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Jäger N, Pöhlmann S, Rodnina MV, Ayyub SA. Interferon-Stimulated Genes that Target Retrovirus Translation. Viruses 2024; 16:933. [PMID: 38932225 PMCID: PMC11209297 DOI: 10.3390/v16060933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 05/27/2024] [Accepted: 06/01/2024] [Indexed: 06/28/2024] Open
Abstract
The innate immune system, particularly the interferon (IFN) system, constitutes the initial line of defense against viral infections. IFN signaling induces the expression of interferon-stimulated genes (ISGs), and their products frequently restrict viral infection. Retroviruses like the human immunodeficiency viruses and the human T-lymphotropic viruses cause severe human diseases and are targeted by ISG-encoded proteins. Here, we discuss ISGs that inhibit the translation of retroviral mRNAs and thereby retrovirus propagation. The Schlafen proteins degrade cellular tRNAs and rRNAs needed for translation. Zinc Finger Antiviral Protein and RNA-activated protein kinase inhibit translation initiation factors, and Shiftless suppresses translation recoding essential for the expression of retroviral enzymes. We outline common mechanisms that underlie the antiviral activity of multifunctional ISGs and discuss potential antiretroviral therapeutic approaches based on the mode of action of these ISGs.
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Affiliation(s)
- Niklas Jäger
- Infection Biology Unit, German Primate Center—Leibniz Institute for Primate Research, 37077 Göttingen, Germany; (N.J.); (S.P.)
- Faculty of Biology and Psychology, University Göttingen, 37073 Göttingen, Germany
| | - Stefan Pöhlmann
- Infection Biology Unit, German Primate Center—Leibniz Institute for Primate Research, 37077 Göttingen, Germany; (N.J.); (S.P.)
- Faculty of Biology and Psychology, University Göttingen, 37073 Göttingen, Germany
| | - Marina V. Rodnina
- Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany;
| | - Shreya Ahana Ayyub
- Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany;
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Bandeira VS, Tomás HA, Alici E, Carrondo MJ, Coroadinha AS. Disclosing the Parameters Leading to High Productivity of Retroviral Producer Cells Lines: Evaluating Random Versus Targeted Integration. Hum Gene Ther Methods 2017; 28:78-90. [DOI: 10.1089/hgtb.2016.149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Affiliation(s)
- Vanessa S. Bandeira
- Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Hélio A. Tomás
- Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Evren Alici
- Cell and Gene Therapy Group, Center for Hematology and Regenerative Medicine, Department of Medicine, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Manuel J.T. Carrondo
- Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
- Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
| | - Ana S. Coroadinha
- Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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3
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Determinants of Moloney murine leukemia virus Gag-Pol and genomic RNA proportions. J Virol 2014; 88:7267-75. [PMID: 24741085 DOI: 10.1128/jvi.03513-13] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The Moloney murine leukemia virus (MoMLV) ribonucleoprotein complex is composed of an approximately 20:1 mixture of Gag and Gag-Pol polyproteins plus a single genomic RNA (gRNA) dimer. The mechanisms that regulate these proportions are unknown. Here, we examined whether virion proportions of Gag, Gag-Pol, and gRNA were determined by sampling (that is, if they reflected expression ratios or intracellular concentrations) or more specific recruitment. To this end, MoMLV Gag, Gag-Pol, and gRNA were expressed separately or together in various ratios. Varying the expression ratios of Gag and Gag-Pol revealed that Gag-Pol incorporation was stochastic and that the conserved 20:1 Gag/Gag-Pol ratio coincided with maximal particle production. When skewed expression ratios resulted in excess Gag-Pol, the released virions maintained the intracellular Gag/Gag-Pol ratios and the infectivity per virion was largely maintained, but virion production decreased sharply with high levels of Gag-Pol. The determinants of gRNA proportions were addressed by manipulating the amounts and contexts of functional nucleocapsid (NC) and the ratios of Gag to gRNA. The results showed that the NC domain of either Gag or Gag-Pol could provide gRNA packaging functions equally well. Unlike Gag-Pol, gRNA incorporation was saturable. An upper limit of gRNA incorporation was observed, and particle production was not disrupted by excess gRNA expression. These results indicate that the determinants of Gag/Gag-Pol proportions differ from those for Gag/gRNA. On the basis of the assumption that MoMLV evolved to produce virion components in optimal proportions, these data provide a means of estimating the proportion of unspliced MoMLV RNA that serves as genomic RNA. IMPORTANCE Viruses assemble their progeny from within the cells that they parasitize, where they must sort through a rich milieu of host proteins and nucleic acids to gather together their own building blocks, which are also proteins and nucleic acids. The research described here addresses whether or not the proportions of viral proteins and nucleic acids that are brought together to form a retroviral particle are determined by random sampling from the cell-and thus dictated by the components' availabilities within the cell-or if the amounts of each molecule are specified by the virus replication process. The results indicated that protein components of the murine retrovirus studied here are recruited by chance but that a specific counting mechanism defines the amount of nucleic acid incorporated into each progeny virion.
