain a purified host cell protein polyclonal antibody composition to obtain a polyclonal antibody composition that visually reacts with host cell proteins in an adenoviral vector particle composition in a EIA.

391. The method of claim 390, wherein the EIA is an enzyme linked immunosorbant assay (ELISA).