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Westhaus A, Cabanes Creus M, Jonker T, Sallard E, Navarro RG, Zhu E, Baltazar G, Lee S, Wilmott P, Gonzalez-Cordero A, Santilli G, Thrasher AJ, Alexander IE, Lisowski L. AAV-p40 bioengineering platform for variant selection based on transgene expression. Hum Gene Ther 2022; 33:664-682. [PMID: 35297686 PMCID: PMC10112876 DOI: 10.1089/hum.2021.278] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The power of AAV directed evolution for identifying novel vector variants with improved properties is well established, as evidenced by numerous publications reporting novel AAV variants. However, most capsid variants reported to date have been identified using either replication-competent selection platforms or PCR-based capsid DNA recovery methods, which can bias the selection towards efficient replication or unproductive intracellular trafficking, respectively. A central objective of this study was to validate a functional transduction (FT)-based method for rapid identification of novel AAV variants based on AAV capsid mRNA expression in target cells. We performed a comparison of the FT platform to existing replication competent strategies. Based on the selection kinetics and function of novel capsids identified in an in vivo screen in a xenograft model of human hepatocytes, we identified the mRNA-based FT selection as the most optimal AAV selection method. Lastly, to gain insight into the mRNA-based selection mechanism driven by the native AAV-p40 promoter, we studied its activity in a range of in vitro and in vivo targets. We found AAV-p40 to be a ubiquitously active promoter that can be modified for cell type-specific expression by incorporating binding sites for silencing transcription factors, allowing for cell-type-specific library selection.
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Affiliation(s)
- Adrian Westhaus
- Children's Medical Research Institute, 58454, Translational Vectorology Group, 214 Hawkesbury Road, Westmead, New South Wales, Australia, 2145;
| | - Marti Cabanes Creus
- Children's Medical Research Institute, 58454, Translational Vectorology Group, Westmead, New South Wales, Australia;
| | - Timo Jonker
- Children's Medical Research Institute, 58454, Westmead, New South Wales, Australia;
| | - Erwan Sallard
- Children's Medical Research Institute, 58454, Westmead, New South Wales, Australia;
| | - Renina Gale Navarro
- Children's Medical Research Institute, 58454, Translational Vectorology Group, 214 Hawkesbury Road, Westmead, New South Wales, Australia, 2145;
| | - Erhua Zhu
- Children's Medical Research Institute, 58454, Gene Therapy Research Unit, Westmead, New South Wales, Australia;
| | - Grober Baltazar
- Children's Medical Research Institute, 58454, Translational Vectorology Group, Westmead, New South Wales, Australia;
| | - Scott Lee
- Children's Medical Research Institute, 58454, Westmead, New South Wales, Australia;
| | - Patrick Wilmott
- Children's Medical Research Institute, 58454, Translational Vectorology Group, 214 Hawkesbury Rd, Westmead, New South Wales, Australia, 2145;
| | - Anai Gonzalez-Cordero
- The University of Sydney Faculty of Medicine and Health, 522555, Stem Cell & Organoid Facility and Stem Cell Medicine Group, Children's Medical Research Institute, 214 Hawkesbury Road, Westmead, Sydney, New South Wales, Australia, 2145;
| | - Giorgia Santilli
- UCL-Institute of Child Health, Centre for Immunodeficiencies, 30 guilford street, London, United Kingdom of Great Britain and Northern Ireland, WC1N 1EH;
| | - Adrian J Thrasher
- Institute of Child Health, London, UK, Molecular Immunology Unit, 30 guilford street, london, United Kingdom of Great Britain and Northern Ireland, wc1n1eh;
| | - Ian Edward Alexander
- Sydney Children's Hospitals Network and Children's Medical Research Institute, Corner Hawkesbury Rd & Hainsworth St, Locked Bag 4001, Westmead, New South Wales, Australia, 2145 Sydney;
| | - Leszek Lisowski
- Children's Medical Research Institute, 58454, Translational Vectorology Research Unit, Westmead, New South Wales, Australia;
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2
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Abstract
The driving interest in adeno-associated virus (AAV) has been its potential as a gene delivery vector. The early observation that AAV can establish a latent infection by integrating into the host chromosome has been central to this interest. However, chromosomal integration is a two-edged sword, imparting on one hand the ability to maintain the therapeutic gene in progeny cells, and on the other hand, the risk of mutations that are deleterious to the host. A clearer understanding of the mechanism and efficiency of AAV integration, in terms of contributing viral and host-cell factors and circumstances, will provide a context in which to evaluate these potential benefits and risks. Research to date suggests that AAV integration in any context is inefficient, and that the persistence of AAV gene delivery vectors in tissues is largely attributable to episomal genomes.
