Novel adenovirus gene therapy vehicle and cell line

Abstract

A novel adenovirus E1/E4 expressing packaging cell line is provided, which permits the generation of recombinant adenoviruses deleted in both gene regions. The E1/E4 deleted recombinant adenovirus is capable of expressing a selected transgene product in cells in vivo or in vitro. This recombinant virus is useful in the treatment of genetic disorders.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation of U.S. patent application Ser. No. 09/650,594, filed Aug. 30, 2000, which is a continuation of U.S. patent application Ser. No. 08/549,489, filed Oct. 27, 1995, now U.S. Pat. No. 6,281,010, which is a continuation-in-part of U.S. patent application Ser. No. 08/462,014, filed Jun. 5, 1995, now U.S. Pat. No. 5,756,283. The disclosure of parent application Ser. No. 08/462,014 is incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0003] The present invention relates to the field of somatic gene therapy and the treatment of genetic disorders.

[0004] Adenoviruses are eukaryotic DNA viruses that can be modified to efficiently deliver a therapeutic or reporter transgene to a variety of cell types. Human adenoviruses are comprised of a linear, approximately 36 kb double-stranded DNA genome, which is divided into 100 map units (m.u.), each of which is 360 bp in length. The DNA contains short inverted terminal repeats (ITR) at each end of the genome that are required for viral DNA replication. The gene products are organized into early (E1 through E4) and late (L1 through L5) regions, based on expression before or after the initiation of viral DNA synthesis [see, e.g., M. S. Horwitz et al, "Adenoviridae and Their Replication", Virology, second edition, pp. 1712, ed. B. N. Fields et al, Raven Press Ltd., New York (1990)]. The adenoviruses types 2 and 5 (Ad2 and Ad5, respectively), are not associated with human malignancies.

[0005] Recombinant adenoviruses are capable of providing extremely high levels of transgene delivery to virtually all cell types, regardless of the mitotic state. The efficacy of this system in delivering a therapeutic transgene in vivo that complements a genetic imbalance has been demonstrated in animal models of various disorders [K. F. Kozarsky et al, Somatic Cell Mol. Genet., 19:449-458 (1993) ("Kozarsky et al I"); K. F. Kozarsky et al, J. Biol. Chem., 269:13695-13702 (1994) ("Kozarsky et al II); Y. Watanabe, Atherosclerosis, 36:261-268 (1986); K. Tanzawa et al, FEBS Letters, 118(1):81-84 (1980); J. L. Golasten et al, New Engl. J. Med., 309(11983) :288-296 (1983); S. Ishibashi et al, J. Clin. Invest., 92:883-893 (1993); and S. Ishibashi et al, J. Clin. Invest., 93:1885-1893 (1994)]. The use of recombinant adenoviruses in the transduction of genes into hepatocytes in vivo has previously been demonstrated in rodents and rabbits [see, e.g., Kozarsky II, cited above, and S. Ishibashi et al, J. Clin. Invest., 92:883-893 (1993)].

[0006] The first-generation recombinant, replication-deficient adenoviruses which have been developed for gene therapy contain deletions of the entire E1a and part of the E1b regions. This replication-defective virus is grown on an adenovirus-transformed, complementation human embryonic kidney cell line containing a functional adenovirus E1a gene which provides a transacting E1a protein, the 293 cell [ATCC CRL1573]. E1-deleted viruses are capable of replicating and producing infectious virus in the 293 cells, which provide E1a and E1b region gene products in trans. The resulting virus is capable of infecting many cell types and can express the introduced gene (providing it carries its own promoter), but cannot replicate in a cell that does not carry the El region DNA unless the cell is infected at a very high multiplicity of infection.

[0007] However, in vivo studies revealed transgene expression in these E1 deleted vectors was transient and invariably associated with the development of severe inflammation at the site of vector targeting [S. Ishibashi et al, J. Clin. Invest., 93:1885-1893 (1994); J. M. Wilson et al, Proc. Natl. Acad. Sci., USA, 85:4421- 4424 (1988); J. M. Wilson et al, Clin. Bio., 3:21-26 (1991); M. Grossman et al, Som. Cell. and Mol. Gen., 17:601-607 (1991)]. Antigenic targets for immune mediated clearance are viral proteins expressed from the recombinant viral genome and/or the product of the transgene [Y. Yang et al, Proc. Natl. Acad. Sci., USA, 91:4407-4411 (May 1994); Y. Yang et al, Immun., 1:433-442 (August 1994)].

[0008] There remains a need in the art for additional recombinant adenoviruses, therapeutic compositions and methods which enable effective treatment of disorders and diseases by gene therapy.

SUMMARY OF THE INVENTION

[0009] In one aspect of this invention, a novel packaging cell line is provided which expresses adenovirus genes E1a, E1b and E4, or functional fragments thereof. In one embodiment, the E4 gene fragment is open reading frame (ORF) 6 under the control of an inducible promoter.

[0010] In another aspect, the invention provides a recombinant adenovirus comprising the DNA of, or corresponding to, at least a portion of the genome of an adenovirus having functional deletions of the E1 and E4 gene regions; a suitable gene operatively linked to regulatory sequences directing its expression, and an adenovirus capsid, the recombinant virus capable of infecting a mammalian cell and expressing the gene product in the cell in vivo or in vitro. In a preferred embodiment, the cell is a muscle cell.

[0011] In another aspect, the invention provides a mammalian cell infected with the recombinant virus described above.

[0012] In still another aspect, the invention provides a recombinant adenovirus shuttle vector comprising the DNA of, or corresponding to, at least a portion of the genome of an adenovirus having functional deletions of the E1 and E4 gene regions; a suitable gene operatively linked to regulatory sequences capable of directing its expression; and plasmid sequences.

[0013] In still a further aspect, the invention provides a method for delivering and stably integrating a selected gene into a mammalian cell comprising introducing into said cell an effective amount of a recombinant virus described above.

[0014] In another aspect, the invention provides a method for producing the above-described recombinant Ad virus by co-transfecting the shuttle vector described above and a helper adenovirus into the packaging cell line described above, wherein the transfected cell generates the recombinant adenovirus. The recombinant adenovirus is subsequently isolated and purified therefrom.

[0015] Other aspects and advantages of the present invention are described further in the following detailed description of the preferred embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a schematic drawing of an exemplary plasmid useful for the construction of a packaging cell line of this invention. Plasmid pMMTVE4ORF6 or pMTE4ORF6, which contains a mouse mammary tumor virus promoter (MMTV promoter) or a sheep metallothionine promoter (MT promoter), respectively, in control of a human E4 ORF 6 gene sequence, a growth hormone gene terminator sequence (GH), an SV40 origin of replication, plasmid sequences from a pBR322-based plasmid including a neomycin resistance gene, an SV40 polyadenylation site and an ampicillin resistance gene.

[0017] FIGS. 2A through 2F provides the continuous DNA sequence [SEQ ID NO: 1] of the minigene containing the MMTV promoter in operative control of the adenovirus serotype 5 E4 gene open reading frame 6. Nucleotides 1-1506 provide the MMTV promoter. Nucleotides 1523-2408 span E4 ORF6 and the amino acid sequence of ORF 6 [SEQ ID NO: 2] is indicated under the ORF DNA sequence. Nucleotides 2409-3654 span the growth hormone gene (GH) terminator sequences, which provide the polyadenylation site.