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Jääskeläinen M, Chang W, Moisy C, Schulman AH. Retrotransposon BARE displays strong tissue-specific differences in expression. THE NEW PHYTOLOGIST 2013; 200:1000-8. [PMID: 24033286 DOI: 10.1111/nph.12470] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 07/30/2013] [Indexed: 05/25/2023]
Abstract
The BARE retrotransposon comprises c. 10% of the barley (Hordeum vulgare) genome. It is actively transcribed, translated and forms virus-like particles (VLPs). For retrotransposons, the inheritance of new copies depends critically on where in the plant replication occurs. In order to shed light on the replication strategy of BARE in the plant, we have used immunolocalization and in situ hybridization to examine expression of the BARE capsid protein, Gag, at a tissue-specific level. Gag is expressed in provascular tissues and highly localized in companion cells surrounding the phloem sieve tubes in mature vascular tissues. BARE Gag and RNA was not seen in the shoot apical meristem of young seedlings, but appeared, following transition to flowering, in the developing floral spike. Moreover, Gag has a highly specific localization in pre-fertilization ovaries. The strong presence of Gag in the floral meristems suggests that newly replicated copies there will be passed to the next generation. BARE expression patterns are consistent with transcriptional regulation by predicted response elements in the BARE promoter, and in the ovary with release from epigenetic transcriptional silencing. To our knowledge, this is the first analysis of the expression of native retrotransposon proteins within a plant to be reported.
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Affiliation(s)
- Marko Jääskeläinen
- MTT/BI Plant Genomics Laboratory, Institute of Biotechnology, Viikki Biocenter, University of Helsinki, PO Box 65, Viikinkaari 1, FIN-00014, Helsinki, Finland
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5
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Focal Adhesion Proteins Talin-1 and Vinculin Negatively Affect Paxillin Phosphorylation and Limit Retroviral Infection. J Mol Biol 2011; 410:761-77. [DOI: 10.1016/j.jmb.2011.03.076] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 03/30/2011] [Accepted: 03/31/2011] [Indexed: 11/19/2022]
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Carrondo M, Panet A, Wirth D, Coroadinha AS, Cruz P, Falk H, Schucht R, Dupont F, Geny-Fiamma C, Merten OW, Hauser H. Integrated strategy for the production of therapeutic retroviral vectors. Hum Gene Ther 2011; 22:370-9. [PMID: 21043806 DOI: 10.1089/hum.2009.165] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2022] Open
Abstract
The broad application of retroviral vectors for gene delivery is still hampered by the difficulty to reproducibly establish high vector producer cell lines generating sufficient amounts of highly concentrated virus vector preparations of high quality. To enhance the process for producing clinically relevant retroviral vector preparations for therapeutic applications, we have integrated novel and state-of-the-art technologies in a process that allows rapid access to high-efficiency vector-producing cells and consistent production, purification, and storage of retroviral vectors. The process has been designed for various types of retroviral vectors for clinical application and to support a high-throughput process. New modular helper cell lines that permit rapid insertion of DNA encoding the therapeutic vector of interest at predetermined, optimal chromosomal loci were developed to facilitate stable and high vector production levels. Packaging cell lines, cultivation methods, and improved medium composition were coupled with vector purification and storage process strategies that yield maximal vector infectivity and stability. To facilitate GMP-grade vector production, standard of operation protocols were established. These processes were validated by production of retroviral vector lots that drive the expression of type VII collagen (Col7) for the treatment of a skin genetic disease, dystrophic epidermolysis bullosa. The potential efficacy of the Col7-expressing vectors was finally proven with newly developed systems, in particular in target primary keratinocyte cultures and three-dimensional skin tissues in organ culture.