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Affiliation(s)
- Douglas M McCarty
- School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
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3
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Gao G, Alvira MR, Somanathan S, Lu Y, Vandenberghe LH, Rux JJ, Calcedo R, Sanmiguel J, Abbas Z, Wilson JM. Adeno-associated viruses undergo substantial evolution in primates during natural infections. Proc Natl Acad Sci U S A 2003; 100:6081-6. [PMID: 12716974 PMCID: PMC156329 DOI: 10.1073/pnas.0937739100] [Citation(s) in RCA: 246] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adeno-associated viruses (AAVs) are single-stranded DNA viruses that are endemic in human populations without known clinical sequelae and are being evaluated as vectors for human gene therapy. To better understand the biology of this virus, we examined a number of nonhuman primate species for the presence of previously uncharacterized AAVs and characterized their structure and distribution. AAV genomes were widely disseminated throughout multiple tissues of a variety of nonhuman primate species. Surprising diversity of sequence, primarily localized to hypervariable regions of the capsid protein, was detected. This diversity of sequence is caused, in part, by homologous recombination of co-infecting parental viruses that modify the serologic reactivity and tropism of the virus. This is an example of rapid molecular evolution of a DNA virus in a way that was formerly thought to be restricted to RNA viruses.
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Affiliation(s)
- Guangping Gao
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
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4
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Cathomen T, Stracker TH, Gilbert LB, Weitzman MD. A genetic screen identifies a cellular regulator of adeno-associated virus. Proc Natl Acad Sci U S A 2001; 98:14991-6. [PMID: 11734633 PMCID: PMC64971 DOI: 10.1073/pnas.261567198] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adeno-associated virus type 2 (AAV2) is a human parvovirus that has attracted attention as a vector for gene transfer. Replication and site-specific integration of the wild-type virus requires binding of the AAV2 Rep proteins to a cis-regulatory element named the Rep recognition sequence (RRS). RRS motifs are found within the cellular AAVS1 integration locus, the viral p5 promoter, and the inverted terminal repeats (ITRs). Here we report the design of a genetic screen based on the yeast one-hybrid assay to identify cellular RRS-binding proteins. We show that the human zinc finger 5 protein (ZF5) binds specifically to RRS motifs in vitro and in vivo. ZF5 is a highly conserved and ubiquitously expressed transcription factor that contains five C-terminal zinc fingers and an N-terminal POZ domain. Ectopic expression of ZF5 leads to an ITR-dependent repression of the autologous p5 promoter and reduces both AAV2 replication and the production of recombinant AAV2. By using deletion and substitution mutants we show that two different domains of ZF5 contribute to AAV2 repression. Negative regulation of the p5 promoter requires the POZ domain, whereas viral replication is inhibited by the zinc finger domain, likely by competing with Rep for binding to the ITR. Identification and characterization of proteins that bind the ITR, the only viral genetic element retained in AAV2 vectors, will lead to new insights into the unique life cycle of AAV2 and will suggest improvements important for its application as a gene therapy vector.
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Affiliation(s)
- T Cathomen
- Laboratory of Genetics, The Salk Institute for Biological Studies, North Torrey Pines Road, La Jolla, CA 92037, USA
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5
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Abstract
Adeno-associated virus (AAV) vectors were shown capable of high efficiency transduction of both dividing and nondividing cells and tissues. AAV-mediated transduction leads to stable, long-term transgene expression in the absence of apparent immune response. These properties and the broad host range of AAV vectors indicate that they constitute a powerful tool for gene therapy purposes. An additional potential benefit of AAV vectors is their ability to integrate site-specifically in the presence of Rep proteins which can be expressed transiently, thus limiting their suspected adverse effects. The major restrictions of AAV as vectors are their limited genetic capacity and strict packaging size constraint of less than 5 kb. Another difficulty is the labor-intensive and expensive procedure for the production and packaging of recombinant AAV vectors. The major benefits and drawbacks of AAV vectors and advances made in the past 3 years are discussed.