[0018] FIG. 3 is a schematic map of recombinant adenovirus H5.001CBLacZ, with indicated restriction endonuclease enzyme sites. The striated bar represents the CBLacZ minigene; the black bar represents Ad5 viral backbone, the crosshatched bar represents Ad E4 deletion.

[0019] FIGS. 4A through 4CC provide the DNA sequence [SEQ ID NO: 3] of recombinant adenovirus H5.001CBLacZ in which nucleotides 1-330 span Ad map units 0-1; nucleotides 370-928 span the CMV enhancer/chicken .beta.-actin promoter (CB);nucleotides 945-4429 encode E. coli .beta.-galactosidase, nucleotides 4429-4628 span the polyadenylation sequence; and nucleotides 4671-35408 span Ad5 sequences m.u. 9.2 to about m.u. 92.1 and from about m.u. 97.3 to m.u. 100 (containing a substantial deletion of the E4 gene between m.u. 92 through 97.2).

[0020] FIG. 5 is a graph plotting LacZ forming units/ml vs time (hours) for E4 complementing cell lines infected with H5.001CBLacZ.

[0021] FIG. 6A is a graph of the induction, ORF6 expression and viral production in 293-27-18 packaging cells plotting yield at 24 hours post-infection in LacZ forming units (LFU)/ml and ORF6 protein (abs.mm) vs. concentration of the inducer, dexamethasone (.mu.M). The unit reference, abs.mm, indicates the intensity of the size of the protein band on a Western blot and reflects absorbence and protein size in mm.sup.2. The square represents the yield at 24 hours post infection. The diamond represents ORF6 protein detected at 24 hours post-infection.

[0022] FIG. 6B is a graph of the induction, ORF6 expression and viral production in 293-10-3 packaging cells plotting yield at 24 hours post-infection in LFU/ml and ORF6 protein (abs.mm) vs. concentration of the inducer, zinc (.mu.M). The symbols are as described for FIG. 6A.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention provides novel packaging cell lines, which enable the production of recombinant adenoviruses functionally deleted in both the E1 and E4 genes, and methods which enable the therapeutic treatment of disorders with such recombinant adenoviruses.

[0024] To increase the transgene capacity and decrease immune response of recombinant adenoviral vectors, as many viral genes as possible should be deleted to inactivate the adenovirus. However, it is crucial to generate complementing cell lines for construction and propagation of such deleted adenoviral vectors. The method and compositions of the present invention overcome several problems previously identified in the gene therapy for first generation E1 deleted adenoviruses and display advantages in administration particularly to muscle tissue.

I. Novel Packaging Cell Lines

[0025] Early region 4 (E4) of adenovirus serotype 5 consists of 7 open reading frames (ORFs) believed to be involved in viral DNA replication, host cell shut-off, and late mRNA accumulation. To generate recombinant adenoviruses (Ad) deleted in E4, the function of the E4 region must be supplied to the recombinant virus by a helper virus or packaging cell line. However, useful packaging cell lines have not been available because normally the continuous expression of functioning Ad E1 and functional E4 in a single cell line are toxic to the cell. Such cells are therefore not useful for the growth and replication of recombinant adenoviruses. Further, the DNA encoding the functional Ad E1 and Ad E4 genes, when present in a packaging cell line, can increase the chances of recombination with a recombinant Ad virus to cause the virus to revert to a wildtype Ad virus.

[0026] The present invention avoids these problems by providing a packaging cell line which contains the Ad5 E1 gene and only the ORF 6 of the Ad5 E4 gene. ORF6 of E4 alone can provide the requirements for E4 in the viral life cycle. According to this invention, the ORF6 is further preferably under the transcriptional control of an inducible promoter, such as the sheep metallothionine promoter, inducible by zinc, or the mouse mammary tumor virus (MMTV) promoter, inducible by a glucocorticoid, particularly, dexamethasone. This packaging cell line permits one to control the development of toxicity by regulating the expression of the E4 ORF6 gene. After the desired shuttle vector containing the adenoviral sequences is transfected into the cell line, expression of the E4 ORF6 can be induced by the appropriate inducer. The packaging cell is thus able to provide both Ad E1 and Ad E4 ORF6 gene products to the recombinant virus for a sufficient period to allow productive infection and recovery of the recombinant virus, before the cell becomes toxic. At present, the time period before the cell experiences toxicity is about 10 days.

[0027] In its most preferred form, the packaging cell line is a human embryonic kidney (HEK) 293 E1 expressing cell line into which is introduced the E4 ORF 6 sequence under the control of an inducible promoter. The MMTV promoter with its glucocorticoid inducer is presently preferred, because the zinc sulfate inducer of the MT promoter can itself be toxic to the cells. However, other inducible promoters, such as those identified in International patent application WO95/13392, published May 18, 1995, and incorporated by reference herein may also be used in the production of packaging cell lines according to this invention. Constitutive promoters in control of the expression of ORF6 may be employed, such as the constitutive Ad5 E4 region promoter, LTR, but are less preferred.

[0028] It should be understood by one of skill in the art that another parent cell line may be selected for the generation of a novel cell line expressing the E1a, E1b, and E4 ORF6 genes of a selected adenovirus serotype. Among such parent cell lines may be included HeLa [CCL 2], A549 [CCL 185], KB [CCL 17], Detroit [e.g., Detroit 510, CCL 72] and WI-38 [ATCC CCL 75] cells. These cell lines are all available from the American Type Culture Collection, 10801 University Boulevard, Manassas, Va. 20110-2209. Other suitable parent cell lines may be obtained from other sources. If such parent cell lines were selected for modification, the cell line would need to be further supplied with the E1a and E1b gene functions, e.g., such as by transfection with a plasmid containing these genes or functional fragments thereof under a suitable promoter, as well as with the ORF6 gene as described herein.

[0029] Example 1 below provides specific teaching of the construction of packaging cell lines containing only the ORF 6 of Ad5 E4 region or, for functional comparisons, the entire E4 region. Briefly described, the entire E4 region and an ORF6 sequence of Ad 5 E4 gene were obtained by known techniques [see, e.g., Sambrook et al., "Molecular Cloning. A Laboratory Manual.", 2d edit., Cold Spring Harbor Laboratory, New York (1989) and references cited therein]. To isolate the ORF6 region, the anchored polymerase chain reaction technique was used to amplify the ORF6 sequence from its initiation codon to its termination codon. Primers selected from the published sequence of ORF6 were used to amplify the ORF sequence and insert restriction sites onto the end of the sequence. The E4 ORF6 sequence itself is reproduced as nucleotides 1523 through 2408 of SEQ ID NO: 1 in FIG. 2. The entire E4 gene sequence is published in the Genbank sequence of Ad5 [Genbank Accession No. M73260].