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Affiliation(s)
- Manuel Carrondo
- Instituto de Biologia Experimental e Tecnológica/Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, P-2781-901 Oeiras, Portugal
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7
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Stewart HJ, Leroux-Carlucci MA, Sion CJM, Mitrophanous KA, Radcliffe PA. Development of inducible EIAV-based lentiviral vector packaging and producer cell lines. Gene Ther 2009; 16:805-14. [DOI: 10.1038/gt.2009.20] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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8
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Carrondo MJ, Merten OW, Haury M, Alves PM, Coroadinha AS. Impact of Retroviral Vector Components Stoichiometry on Packaging Cell Lines: Effects on Productivity and Vector Quality. Hum Gene Ther 2008; 19:199-210. [DOI: 10.1089/hum.2007.0101] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Manuel J.T. Carrondo
- Instituto de Biologia Experimental e Tecnológica/Instituto de Tecnologia Química e Biológica/Universidade Nova de Lisboa (IBET/ITQB/UNL), P-2781-901 Oeiras, Portugal
- Faculdade de Ciências e Tecnologia/Universidade Nova de Lisboa (FCT/UNL), P-2825 Monte da Caparica, Portugal
| | | | - Matthias Haury
- Gulbenkian Institute for Science, P-2780-156 Oeiras, Portugal
- EICAT, European Molecular Biology Laboratory (EMBL), D-69117 Heidelberg, Germany
| | - Paula M. Alves
- Instituto de Biologia Experimental e Tecnológica/Instituto de Tecnologia Química e Biológica/Universidade Nova de Lisboa (IBET/ITQB/UNL), P-2781-901 Oeiras, Portugal
| | - Ana S. Coroadinha
- Instituto de Biologia Experimental e Tecnológica/Instituto de Tecnologia Química e Biológica/Universidade Nova de Lisboa (IBET/ITQB/UNL), P-2781-901 Oeiras, Portugal
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Naghavi MH, Valente S, Hatziioannou T, de los Santos K, Wen Y, Mott C, Gundersen GG, Goff SP. Moesin regulates stable microtubule formation and limits retroviral infection in cultured cells. EMBO J 2006; 26:41-52. [PMID: 17170707 PMCID: PMC1782362 DOI: 10.1038/sj.emboj.7601475] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Accepted: 11/06/2006] [Indexed: 01/03/2023] Open
Abstract
In a functional screen of mammalian complementary DNA libraries, we identified moesin as a novel gene whose overexpression blocks infection by murine leukemia viruses and human immunodeficiency virus type 1 in human and rodent lines, before the initiation of reverse transcription. Knockdown of moesin by RNA interference resulted in enhanced infection, suggesting that even the endogenous basal levels of moesin in rat fibroblasts are sufficient to limit virus infection. Moesin acts as a crosslinker between plasma membrane and actin filaments, as well as a signal transducer in responses involving cytoskeletal remodeling. Moesin overexpression was found to downregulate the formation of stable microtubules, whereas knockdown of moesin increased stable microtubule formation. A virus-resistant mutant cell line also displayed decreased stable microtubule levels, and virus-sensitive revertants recovered from the mutant line showed restoration of the stable microtubules, suggesting that these cytoskeletal networks play an important role in early post-entry events in the retroviral lifecycle. Together, these results suggest that moesin negatively regulates stable microtubule networks and is a natural determinant of cellular sensitivity to retroviral infection.