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Affiliation(s)
- J Tal
- Department of Virology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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6
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Wollscheid V, Frey M, Zentgraf H, Sczakiel G. Purification and characterization of an active form of the p78Rep protein of adeno-associated virus type 2 expressed in Escherichia coli. Protein Expr Purif 1997; 11:241-9. [PMID: 9425627 DOI: 10.1006/prep.1997.0789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The 78-kDa product (p78Rep) of the rep gene of AAV-2 was expressed with an amino-terminal histidine-tag in Escherichia coli and was purified under denaturing conditions. After renaturation of the p78Rep protein by serial steps of dialysis, the biochemical activities of the p78Rep protein were demonstrated, which include the ATP-dependent endonuclease and helicase activity as well as sequence-specific binding to the AAV-2 terminal repeat. These activities were retained when the protein was purified under denaturing conditions followed by renaturation. When compared with published data for p68Rep, the helicase activity of p78Rep was stronger and the endonuclease activity was weaker. The p78Rep protein was able to inhibit HIV-1 replication after co-microinjection together with infectious proviral HIV-1 DNA into the nuclei of human cells, suggesting that p78Rep is necessary for inhibition of HIV-1 in vivo.
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Affiliation(s)
- V Wollscheid
- Forschungsschwerpunkt Angewandte Tumorvirologie, Deutsches Krebsforschungszentrum, Heidelberg, Federal Republic of Germany
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7
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Affiliation(s)
- J P Trempe
- Department of Biochemistry and Molecular Biology, Medical College of Ohio, Toledo 43699, USA
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8
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Yang Q, Chen F, Trempe JP. Characterization of cell lines that inducibly express the adeno-associated virus Rep proteins. J Virol 1994; 68:4847-56. [PMID: 8035483 PMCID: PMC236424 DOI: 10.1128/jvi.68.8.4847-4856.1994] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The replication (rep) gene of adeno-associated virus (AAV) is involved in AAV DNA replication, gene regulation, and inhibition of cellular transformation induced by various oncogenes. To study the rep gene's antiproliferative effects, we have developed cell lines which express the replication proteins under the control of an inducible mouse metallothionein transcription promoter. The Rep78 protein produced in these cell lines binds to the AAV terminal repeat sequences in vitro and supports AAV DNA replication and trans activation of the AAV p40 transcription promoter in vivo. These cell lines are capable of assembling infectious viruses containing a mutant rep gene or a vector bearing a heterologous gene. Growth rate and colony formation efficiency assays indicated that rep gene expression substantially altered cellular proliferation. Long-term induction of the cell lines followed by removal of the inducing agent suggested that constitutive expression of the Rep proteins does not necessarily result in cell death and that the cells can recover from the cytostatic effects. Flow cytometry analysis indicated that the presence of the Rep proteins increased the population of cells in the S phase of the cell cycle. Thus the rep gene's antiproliferative effects may be realized by interference with cellular DNA replication.
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Affiliation(s)
- Q Yang
- Department of Biochemistry and Molecular Biology, Medical College of Ohio, Toledo 43699-0008
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9
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Wu P, Ziska D, Bonell MA, Grouzmann E, Millard WJ, Meyer EM. Differential neuropeptide Y gene expression in post-mitotic versus dividing neuroblastoma cells driven by an adeno-associated virus vector. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1994; 24:27-33. [PMID: 7968366 DOI: 10.1016/0169-328x(94)90114-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The ability to express exogenous mammalian genes stably in post-mitotic cells such as neurons remains an important goal for those attempting to modulate neurotransmission through gene delivery. We therefore investigated how differentiation to a post-mitotic state affected the expression of an exogenous gene encoding for neuropeptide Y (NPY) following transfection with an adeno-associated virus (AAV) derived vector. This vector (pJDT95npy) was constructed with rat NPY cDNA (551 bp) inserted downstream from the indigenous AAV p5, p19 and p40 promoters to characterize their relative abilities to drive NPY mRNA expression. Transfection of dividing neuroblastoma CHP126 cells with pJDT95npy resulted in the differential expression of chimeric NPY mRNAs derived from each promoter. P40-driven species became dominant after 1 month post-transfection. Vector integration into chromosomal DNA was demonstrated by Southern blot analyses, indicating at least some region-selective integration. In dividing cell extracts, only a low level of pro-NPY immunoreactivity and no mature NPY immunoreactivity was recovered. However, after differentiation of the pJDT95npy-transfected CHP 126 cells to a post-mitotic state, significant levels of pro-NPY and mature NPY were recovered in the cells and media. Differentiation also had a time-dependent effect on mRNA expression: a spike of p5 driven expression on day 3 was followed predominantly by p40-driven expression on day 5. This study indicates that AAV-derived vectors using the p40 promoter may be used to express genes in post-mitotic cells such as neurons.