[0030] A minigene was constructed that placed the ORF6 sequence under the control of a selected promoter. By "minigene" as used here is meant the combination of the ORF6 sequence and the other regulatory elements necessary to transcribe the sequence and express the gene product in a cell containing that minigene. The ORF6 sequence gene is operatively linked to regulatory components in a manner which permits its transcription. Such components include conventional regulatory elements, such as a promoter to drive ORF6 expression. One inducible promoter was an Zn.sup.+2 inducible sheep metallothionine (MT) promoter [M. G. Peterson et al, Eur. J. Biochem., 174:417-424 (1988)]. The second promoter, i.e, the promoter exemplified in FIG. 2, is the dexamethasone-inducible mouse mammary tumor virus (MMTV) promoter. The DNA sequence of the MMTV promoter spans nucleotides 1-1506 of SEQ ID NO: 1 in FIG. 2.

[0031] The minigene also contains nucleic acid sequences heterologous to the ORF6 viral sequence, including sequences providing signals required for efficient polyadenylation of the transcript (poly-A or pA). A common poly-A sequence which is employed in this invention is that derived from the growth hormone (GH) gene terminator sequence. The poly-A sequence generally is inserted in the minigene following the ORF6 sequence. The polyA sequence employed in the MMTV-ORF6 minigene described in Example 1 and FIG. 2 is supplied by the growth hormone gene terminator, which spans nucleotides 2409-3654 of SEQ ID NO: 1 in FIG. 2 and an SV40 origin of replication. A similar minigene differing in promoter sequence, polyA sequence and/or SV40 origin of replication sequence can also be designed by one of skill in the art to transfer the E4 ORF6 sequence to a shuttle plasmid. Selection of these and other common vector elements are conventional [see, e.g., Sambrook et al, "Molecular Cloning. A Laboratory Manual.", 2d edit., Cold Spring Harbor Laboratory, New York (1989) and references cited therein] and many such sequences are available from commercial and industrial sources as well as from Genbank.

[0032] The ORF6-containing minigene was subcloned into a pBR322-based shuttle plasmid that contained a neomycin resistance gene, resulting in the shuttle vector depicted in FIG. 1. Any of the many known bacterial shuttle vectors may be employed to carry the minigene, providing that the vector contains a reporter gene or selectable marker of which many, e.g., neo, amp or purimycin, are known in the art. It is expected that one of skill in the art can develop other suitable shuttle vectors using other plasmid components which are similarly capable of transferring the ORF6 minigene into the chromosome of a cell transfected with the plasmid.

[0033] As further described in Example 1, other shuttle vectors were designed for comparative purposes, which contain the complete or substantially complete Ad5 E4 region under the control of the constitutive retroviral MLV LTR sequence in the presence or absence of the endogenous E4 promoter. The shuttle plasmid carrying the ORF6 minigene (or the entire E4 region) was introduced into HEK 293 cells which express the Ad E1 gene products. Complementing cell lines were generated that express these Ad E4 or ORF6 genes from either their endogenous promoters or heterologous inducible promoters. These cell lines are further characterized by their genetic constitution, E4 protein synthesis, recombinant AAV helper function, relative plaque efficiency of H5dl1004 virus, and growth kinetics of recombinant E1/E4 deleted adenovirus. These characteristics of exemplary E1/E4 expressing packaging cell lines are discussed in detail in the following examples.

[0034] The E1/E4 ORF6 expressing packaging cell lines are useful in the generation of recombinant E1/E4 deleted adenoviruses. These recombinant adenoviruses are useful in transferring a selected transgene to a selected cell. In in vivo experiments with the recombinant virus grown in the packaging cell lines, the E1/E4 deleted recombinant virus demonstrated utility particularly in transferring a transgene to a muscle cell.

II. Recombinant Adenovirus

[0035] The novel E1/E4 expressing cell line is useful in further constructing E1/E4 deleted recombinant adenoviruses containing any selected transgene. The recombinant adenoviruses of this invention are capable of delivering a suitable gene to mammalian cells and tissues. These recombinant adenoviruses are functionally deleted in at least the E1a, E1b and E4 Ad gene regions. By the term "functionally deleted" is meant that a sufficient amount of the gene region is removed or otherwise damaged, e.g., by mutation or modification, so that the gene region is no longer capable of producing the products of gene expression. If desired, the entire gene region may be removed.

[0036] The adenovirus sequences used in the construction of the shuttle vectors, helper viruses, if needed, and recombinant viruses, and other components and sequences employed in the construction of the vectors and viruses described herein may be readily obtained from commercial or academic sources based on previously published and described sequences. Viral materials may also be obtained from an individual patient. The viral sequences and vector components may be generated by resort to the teachings and references contained herein, coupled with standard recombinant molecular cloning techniques known and practiced by those skilled in the art. Modifications of existing nucleic acid sequences forming the vectors, including sequence deletions, insertions, and other mutations taught by this specification may be generated using standard techniques. Similarly, the methods employed for the selection of viral sequences useful in a vector, the cloning and construction of the "minigene" and its insertion into a desired viral shuttle vector and the production of a recombinant infectious virus are within the skill in the art given the teachings provided herein.

A. Construction of the Transgene containing "Minigene"

[0037] A "minigene" in this context is defined as above, except that the components of this minigene are designed to express the gene product in vivo. Such components include conventional regulatory elements necessary to drive expression of the transgene in a cell transfected with the recombinant virus. For this minigene, a selected promoter is operatively linked to the transgene and located, with other regulatory elements, within the selected viral sequences of the recombinant vector. Selection of the promoter is a routine matter and is not a limitation of this invention. Useful promoters may be constitutive promoters or regulated (inducible) promoters, which will enable control of the amount of the transgene to be expressed. For example, a desirable promoter is that of the cytomegalovirus (CMV) immediate early promoter/enhancer [see, e.g., Boshart et al, Cell, 41:521-530 (1985)]. Another desirable promoter includes the Rous sarcoma virus LTR promoter/enhancer. Still another promoter/enhancer sequence is the chicken cytoplasmic .beta.-actin (CB) promoter [T. A. Kost et al, Nucl. Acids Res., 11(23) :8287 (1983)]. Other suitable promoters may be selected by one of skill in the art.

[0038] The minigene may also desirably contain nucleic acid sequences heterologous to the viral vector sequences including poly-A sequences and introns with functional splice donor and acceptor sites, as described above. The poly-A sequence generally is inserted in the minigene following the transgene sequences and before the 3' adenovirus sequences. A minigene of the present invention may also contain an intron, desirably located between the promoter/enhancer sequence and the transgene. Selection of these and other common vector elements are conventional as described above and many such sequences are available from commercial and industrial sources as well as from Genbank.

[0039] As above stated, the minigene is located in the site of any selected deletion in the recombinant adenovirus. In the exemplary E1/E4 deleted recombinant adenovirus H5.001CBLacZ, the transgene is located in the deleted E1 gene region. However, the transgene may be located elsewhere in the adenovirus sequence, as desired.