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Affiliation(s)
- Mojgan H Naghavi
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Susana Valente
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | | | - Kenia de los Santos
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Ying Wen
- Department of Anatomy and Cell Biology, Columbia University, New York, NY, USA
| | - Christina Mott
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Gregg G Gundersen
- Department of Anatomy and Cell Biology, Columbia University, New York, NY, USA
| | - Stephen P Goff
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University, HHSC 1310, 701 West 168th Street, New York, NY 10032, USA. Tel.: +1 212 305 7956; Fax: +1 212 305 5106; E-mail:
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10
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Schucht R, Coroadinha AS, Zanta-Boussif MA, Verhoeyen E, Carrondo MJT, Hauser H, Wirth D. A New Generation of Retroviral Producer Cells: Predictable and Stable Virus Production by Flp-Mediated Site-Specific Integration of Retroviral Vectors. Mol Ther 2006; 14:285-92. [PMID: 16697259 DOI: 10.1016/j.ymthe.2005.12.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Revised: 12/09/2005] [Accepted: 12/13/2005] [Indexed: 11/18/2022] Open
Abstract
We developed a new strategy that provides well-defined high-titer producer cells for recombinant retroviruses in a minimum amount of time. The strategy involves the targeted integration of the retroviral vector into a chromosomal locus with favorable properties. For proof of concept we established a novel HEK293-based retroviral producer cell line, called Flp293A, with a single-copy retroviral vector integrated at a selected chromosomal locus. The vector was flanked by noninteracting Flp-recombinase recognition sites and was exchanged for different retroviral vectors via Flp-mediated cassette exchange. All analyzed cell clones showed correct integration and identical titers for each of the vectors, confirming that the expression characteristics from the parental cell were preserved. Titers up to 2.5 x 10(7) infectious particles/10(6) cells were obtained. Also, high-titer producer cells for a therapeutic vector that encodes the 8.9-kb collagen VII cDNA in a marker-free cassette were obtained within 3 weeks without screening. Thus, we provide evidence that the precise integration of viral vectors into a favorable chromosomal locus leads to high and predictable virus production. This method is compatible with other retroviral vectors, including self-inactivating vectors and marker-free vectors. Further, it provides a tool for evaluation of different retroviral vector designs.
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Affiliation(s)
- R Schucht
- Department of Gene Regulation and Differentiation, German Research Center for Biotechnology, D-38124 Braunschweig, Germany
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11
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Hotta A, Saito Y, Kyogoku K, Kawabe Y, Nishijima KI, Kamihira M, Iijima S. Characterization of transient expression system for retroviral vector production. J Biosci Bioeng 2006; 101:361-8. [PMID: 16716946 DOI: 10.1263/jbb.101.361] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2005] [Accepted: 01/31/2006] [Indexed: 12/19/2022]
Abstract
The production of retroviral vectors using a transient expression system has been improved to obtain a high-titer virus preparation that is difficult to produce using packaging cell lines due to the cytotoxic or cytostatic effect of transgenes. Here, we used one such production method, the so-called Q-vector system, and examined its potential for virus production. The Q-vector system could produce a similar level of viral vectors compared with the packaging cell system but the production seemed to depend on the size and nature of transgenes. In the process of investigation of the quantitative difference in viral components between the transient expression system and the packaging cell system, we found that the Q-vector system could express higher amounts of viral RNA and proteins compared with the packaging cell system. However, this did not lead to a higher virus titer compared with that produced by the packaging cell system. This suggests that retroviral RNA transcribed from the plasmid in the transient system seemed to be used mainly for translation and only some of the RNA molecules were packaged in viral particles.
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Affiliation(s)
- Akitsu Hotta
- Department of Biotechnology, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan
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12
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Coroadinha AS, Schucht R, Gama-Norton L, Wirth D, Hauser H, Carrondo MJT. The use of recombinase mediated cassette exchange in retroviral vector producer cell lines: predictability and efficiency by transgene exchange. J Biotechnol 2006; 124:457-68. [PMID: 16529836 DOI: 10.1016/j.jbiotec.2006.01.037] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Revised: 12/16/2005] [Accepted: 01/04/2006] [Indexed: 12/01/2022]
Abstract
Currently, retroviral vector producer cell lines must be established for the production of each gene vector. This is done by transfection of a packaging cell line with the gene of interest. In order to find a high-titer retroviral vector producer clone, exhaustive clone screening is necessary, as the random integration of the transgene gives rise to different expression levels. We established a virus producing packaging cell line, the 293 FLEX, in which the viral vector is flanked by two different FRT sites and a selection trap. Using Flp recombinase mediated cassette exchange; this vector can be replaced by another compatible retroviral vector. The first step was the tagging of 293 cells with a lacZ reporter gene, which allowed screening and choosing a high expressing chromosomal locus. After checking that, a single copy of the construct was integrated, cassette exchangeability was confirmed with a reporter targeting construct. Subsequently gag-pol and GaLV envelope genes were stably transfected. The lacZ transgene was replaced by a GFP transgene and the 293 FLEX producer cell line maintained the titer, thus validating the flexibility and efficacy of this producer cell line. The tagged retroviral producer cell clone should constitute a highly advantageous cell line since it has a predictable titer and can be rapidly used for different therapeutic applications.