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Affiliation(s)
- P Wu
- Department of Pharmacology and Therapeutics, University of Florida College of Medicine, Gainesville 32610-0267
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10
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Leonard CJ, Berns KI. Adeno-associated virus type 2: a latent life cycle. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1994; 48:29-52. [PMID: 7938552 DOI: 10.1016/s0079-6603(08)60852-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- C J Leonard
- W. R. Hearst Microbiology Research Center, Department of Microbiology, Cornell University Medical College, New York, New York 10021
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11
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Abstract
Gene therapy for cystic fibrosis (CF) could potentially be accomplished with one of several recombinant virus vectors, including a murine retrovirus (MMuLV), adenovirus, or adeno-associated virus (AAV). All these vectors take advantage of their respective viruses' mechanisms for delivery of viral DNA to cells, evasion of lysosomal degradation, and optimization of the levels and duration of expression of viral (or vector) DNA. Each has its own unique life cycle, however. The differences among these viruses result in certain advantages and disadvantages, such as the requirement of retroviruses for active cell division, and the potential pathogenic effects from expression of certain adenovirus genes present in adenovectors. While no single vector may be optimal for CF gene therapy in humans, new techniques, such as receptor-mediated gene transfer, seek to take advantage of the desirable properties of one or more of the virus-based systems while avoiding certain potential hazards.
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Affiliation(s)
- T R Flotte
- Eudowood Division of Pediatric Respiratory Sciences, Johns Hopkins University School of Medicine, Johns Hopkins Hospital, Baltimore, Maryland 21205
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12
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Abstract
Adeno-associated virus is a human parvovirus that integrates its DNA genome into host cell chromosomes with very high efficiency. This suggests that adeno-associated virus may be a useful vector for human gene therapy. Interest in adeno-associated virus vectors increased greatly in the last year following reports that adeno-associated virus genome integration may be site specific and occur at preferred sites in the human genome. Several genes relevant to the treatment of genetic or infectious diseases have been expressed in adeno-associated virus vectors in vitro.
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Affiliation(s)
- B J Carter
- Targeted Genetics Corporation, Seattle, Washington
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13
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Winocour E, Puzis L, Etkin S, Koch T, Danovitch B, Mendelson E, Shaulian E, Karby S, Lavi S. Modulation of the cellular phenotype by integrated adeno-associated virus. Virology 1992; 190:316-29. [PMID: 1326806 DOI: 10.1016/0042-6822(92)91218-j] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The adeno-associated virus (AAV) rep gene encodes a series of overlapping, multifunctional, nonstructural proteins (Rep proteins) which regulate the viral life cycle and which are also capable of trans-regulating nonviral gene expressions (reviewed in Berns, 1990, Microbiol. Rev. 54, 316-329). To investigate the expression of the AAV rep gene in a cellular chromosomal context, SV40-transformed Chinese hamster embryo (OD4) cells were infected with an AAV/neo hybrid virus and progeny resistant to the antibiotic G418 were selected and amplified. Chromosomal integration and RNA transcription of the AAV and neo DNA inserts were confirmed by Southern and Northern blotting procedures. One of the G418R cell lines stably expressed a protein which reacted specifically with AAV anti-Rep antiserum in Western immunoblots. The stable integration of AAV rep DNA, which did not interfere with cell proliferation under normal growth conditions, was associated with two changes in cellular phenotype: eight of nine lines were markedly more sensitive to UV light (254 nm) than were the parental OD4 cells; and seven of the nine lines had lost the capacity to promote SV40 origin DNA amplification in vitro, in contrast to the parental OD4 cells. OD4 cells transformed to G418R by AAV/neo DNA constructs with a deleted rep gene, or by a neo DNA construct lacking AAV DNA, did not display these phenotypic changes. It is suggested that stable integration of the AAV rep gene interferes with cellular processes connected with DNA repair and gene amplification.