B. Production of Recombinant Adenovirus

[0040] Adenovirus sequences useful in this invention may include the DNA sequences of a number of adenovirus types, which are available from Genbank, including type Ad5 [Genbank Accession No. M73260]. The adenovirus sequences may be obtained from any known adenovirus serotype, such as serotypes 2, 3, 4, 7, 12 and 40, and further including any of the presently identified 41 human types [see, e.g., Horwitz, cited above]. Similarly, adenoviruses known to infect other animals may also be employed in the vector constructs of this invention. The selection of the adenovirus type is not anticipated to limit the following invention. A variety of adenovirus strains are available from the American Type Culture Collection, Manassas, Virginia, or available by request from a variety of commercial and institutional sources. In the following exemplary embodiment an adenovirus, type 5 (Ad5) is used for convenience.

[0041] However, it is desirable to obtain a variety of adenovirus shuttle vectors based on different human adenovirus serotypes. It is anticipated that a library of such plasmids and the resulting recombinant adenoviruses would be useful in a therapeutic regimen to evade cellular, and possibly humoral, immunity, and lengthen the duration of transgene expression, as well as improve the success of repeat therapeutic treatments. Additionally the use of various serotypes is believed to produce recombinant viruses with different tissue targeting specificities. Additionally, the absence of adenoviral genes E1 and E4 in the recombinant adenovirus of this invention should reduce or eliminate adverse CTL responses which normally cause destruction of recombinant adenoviruses deleted of only the E1 gene.

[0042] Recombinant adenoviruses of this invention are recombinant, defective adenoviruses (i.e., E1 deleted) which are also deleted completely or functionally of the E4 gene region. Functional deletions of E4 gene regions may be assessed by assays of Examples 2 and 3, among other assays. Recombinant adenoviruses of useful in this invention may optionally bear other mutations, e.g., temperature sensitive mutations in the E2a gene region, and deletions in the E3 gene regions.

[0043] An adenovirus of this invention contains a functional deletion of the adenoviral early immediate early gene E1a (which spans mu 1.3 to 4.5) and delayed early gene E1b (which spans mu 4.6 to 11.2). Similarly the adenovirus has a functional deletion of the E4 region (which spans mu 92 to 97.2), or at least of ORF6 of the E4 region.

[0044] Gene regions which may be optionally deleted in the E1/E4 deleted recombinant viruses of this invention include all or a portion of the adenovirus delayed early gene E3 (which spans mu 76.6 to 86.2). The function of E3 is irrelevant to the function and production of the recombinant virus particle.

[0045] The recombinant adenovirus of this invention may also have a mutation which results in reduced expression of adenoviral protein and/or reduced viral replication. For example, a temperature-sensitive mutation may be introduced into the adenovirus delayed early gene E2a (which spans mu 67.9 to 61.5). Among such mutations include the incorporation of the missense temperature-sensitive (ts) mutation in the (DBP) E2a region found in the Ad5 H5ts125 strain [P. Vander Vliet et al, J. Virol., 15:348-354 (1975)] at 62.5 mu. A single amino acid substitution (62.5 mu) at the carboxy end of the 72 kd protein produced from the E2a gene in this strain produces a protein product which is a single-stranded DNA binding protein and is involved in the replication of adenoviral genomic DNA. At permissive temperatures (approximately 32.degree. C. ) the ts strain is capable of full life cycle growth on HeLa cells, while at non-permissive temperatures (approximately 38.degree. C. ) no replication of adenoviral DNA is seen. In addition, at non-permissive temperatures, decreased immunoreactive 72 kd protein is seen in HeLa cells. See, e.g., J. F. Engelhardt et al, Hum. Gene Ther., 5:1217-1229 (1994); J. F. Engelhardt et al, Proc. Natl. Acad. Sci., USA, 91:6196-6200 (1994) and International patent application Ser. No. WO95/13392, published May 18, 1995, incorporated by reference herein.

[0046] However, it should be understood that other deletions in the adenovirus genome as previously described in the art or otherwise may also occur in the recombinant viruses of this invention. One minimal type of recombinant adenovirus can contain adenovirus genomic sequences from which all viral genes are deleted. More specifically, the adenovirus sequences may be only the cis-acting 5' and 3' inverted terminal repeat (ITR) sequences of an adenovirus (which function as origins of replication) and the native 5' packaging/enhancer domain, that contains sequences necessary for packaging linear Ad genomes and enhancer elements for the E1 promoter. The adenovirus 5' sequence containing the 5' ITR and packaging/enhancer region (Ad5 mu 0-1 or bp 1-360) can be employed as the 5' adenovirus sequence in recombinant adenoviruses of this invention. The 3' adenovirus sequences including the right terminal (3') ITR sequence of the adenoviral genome spanning about bp 35,353--end of the adenovirus genome, or map units .sup..about.98.4-100 may be desirably employed as the 3' sequence of the recombinant adenovirus. These sequences, which are clearly devoid of the E1 and E4 genes, can flank, or be operatively associated with the minigene in a recombinant virus. Any other necessary Ad gene products will then be supplied by helper viruses and the E1/E4 ORF6 expressing packaging cell of this invention.

[0047] Exemplary recombinant adenoviruses for use in this invention, for example, may be obtained by homologous recombination of desired fragments from various recombinant adenoviruses, a technique which has been commonly employed to generate other recombinant adenoviruses for gene therapy use. In the examples below, a representative recombinant adenovirus, H5.001CBLacZ, is constructed by homologous recombination between the adenovirus dl1004 (also H5dl1004) viral backbone and pAdCBLacZ minigene DNA. H5dl1004 is an Ad5 virus deleted of from about map unit 92.1 through map unit 98, i.e, substantially the entire E4 gene. The dl1004 virus is described in Bridge and Ketner, J. Virol., 632(2) :631-638 (Feb. 1989), incorporated by reference herein.

[0048] The pAdCBLacZ vector is a cDNA plasmid containing Ad m.u. 0-1, an E1 deletion into which is inserted a bacterial .beta.-galactosidase gene under the control of a chicken .beta.-actin promoter, with other regulatory elements as described below, and flanked by Ad m.u. 9-16 and plasmid sequence.

[0049] The production of the E1/E4 recombinant adenovirus of this invention in the novel packaging cell line of this invention utilizes conventional techniques. Such techniques include conventional cloning techniques of cDNA such as those described in texts [Sambrook et al, cited above], use of overlapping oligonucleotide sequences of the adenovirus genomes, polymerase chain reaction, and any suitable method which provides the desired nucleotide sequence. Standard transfection and co-transfection techniques are employed, e.g., CaPO.sub.4 transfection techniques using the complementation 293 cell line. Other conventional methods employed include homologous recombination of the viral genomes, plaquing of viruses in agar overlay, methods of measuring signal generation, and the like.

[0050] For example, following the construction and assembly of the desired minigene-containing plasmid vector pAdCBLacZ, the E1/E4 expressing packaging cell line of this invention is infected with the helper virus H5dl1004. The infected cell line is then subsequently transfected with the an adenovirus plasmid vector by conventional methods. Homologous recombination occurs between the E4-deleted H5dl1004 helper and the pAdCBLacZ vector, which permits the adenovirus-transgene sequences in the vector to be replicated and packaged into virion capsids, resulting in the recombinant virus. About 30 or more hours post-transfection, the cells are harvested, an extract prepared and the recombinant virus containing the LacZ transgene is purified by buoyant density ultracentrifugation in a CsCl gradient.

III. Use of the Recombinant Virus in Gene Therapy

[0051] The resulting recombinant adenovirus containing the transgene produced by cooperation of the adenovirus vector and E4 deleted helper virus and packaging cell line, as described above, thus provides an efficient gene transfer vehicle which can deliver the transgene to a patient in vivo or ex vivo and provide for integration of the gene into a mammalian cell.

[0052] The above-described recombinant viruses are administered to humans in a conventional manner for gene therapy and serve as an alternative or supplemental gene therapy for the disorder to which the transgene is directed. A recombinant adenovirus of this invention may be administered to a patient, preferably suspended in a biologically compatible solution or pharmaceutically acceptable delivery vehicle. A suitable vehicle includes sterile saline. Other aqueous and non-aqueous isotonic sterile injection solutions and aqueous and non-aqueous sterile suspensions known to be pharmaceutically acceptable carriers and well known to those of skill in the art may be employed for this purpose.

[0053] The recombinant viruses are administered in sufficient amounts to transfect the desired target cells, e.g., muscle, liver, epithelial, etc. and provide sufficient levels of transfer and expression of the transgene to provide a therapeutic benefit without undue adverse or with medically acceptable physiological effects which can be determined by those skilled in the medical arts. Conventional and pharmaceutically acceptable routes of administration include direct delivery to the muscle or other selected cell, intranasal, intravenous, intramuscular, subcutaneous, intradermal, oral and other parental routes of administration. Routes of administration may be combined, if desired.

[0054] Dosages of recombinant virus will depend primarily on factors such as the condition being treated, the age, weight and health of the patient, and may thus vary among patients. For example, a therapeutically effective human dose of the recombinant adenovirus is generally in the range of from about 20 to about 100 ml of saline solution containing concentrations of from about 1.times.10.sup.9 to 1.times.10.sup.11 pfu/ml virus. A preferred human dose is estimated to be about 50 ml saline solution at 2.times.10.sup.10 pfu/ml. The dose will be adjusted to balance the therapeutic benefit against any side effects. The levels of expression of the transgene can be monitored to determine the frequency of administration.

[0055] An optional method step involves the co-administration to the patient, either concurrently with, or before or after administration of the recombinant virus of a suitable amount of a short acting immune modulator. The selected immune modulator is defined herein as an agent capable of inhibiting the formation of neutralizing antibodies directed against the recombinant vector of this invention or capable of inhibiting or substantially delaying cytolytic T lymphocyte (CTL) elimination of the vector. Among desirable immune modulators are interleukin-12 [European Patent Application No. 441,900]; gamma interferon [S. C. Morris et al, J. Immunol., 152:1047 (1994)]; interleukin-4 [U.S. Pat. No. 5,017,691]; antibody to the CD4 protein, such as anti-OKT 3+ [see, e.g., U.S. Pat. No. 4,658,019] or antibody GK1.5 (ATCC Accession No. TIB207); a soluble CD40 molecule or an antibody to CD40 ligand (Bristol-Myers Squibb Co) [European patent application 555,880, published Aug. 18, 1993]; a soluble form of B7 or an antibody to CD28 or CTLA4 [CTLA4-Ig (Bristol-Myers Squibb Co), European patent application 606,217, published Jul. 20, 1994], or agents such as cyclosporin A or cyclophosphamide.

[0056] Thus, the compositions and methods of this invention provide a desirable gene therapy treatment.

[0057] The following examples illustrate the construction and testing of the novel packaging cell lines, the E1/E4 deleted recombinant adenovirus of the present invention and the use thereof. These examples are illustrative only, and do not limit the scope of the present invention.

EXAMPLE 1

Novel E1a/E1b and E4 Expressing Packaging Cell Lines

A. Construction of E4 ORF 6 Expressing Plasmids

[0058] 1. pMTE4ORF6

[0059] One exemplary plasmid useful for the construction of a packaging cell line of this invention is pMTE4ORF6, which contains a sheep metallothionine promoter (MT promoter) [M. G. Peterson et al, cited above] in control of the transcription of a human E4 ORF 6 gene sequence (nucleotides 1521 to 2406 of SEQ ID NO: 1 in FIG. 2), a growth hormone terminator (GH), an SV40 origin of replication, plasmid sequences from pBR322-based plasmid including a neomycin resistance gene, an SV40 polyadenylation site and an ampicillin resistance gene.

[0060] The various functional fragments of this plasmid may be readily replaced with other conventionally used sequences and are not critical to the design of the plasmid.

[0061] 2. pMMTVE4ORF6

[0062] Another exemplary plasmid useful for the construction of a packaging cell line of this invention is pMMTVE4ORF6, which contains a mouse mammary tumor virus promoter (MMTV) (nucleotides 1-1506 of SEQ ID NO:1 in FIG. 2) in transcriptional control of a human E4 ORF 6 gene sequence (nucleotides 1523-2408 of SEQ ID NO: 1 in FIG. 2), a growth hormone terminator (GH) (nucleotides 2409-3654 of SEQ ID NO: 1 in FIG. 2), an SV40 origin of replication, plasmid sequences from plasmid pBR322, including a neomycin resistance gene, and an ampicillin resistance gene. The various functional fragments of this plasmid may be readily replaced with other conventionally used sequences and are not critical to the design of the plasmid.

[0063] 3. pLTR.E4(-) Endogenous E4 Promoter

[0064] A plasmid used as a control for the construction of a packaging cell line of this invention is pLTR.E4(-). This plasmid contains the constitutive retroviral MLV LTR and most of the Ad E4 gene region except that the endogenous E4 promoter and a portion of E4 ORF1 are missing. The other plasmid sequences remain the same as described above.

[0065] 4. pLTR.E4(+) Endogenous E4 Promoter

[0066] Still another plasmid useful for the study of the methods of this invention is pLTR.E4, which contains the constitutive MLV LTR and endogenous E4 promoter and an intact E4 gene. The other plasmid sequences remain the same as described above.

B. Transfections and Selection of Clones

[0067] Each of the above-described plasmids was transfected by the calcium phosphate precipitation technique into the human embryonic kidney cell line 293 [ATCC CRL1573] which expresses the product of the adenovirus E1 genes, seeded on 100 mm plates (10 .mu.g plasmid/plate). Twenty four hours post-transfection, cells were harvested and seeded at varying dilutions (1:10-1:100) in 100 mm plates for about 10 days. Seeding media contain G418 (Geneticin, BRL) at 1 mg/ml. Resistant colonies that developed were selected using the following assays and expanded. Preliminary analysis of clones was based on enhanced transduction efficiency of a recombinant adeno-associated virus, AV.CMVLacZ, and immunofluorescence localization of Ad E4 protein as described in the following examples.

EXAMPLE 2

AV-CMVLacZ Transduction Enhancement Assay

[0068] E1 and E4 Ad gene products are needed for recombinant adeno-associated virus (AAV) function. This primary assay involves seeding the packaging cell lines of Example 1 in 96 well 35 mm culture plates (2.times.10.sup.6 cells/well) and infecting the cells with purified, heat-treated AV.CMVLacZ at an MOI of 1000 virus particles/cell.