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Affiliation(s)
- E Winocour
- Department of Molecular Genetics and Virology, Weizmann Institute of Science, Rehovot, Israel
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14
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Flotte TR, Solow R, Owens RA, Afione S, Zeitlin PL, Carter BJ. Gene expression from adeno-associated virus vectors in airway epithelial cells. Am J Respir Cell Mol Biol 1992; 7:349-56. [PMID: 1325813 DOI: 10.1165/ajrcmb/7.3.349] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Lung diseases such as cystic fibrosis (CF) might be treated by gene therapy using viral vectors delivered to the airway. One potential vector is the defective human parvovirus, adeno-associated virus (AAV). We examined the AAV p5 transcription promoter for gene expression in immortalized cell lines derived from the airway (IB3-1) or pancreas (CFPAC-1) of CF patients. AAV vectors expressing the prokaryotic genes cat (pAAVp5cat) or neo (pAAVp5neo) from the p5 promoter were evaluated after introduction into IB3-1 or CFPAC-1 cells by lipofection. In transient assays in both cell lines, the cat gene was expressed 5- to 10-fold more efficiently from the p5 promoter than from a simian virus 40 early gene promoter (pSVcat). IB3-1 cells were transformed stably to geneticin resistance by pAAVp5neo at a 5-fold higher efficiency than by an SVneo vector. The AAV inverted terminal repeat (ITR) region immediately upstream of the p5 promoter appears to have an enhancer effect and the promoter also contains a CREB site which confers a response to forskolin. In IB3-1 cells, expression of the cat gene from a p5 promoter was decreased about 5-fold by deletion of both the upstream ITR and the CREB site. The AAVp5neo vector was also packaged into AAV particles and used to infect IB3-1 cells as a transducing virus. Under these conditions, 60 to 70% of the cells could be stably transformed to geneticin resistance. Thus, AAV transducing vectors appear to be a highly efficient delivery system for stable integration and expression of genes in cultured airway epithelial cells.
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Affiliation(s)
- T R Flotte
- Laboratory of Molecular and Cellular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
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15
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Walsh CE, Liu JM, Xiao X, Young NS, Nienhuis AW, Samulski RJ. Regulated high level expression of a human gamma-globin gene introduced into erythroid cells by an adeno-associated virus vector. Proc Natl Acad Sci U S A 1992; 89:7257-61. [PMID: 1323131 PMCID: PMC49685 DOI: 10.1073/pnas.89.15.7257] [Citation(s) in RCA: 146] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Gene therapy of severe hemoglobinopathies will require high-level expression of a transferred globin gene in erythroid cells. Distant regulatory elements flanking the beta-globin gene cluster, the locus control region, are needed for appropriate expression. We have explored the use of a human parvovirus, the adeno-associated virus (AAV), for globin gene transfer. The human A gamma-globin gene, linked to hypersensitivity site 2 from the locus control region of the beta-globin gene cluster, was subcloned into a plasmid (psub201) containing the AAV inverted terminal repeats. This construct was cotransfected with a helper plasmid containing trans-acting AAV genes into human 293 cells that had been infected with adenovirus. The recombinant AAV vector containing hypersensitivity site 2 stably introduced on average one or two unrearranged proviral copies into human K562 erythroleukemia cells. The transferred globin gene exhibited normal regulation upon hemin induction of erythroid maturation and was expressed at a level equivalent to a native chromosomal A gamma-globin gene.