A. Preparation of AV.CMVLacZ

[0069] A recombinant AAV virus was prepared by conventional genetic engineering techniques for the purposes of this experiment. Recombinant AAV was generated by plasmid transfections in the presence of helper adenovirus [Samulski et al, J. Virol., 63:3822-3828 (1989)]. A cis-acting plasmid pAV.CMVLacZ was derived from psub201 [Samulski et al, J. Virol., 61:3096-3101 (1987)] and contains an E. coil .beta. galactosidase minigene in place of AAV Rep and Cap genes. The 5' to 3' organization of the recombinant AV.CMVLacZ genome (4.9 kb) includes

[0070] (a) the 5' AAV ITR (bp 1-173) was obtained by PCR using pAV2 [C. A. Laughlin et al, Gene, 23: 65-73 (1983)] as template;

[0071] (b) a CMV immediate early enhancer/promoter [Boshart et al, Cell, 41:521-530 (1985)];

[0072] (c) an SV40 intron;

[0073] (d) E. coli beta-galactosidase cDNA;

[0074] (e) an SV40 polyadenylation signal (a 237 Bam HI-BclI restriction fragment containing the cleavage/poly-A signals from both the early and late transcription units; and

[0075] (f) 3' AAV ITR, obtained from pAV2 as a SnaBI-BglII fragment.

[0076] Rep and Cap genes were provided by a trans-acting plasmid pAAV/Ad [Samulski et al, cited above].

[0077] Monolayers of 293 cells grown to 90% confluency in 150 mm culture dishes (5.times.10.sup.7 cells/plate) were infected with H5.CBALP at an MOI of 10. H5.CBALP (also called H5.010ALP) is a recombinant adenovirus that contains an alkaline phosphatase minigene in place of adenovirus E1a and E1b gene sequences (map units 1-9.2 of the Ad5 sequence of GenBank [Accession No. M73260]). The alkaline phosphatase cDNA is under the transcriptional control of a CMV-enhanced .beta.-actin promoter in this virus. This helper virus is described in Goldman et al, Hum. Gene Ther., 6:839-851 (July, 1995); Engelhardt et al, Hum. Gene Ther., 5:1217-1229 (October, 1994); and references cited therein.

[0078] Infections were done in Dulbecco's Modified Eagles Media (DMEM) supplemented with 2% fetal bovine serum (FBS) at 20 ml media/150 mm plate. Two hours post-infection, 50 .mu.g plasmid DNA (37.5 .mu.g trans-acting and 12.5 .mu.g cis-acting) in 2.5 ml of transfection cocktail was added to each plate and evenly distributed. Transfections were calcium phosphate based as described [B. Cullen, Meth. Enzymol., 152:684-704 (1987)]. Cells were left in this condition for 10-14 hours after which the infection/transfection media was replaced with 20 ml fresh DMEM/2% FBS. Forty to fifty hours post-transfection, cells were harvested, suspended in 10 mM Tris-Cl (pH 8.0) buffer (0.5 ml/150 mm plate) and a lysate prepared by sonication. The lysate was brought to 10 mM manganese chloride, after which bovine pancreatic DNase I (20,000 units) and RNase (0.2 mg/ml final concentration) were added, and the reaction incubated at 37.degree. C. for 30 minutes. Sodium deoxycholate was added to a final concentration of 1% and incubated at 37.degree. C. for an additional 10 minutes.

[0079] The treated lysate was chilled on ice for 10 minutes and solid CsCl added to a final density of 1.3 g/ml. The lysate was brought to a final volume of 60 ml with 1.3 g/ml CsCl solution in 10 mM Tris-Cl (pH 8.0) and divided into three equal aliquots. Each 20 ml sample was layered onto a CsCl step gradient composed of two 9.0 ml tiers with densities 1.45 g/ml and 1.60 g/ml.

[0080] Centrifugation was performed at 25,000 rpm in a Beckman SW-28 rotor for 24 hours at 4.degree. C.

[0081] Fractions containing peak titers of functional AV.CMVLacZ virus were combined and subjected to three sequential rounds of equilibrium sedimentation in CsCl. Rotor selection included a Beckman NVT-90 (80,000 rpm for 4 hours) and SW-41 (35,000 rpm for 20 hours). At equilibrium, AV.CMVLacZ appeared as an opalescent band at 1.40-1.41 g/ml CsCl. Densities were calculated from refractive index measurements. Purified vector was exchanged to 20 mM HEPES buffer (pH7.8) containing 150 mM NaCl (HBS) by dialysis and stored frozen at -80.degree. C. in the presence of 10% glycerol or as a liquid stock at -20.degree. C. in HBS/40% glycerol.

[0082] Purified virus was tested for contaminating H5.CBALP helper virus and AV.CMVLacZ titers. Helper virus was monitored by histochemical staining for reporter alkaline phosphatase activity. A sample of purified virus representing 1.0% of the final product was added to a growing monolayer of 293 cells seeded in a 60 mm plate. Forty-eight hours later, cells were fixed in 0.5% glutaraldehyde/phosphate buffered saline (PBS) for 10 minutes at room temperature, washed in PBS (3.times.10 minutes) and incubated at 65.degree. C. for 40 minutes to inactivate endogenous alkaline phosphatase activity. The monolayer was allowed to cool to room temperature, rinsed once briefly in 100 mM Tris-Cl (pH9.5)/100 mM NaCl/5 mM MgCl, and incubated at 37.degree. C. for 30 minutes in the same buffer containing 0.33 mg/ml nitroblue tetrazolium chloride (NBT) and 0.165 mg/ml 5-bromo-4-choro-3-indolphosphate p-toluidine salt (BCIP). Color development was stopped by washing the monolayer in 10 mM Tris-Cl (pH 8.0)/5 mM EDTA. Routinely the purification scheme described above removed all detectable H5.CBALP helper virus by the third round of buoyant density ultracentrifugation.

[0083] AV.CMVLacZ titers were measured according to genome copy number (virus particles/ml), absorbance at 260 nm (A.sub.260 particles/ml) and LacZ Forming Units (LFU/ml). Virus particle concentrations were based on Southern blotting. Briefly, a sample of purified AV.CMVLacZ was treated with capsid digestion buffer (50 mM Tris-Cl, pH 8.0/1.0 mM EDTA, pH 8.0/0.5% SDS/Proteinase K 1.0 mg/ml) at 50.degree. C. for one hour to release virus DNA. The reactions were allowed to cool to room temperature, loading dye was added and electrophoresed through a 1.2% agarose gel. Standard quantities of ds AV.CMVLacZ genome were also resolved on the gel.

[0084] DNAs were electroblotted onto a nylon membrane, hybridized with a .sup.32P random primer labeled restriction fragment, and the resulting blot scanned on a PhosphorImager 445 SI (Molecular Dynamics). A standard curve was generated from the duplex forms and used to extrapolate the number of virus genomes in the sample. LFU titers were generated by infecting indicator cells with limiting dilutions of virus sample. Indicator cells included HeLa and 293. Twenty-four hours later, cells were fixed in glutaraldehyde and cells were histochemically stained for E. coli .beta.-galactosidase (LacZ) activity as described in J. M. Wilson et al, Proc. Natl. Acad. Sci. USA, 85:3014-3018 (1988). One LFU is described as the quantity of virus that is sufficient to cause visually detectable .beta.-galactosidase expression in one cell 24 hours post-infection.

B. Induction of ORF6 Expression

[0085] Induction of ORF6 expression with 10 .mu.M dexamethasone or 150 .mu.M zinc sulfate (for negative control, no inducer used) was initiated 2 hours before the addition of virus and continued throughout the duration of the experiment. Twenty-four hours after the addition of virus, cells were harvested, lysates were generated by sonication and analyzed for the .beta.-galactosidase expression (i.e., .beta.-galactosidase activity) and virus DNA as described above. Hirt extracts were prepared from low molecular weight DNA from cell extracts. The preparation of the Hirt extracts and subsequent analysis by Southern hybridization were performed by resort to conventional procedures known to one of skill in the art.

[0086] In the absence of the inducers, the packaging cell lines generate lower levels of .beta.-galactosidase in rAAV infected cells. Induction of ORF6 expression with the inducer dexamethasone results in a concomitant rise in AV.CMVLacZ cell transduction to a level that was much greater than the parent 293 line. Expression of E1 alone was insufficient to have an effect in the adenovirus mediated augmentation of rAAV transduction.

[0087] Results are demonstrated for certain positive clones in the Table I below (see Example 4). However, for 30 cell lines having an MMTV promoter and ORF6 sequence, 4 demonstrated over 90% blue cells illustrative of LacZ production in the presence of dexamethasone, i.e., 293-27-6, 293-27-17, 293-27-18 and 293-27-28.

EXAMPLE 3

Immunofluorescence Localization of Ad5 Late Protein

[0088] Positive clones from the assay of Example 2 were infected with the recombinant E4 deleted adenovirus H5dl1004 and screened for E4 complementation using an immunofluorescence assay for late gene expression. The H5dl1004 virus was obtained from Dr. Ketner of Johns Hopkins University and is described in Bridge and Ketner, J. Virol., 632(2) :631-638 (Feb. 1989), incorporated by reference herein. Because ORF6 of E4 complements late Ad gene expression, specifically in the formation of the hexon and penton fibers of the adenovirus, cell lines containing ORF6 are able to bind with antibody against these proteins.

[0089] Each cell line of Example 1 is infected with E4 deleted virus H5dl1004 virus at an MOI of 0.1. The cells were treated with mouse anti-adenovirus FITC-labeled monoclonal antibody to either the hexon or penton fibers in a 1:10 dilution (Chemicon International Inc., Temecula, Calif. ). Positive clones were identified by reaction with the antibody.

EXAMPLE 4

Relative Plaguing Efficiency

[0090] The cell lines of Example 1 demonstrating with strong complementation ability in Example 3 were screened for relative plaquing efficiency of H5dl1004 as compared to W162 cells (an E4-complementing Vero cell line which does not express E1) [Weinberg and Ketner, Proc. Natl. Acad. Sci, USA, 80(17) :5383-5386 (1983)]. In Table II below, RPE%, i.e., relative plaguing efficiency, represents the titer of H5dl1004 on tested cell lines/titer of H5dl1004 on W162 cells. For example, the RPE of 293 cells is 0.

[0091] The positive cell lines selected by all criteria are identified in Table I below, with the results of the assays of Examples 2, 3 and 4.

1TABLE I E1/E4 Double Complementing Cell Lines Cell Trans- Pro- AV.CMV Line Gene moter IF/LP LacZ RPE % 293-10-3 ORF6 MT ++++ ++++ 246 293-39-11 ORF6 LTR ++++ +++ 52 293-84-31 E4- LTR ++++ ++++ 179 293-12-31 whole LTR + ++++ ++++ 174 E4 E4 293-27-6 ORF6 MMTV +++++ 327 293-27-17 ORF6 MMTV ++++ 313 293-27-18 ORF6 MMTV +++++ 339 293-27-28 ORF6 MMTV ++++ 261

EXAMPLE 5

Construction and Purification of H5.001CBLacZ

[0092] The plasmid pAd.CBLacZ was constructed as described in detail in K. Kozarsky et al, Som. Cell Mol. Genet., 19(5): 449-458 (1993), incorporated by reference herein. This plasmid contained a minigene comprising a 5' flanking NheI restriction site, followed by Ad5 sequence m.u. 0-1, followed by an E1 deletion into which is inserted a CMV enhancer/chicken .beta.-actin promoter sequence [T. A. Kost et al, Nucl. Acids Res., 11(23) :8287 (1983)], which controls the transcription of the following bacterial .beta.-galactosidase, followed by a poly A sequence and flanked 3' by Ad m.u. 9-16, and another NheI site. In the plasmid, the minigene was flanked on both sides by plasmid sequence containing drug resistance markers.

[0093] The plasmid pAd.CBLacZ was linearized with NheI and co-transfected by the calcium phosphate co-transfection method into the novel packaging cell line of Example 1 with ClaI digested H5dl1004 (an Ad5 sequence deleted of from about map unit 92.1 through map unit 98, corresponding to substantially the entire E4 gene).

[0094] Homologous recombination occurs in the cell line between these two viral constructs between Ad map units 9-16, resulting in recombinant adenovirus, designated H5.001CBLacZ (FIGS. 3 and 4 ). This recombinant adenovirus contains the sequence from about nucleotide 1 to about 4628 from pAd.CBLacZ and Ad5 map units 9-92.1 and 97.3 to 100 from H5dl1004. This recombinant adenovirus is thereby functionally deleted, and substantially structurally deleted, of the Ad E1 and E4 genes.

[0095] Viral plaques were selected and screened by the .beta.-galactosidase assay [Wilson (1988), cited above] and H5.001CBLacZ was isolated following three rounds of plaque purification. The purified virus was also subjected to cesium chloride density centrifugation and large scale production. For the following mouse experiments, virus was used after column purification and glycerol was added to a final concentration of 10% (v/v). Virus was stored at -70.degree. C. until use.

EXAMPLE 6

Growth Kinetics of H5.001CBLacZ in Packaging Cell Lines

[0096] The cell lines reported in Example 1 were infected with recombinant H5.001CBLacZ at an MOI of 0.5. The growth kinetics of this virus in the E4 complementing cell lines are shown in FIG. 5.

[0097] Maximum viral yield is reported as LFU/ml in Table II below.

2 TABLE II Cell Line Maximum Viral Yield 293-10-3 2.8 .times. 10.sup.10 293-39-11 9.5 .times. 10.sup.8 293-84-31 1.1 .times. 10.sup.9 293-12-31 4.5 .times. 10.sup.8 293-27-6 2.8 .times. 10.sup.10 293-27-17 2.5 .times. 10.sup.10 293-27-18 2.9 .times. 10.sup.10 293-27-28 1.2 .times. 10.sup.10

[0098] When grown in 293-27-18 cells (the E4 ORF6 cell line with MMTV promoter inducible by dexamethasone) the maximum yield of this virus is 2.9.times.10.sup.10 LFU/ml. Several of the cell lines were passaged between 5 and 20 times and the viral production of the passages remained stable. However, RPE did fall following repeated passages of cells.