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Affiliation(s)
- C E Walsh
- Clinical Hematology Branch, National Heart Lung and Blood Institute, Bethesda, MD 20892
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16
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Mendelson E, Grossman Z, Mileguir F, Rechavi G, Carter BJ. Replication of adeno-associated virus type 2 in human lymphocytic cells and interaction with HIV-1. Virology 1992; 187:453-63. [PMID: 1372138 DOI: 10.1016/0042-6822(92)90447-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Adeno-associated virus (AAV) is a nonpathogenic parvovirus which normally requires helper adenovirus or herpes-virus for replication. We examined the growth of AAV type 2 in human lymphocytes and its possible interaction with HIV-1. Three B cell lines (CK-B, HS-2, and UC729) and four T cell lines (Molt-4, Jurkat, HUT78, and HUT78+HIV, which is persistently infected with HIV-1) were infected with AAV either in the presence or in the absence of adenovirus. AAV DNA was found in cells of all the lines following incubation with the virus, indicating absorption. AAV DNA replication occurred in most cell lines without particular preference for B or T cells, but only in the presence of helper virus, either adenovirus or Epstein-Barr virus. Expression of AAV proteins was examined by immunoblotting and ELISA, using sera specific for AAV Rep or capsid proteins. The level of AAV protein synthesis correlated with the efficiency of AAV DNA replication, and both varied between cell lines. The yield of infectious AAV was low in most cases, except in one T4 line (Jurkat), where AAV replication and protein synthesis in the presence of adenovirus were very extensive. In HUT78+HIV cells both adenovirus and AAV (in the presence of Ad2) replicated efficiently. The effects of adenovirus plus AAV coinfections on HIV-1 replication, measured by reverse-transcriptase (RT) activity, were mild. Infection with adenovirus or AAV alone resulted in a 60-70% increase in RT activity, while infection with AAV plus adenovirus resulted in a 20% decrease in RT activity. The yield of infectious AAV in this cell line was very low.
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Affiliation(s)
- E Mendelson
- Central Virology Laboratory, Chaim Sheba Medical Center, Tel-Hashomer, Israel
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17
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Giraud C, Devauchelle G, Bergoin M. The densovirus of Junonia coenia (Jc DNV) as an insect cell expression vector. Virology 1992; 186:207-18. [PMID: 1530777 DOI: 10.1016/0042-6822(92)90075-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
An infectious genome of the Junonia coenia densovirus (Jc DNV) has been recently cloned and sequenced. We investigated the ability of this cloned genome to be used as expression vector by inserting the lacZ gene of Escherichia coli as fusion gene in the major open reading frame (ORF 1) of the viral sequence. The resulting recombinant plasmid designated pBRJlac Z was transfected into insect SPC-SL 52 cells and the expression of beta-galactosidase (beta-gal) was detected qualitatively or quantitatively by using Xgal or ONPG as chromogenic substrates. Western blot analysis revealed that beta-gal was expressed as chimeric capsid-beta-gal polypeptides. This provided evidence that ORF1 codes for structural polypeptides which share a common C-terminal sequence. Construction of plasmids with alterations or deletions in ORF2, 3 or 4, allowed us to implicate nonstructural (NS) functions in viral DNA replication. Deletions in inverted terminal repeats or in NS functions did not abolish expression of capsid polypeptides but reduced it dramatically. Encapsidation of Jlac Z recombinant genome was achieved by trans-complementation with plasmids bearing intact structural and nonstructural functions. Detection of a beta-gal activity in SPC-SL 52 cells following several subcultures post-transfection suggests that Jlac Z recombinant genome could be maintained in an integrative or episomal state.
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Affiliation(s)
- C Giraud
- Station de Recherches de Pathologie Comparée, INRA-UA CNRS, Saint Christol-lez-Alès, France
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18
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Muzyczka N. Use of adeno-associated virus as a general transduction vector for mammalian cells. Curr Top Microbiol Immunol 1992; 158:97-129. [PMID: 1316261 DOI: 10.1007/978-3-642-75608-5_5] [Citation(s) in RCA: 321] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- N Muzyczka
- Department of Microbiology, SUNY Stony Brook Medical School 11794
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19
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Antoni BA, Rabson AB, Miller IL, Trempe JP, Chejanovsky N, Carter BJ. Adeno-associated virus Rep protein inhibits human immunodeficiency virus type 1 production in human cells. J Virol 1991; 65:396-404. [PMID: 1845899 PMCID: PMC240530 DOI: 10.1128/jvi.65.1.396-404.1991] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The adeno-associated virus (AAV) rep gene encodes four proteins (Rep78, Rep68, Rep52, and Rep40) required for AAV DNA replication and AAV gene regulation. In addition, the Rep proteins may have pleiotropic regulatory effects in heterologous systems, and in particular Rep78 may mediate a negative regulatory effect. We analyzed the effects of the AAV rep gene on human immunodeficiency virus type 1 (HIV-1) gene expression. The rep gene proteins of AAV type 2 (AAV2) inhibited the trans-activating ability of HIV-1. Constructs containing the AAV2 rep gene (pHIVrep) or a CAT gene (pBennCAT) expressed from the 5' HIV-1 long terminal repeat were inducible for Rep78 and Rep68 or CAT expression, respectively, when cotransfected with a plasmid containing the HIV-1 tat gene (pARtat). When equivalent amounts of pHIVrep and pBennCAT were cotransfected with increasing amounts of pARtat, expression of CAT activity was decreased. The pHIVrep construct was more inhibitory than plasmids expressing rep from the wild-type AAV2 p5 transcription promoter. rep expression from pHIVrep almost completely inhibited the replication of an HIV-1 proviral clone as measured by reverse transcriptase activity and p24 protein levels. Inhibition of HIV-1 production by Rep protein was also seen at the transcriptional level in that all HIV-1 transcripts were decreased when pHIVrep was present. The inhibitory effects of pHIVrep appear to be mediated primarily by Rep78 and perhaps Rep68. These results suggest that a trans-acting protein from a heterologous virus might be used to inhibit HIV-1 growth.