EXAMPLE 7

Other Recombinant Adenoviruses

[0099] Other related recombinant adenoviruses were prepared similarly to H5.001CBLacZ by homologous recombination between pAdCBLacZ and other helper viruses.

[0100] As one example, H5.000CBLacZ is a recombinant E1 deleted Ad5 which contains the same minigene as H5.001CBLacZ, but has an intact E4 gene. This recombinant virus was prepared as described by homologous recombination between pAdCBLacZ and a wild-type Ad5.

[0101] As another example, H5.010CBLacZ contains the adenovirus map units 0-1, followed by a CMV enhanced, chicken cytoplasmic .beta.-actin promoter, the E. Coli beta-galactosidase gene (lacZ), a polyadenylation signal (pA), and adenovirus type 5 map units 9-100, with a small deletion in the E3 gene (the Ad 5 sub360 backbone). This recombinant virus may be prepared by homologous recombination between the pAdCBLacZ vector and Ad5 virus sub360, which contains a 150 bp deletion within the 14.6 kD protein of the E3 gene. See, e.g., J. F. Engelhardt et al, Proc. Natl. Acad. Sci., USA, 91:6196-6200 (June 1994); and Engelhardt et al, Hum. Gene Ther., 5:1217-1229 (Oct. 1994), both incorporated by reference herein.

[0102] These recombinant adenoviruses were isolated following transfection [Graham, Virol., 52:456-467 (1974)], and were subjected to two rounds of plaque purification. Lysates were purified by cesium chloride density centrifugation as previously described [Englehardt et al, Proc. Natl. Acad. Sci. USA, 88:11192-11196 (1991)]. Cesium chloride was removed by passing the virus over a BioRad DG10 column using phosphate-buffered saline.

EXAMPLE 8

LacZ Gene Transfer into Mouse

A. Transfer into Mouse Muscle

[0103] Five to six-week old male C57B/6 mice were anesthetized. Anterior tibialis muscles were exposed and directly injected with either recombinant adenovirus H5.000CBLacZ, H5.010CBLacZ or H5.001CBLacZ as follows: 25 .mu.L of purified viral suspension at a stock concentration of 5.times.10.sup.11 virus particles/mL was injected by inserting the tip of the 33 gauge needle of a 100 .mu.L Hamilton syringe into the belly of the muscle.

[0104] Animals were sacrificed on day 4, 14, 28 and 60 post injection. The muscles were dissected and frozen in liquid nitrogen cooled isopentane. Six .mu.M sections were cut in a cryostat, fixed and stained for .beta.-galactosidase activity for 6 hours at 37.degree. C.

[0105] While the blue stained recombinant virus was found for each virus in the day 4 and day 14 (most abundant) stains, by day 28, the H5.001CBLacZ clearly demonstrated more virus on day 28. By day 60, the only virus which stained positive was the H5.001CBLacZ.

B. Transfer into Mouse Lung and Circulation

[0106] Recombinant adenovirus H5.000CBLacZ (control), and H5.001CBLacZ (1.times.10.sup.11 viral particles) were administered to six week old C57BL/6 female mice by tail vein injection and trachea installation. The animals were sacrificed and their liver and lung tissues were harvested at days 4, 9, 21, 28 and 35 post-administration. The transgene and viral late gene expression were compared.

[0107] At therapeutic doses of virus, there was diminished expression of late viral proteins at all time points in comparison with transgene.

C. Dose Responses in Liver

[0108] Dose responses of E4-deleted and E4 intact recombinant adenoviruses in the liver of C57BL/6 mice were studied by tail vein administration of 1.5.times.10.sup.11, 5.times.10.sup.10, 1.7.times.10.sup.10, 5.6.times.10.sup.9, and 1.9.times.10.sup.9 viral particles and comparing the transgene and viral late gene expression at day 4, 21, 28, 35, and 42 post administration.

[0109] At therapeutic doses of virus, there was diminished expression of late viral proteins at all time points in comparison with transgene.

EXAMPLE 9

Other Gene Transfers

A. Human OTC Gene Transfer

[0110] The human OTC gene [A. L. Horwich et al, Science, 224:1068-174 (1984)] or the human CFTR gene [Riordan et al, Science, 245:1066-1073 (1989)] was used to replace the LacZ as the transgene in the recombinant E1/E4 deleted adenoviruses described above, using the techniques analogous for the construction of the above-described LacZ vectors.

[0111] The resulting human OTC-containing recombinant viruses were administered at an MOI of 10 to 30 to human hepatocytes. The E1/E4 deleted recombinant adenovirus demonstrated less replication and less late gene expression than when the E1/E4 deleted recombinant adenoviruses are administered to muscle, as described in the example above. However, the results of this gene transfer are better than comparable transfers with recombinant adenoviruses containing only a deletion in the E1 gene or a deletion in the E1 gene and a point mutation in the E2a gene.

[0112] Similar results are demonstrated when the transgene is CFTR and the method of administration is intratracheal into lungs.

[0113] All references recited above are incorporated herein by reference. Numerous modifications and variations of the present invention are included in the above-identified specification and are expected to be obvious to one of skill in the art. Such modifications and alterations to the compositions and processes of the present invention, such as selections of different transgenes and plasmids for the construction of the packaging cell lines and recombinant adenoviruses, or selection or dosage of the viruses or immune modulators, are believed to be within the scope of the claims appended hereto.

Sequence CWU 1

1

Claims

What is claimed is:

1. A packaging cell line which expresses an adenovirus E1 gene and an adenovirus E4 gene or a functional fragment of said E1 or E4 genes.

2. A stable packaging cell which comprises: (a) a first adenovirus DNA under the regulatory control of a first promoter, wherein said first adenovirus DNA encodes an adenovirus E1 protein; and (b) a second adenovirus DNA under the regulatory control of an inducible promoter, wherein said second adenovirus DNA encodes an adenovirus E4 ORF6 protein, wherein said packaging cell contains no other adenovirus E4 ORF DNA; and whereby, in the presence of an inducing agent, said E1 and E4ORF6 proteins are expressed in amounts sufficient to permit infection by, and recovery of, an adenovirus having functional deletions in its E1 and E4 genes.

3. The cell of claim 2, which is a human cell.

4. The cell of claim 2 in which the inducing agent is a metal.

5. The cell of claim 2 in which the metal is zinc.

6. The cell of claim 2 in which the inducing agent is a glucocorticoid.

7. The cell of claim 2 in which the inducing agent is dexamethasone.

8. The cell of claim 2 in which the first adenovirus DNA and the second adenovirus DNA are within the same nucleic acid molecule.

9. The cell of claim 2 in which the nucleic acid expressing the adenovirus E4ORF6 protein is pMMTVE4ORF6.

10. The cell of claim 2 in which the nucleic acid expressing the adenovirus E4ORF6 protein is pMTE4ORF6.

11. The cell of claim 2 which is 293 (MT-ORF6).

12. The cell of claim 2 which is HeLa (MT-ORF6).