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Affiliation(s)
- B A Antoni
- Laboratory of Molecular and Cellular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892
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20
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Abstract
The members of the family Parvoviridae are among the smallest of the DNA viruses, with a linear single-stranded genome of about 5 kilobases. Currently the family is divided into three genera, two of which contain viruses of vertebrates and a third containing insect viruses. This review concentrates on the vertebrate viruses, with emphasis on recent advances in our insights into the molecular biology of viral replication. Traditionally the vertebrate viruses have been distinguished by the presence or absence of a requirement for a coinfection with a helper virus before productive infection can occur, hence the notion that the dependoviruses (adeno-associated viruses [AAV]) are defective. Recent data would suggest that not only is there a great deal of structural and genetic organizational similarity between the two types of vertebrate viruses, but also there is significant similarity in the molecular biology of productive replication. What differs is the physiological condition of the host cell that renders it permissive. Healthy dividing cells are permissive for productive replication by autonomous parvoviruses; such cells result in latent infection by dependoviruses. For a cell to become permissive for productive AAV replication, it must have been exposed to toxic conditions which activate a latent AAV genome. Such conditions can be caused by helper-virus infection or exposure to physical (UV light) or chemical (some carcinogens) agents. In this paper the molecular biology of replication is reviewed, with special emphasis on the role of the host and the consequences of viral infection for the host.
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Affiliation(s)
- K I Berns
- Department of Microbiology, Hearst Microbiology Research Center, Cornell University Medical College, New York, New York 10021
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21
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Brandenburger A, Legendre D, Avalosse B, Rommelaere J. NS-1 and NS-2 proteins may act synergistically in the cytopathogenicity of parvovirus MVMp. Virology 1990; 174:576-84. [PMID: 2137660 DOI: 10.1016/0042-6822(90)90110-d] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The interaction of parvovirus minute virus of mice (prototype strain, MVMp) with simian virus 40 (SV40)-transformed human cells (NB-E) was investigated by means of transfection with MVMp molecular clones derived from the infectious recombinant plasmid (pMM984). pMM984 inhibits stable transformation of NB-E cells to geneticin resistance (G418R) upon cotransfection with the selectable pSV2neo plasmid. We show here that this inhibition is not merely caused by a repression of marker gene expression from the SV40 early region promoter in pSV2neo and rather is likely to reflect the cytotoxic action of the parvovirus. Starting from plasmid pMM984, defined mutations were introduced into the genome of MVMp and more particularly into sequences coding for the NS-1 and/or NS-2 nonstructural proteins. In this way we could show that the NS-1 protein is necessary for the inhibition of transformation to G418R and that the NS-2 protein acts synergistically to enhance this effect. Moreover, results obtained with different viral mutants indicate that the inhibitory action of NS-1 on stable transformation can be dissociated from the ability of this protein both to transactivate the parvoviral p39 promoter of the capsid protein-encoding region and to drive parvoviral DNA amplification. Altogether these data point to a probable direct toxicity of MVMp nonstructural proteins for permissive host cells.
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Affiliation(s)
- A Brandenburger
- Department of Molecular Biology, Université libre de Bruxelles, Rhode St Genèse, Belgium
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