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Affiliation(s)
- A S Coroadinha
- Instituto de Biologia Experimental e Tecnológica/Instituto de Tecnologia Química e Biológica (IBET/ITQB), Oeiras, Portugal
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Coroadinha AS, Ribeiro J, Roldão A, Cruz PE, Alves PM, Merten OW, Carrondo MJT. Effect of medium sugar source on the production of retroviral vectors for gene therapy. Biotechnol Bioeng 2006; 94:24-36. [PMID: 16514678 DOI: 10.1002/bit.20778] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The production of gene therapy retroviral vectors presents many difficulties, mainly due to vector instability and low cell productivities hampering the attainment of high titers of infectious viral vectors. The objective of this work is to increase the production titers of retroviral vectors by manipulating the sugar carbon sources used in bioreaction. Four sugars were tested (glucose, galactose, sorbitol, and fructose) on an established Moloney murine leukemia virus (MoMLV) producer cell line. Galactose and sorbitol did not support cell growth or vector production. Glucose supplemented at 25 mM supported the highest cell growth; however, the use of glucose or fructose at 83 and 140 mM have shown to improve the infectious vector titer three to fourfold. The reasons for the titer improvements were further analyzed and, although, the cell-specific productivity in viral transgene RNA and reverse transcriptase were augmented 5- and 6-fold for glucose at 140 mM and 14- and 16-fold for fructose at 140 mM, comparing with glucose at 25 mM, these increases did not seem sufficient to account for the 14- (140 mM glucose) and 32- (140 mM fructose) fold increment obtained for the infectious particles-specific productivity. Further accounting the enhancement in the titers was the improvement in the viral stability, the half-life of the vectors was enhanced by 30-60%. This resulted in a product quality with a superior ratio of infectious to total particles, thus reducing the most problematic contaminant in the production of retroviral vectors, non-infectious retroviral particles.
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Lei P, Andreadis ST. Stoichiometric limitations in assembly of active recombinant retrovirus. Biotechnol Bioeng 2005; 90:781-92. [PMID: 15812799 DOI: 10.1002/bit.20468] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although recombinant retroviruses are widely used in gene therapy and as gene transfer vehicles for basic biological studies, their titers are very low as compared to other recombinant viral systems, e.g., adenovirus. We investigated the rate-limiting steps in production of LacZ-encoding ecotropic (CRE BAG 2) and amphotropic (Psi-CRIP) retrovirus. We found that ecotropic retrovirus producer cells produced a large number of inactive viral particles because they were severely limited by the amount of mRNA that was packaged into viral capsids. Introduction of the gene for green fluorescence protein (GFP) increased retroviral titers 40-fold, without affecting the viral matrix protein, p30, or the activity of reverse transcriptase. Surprisingly, while transfer of GFP gene increased retrovirus production, beta-gal activity and X-gal titer decreased significantly. Quantitative real-time polymerase chain reaction (PCR) showed that although producer cells synthesized similar amounts of both mRNAs, retroviral supernatants contained significantly lower amount of LacZ mRNA, possibly due to competition between LacZ and GFP mRNAs for encapsidation into virions. In contrast to ecotropic producers, introduction of GFP gene copies into amphotropic producers resulted in a moderate twofold increase in retrovirus production. However, delivery of genes encoding for the viral proteins gp70 and p30 increased virus production by fivefold, suggesting that amphotropic producers may also be limited by synthesis of structural viral proteins. Our data show that in addition to the amount of viral genome or proteins, assembly of viral components into active viral particles may limit production of high titer retroviral preparations.
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Affiliation(s)
- Pedro Lei
- Bioengineering Laboratory, Department of Chemical and Biological Engineering, 908 Furnas Hall, University at Buffalo, The State University of New York, Amherst, New York 14260, USA
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15
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Chen Y, Miller WM, Aiyar A. Transduction efficiency of pantropic retroviral vectors is controlled by the envelope plasmid to vector plasmid ratio. Biotechnol Prog 2005; 21:274-82. [PMID: 15903266 PMCID: PMC2913131 DOI: 10.1021/bp049865x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pantropic retroviral vectors pseudotyped with vesicular stomatitis virus envelope G protein (VSV-G) are typically produced by transient transfection of the VSV-G expression plasmid because constitutive expression of VSV-G is cytotoxic. To produce pantropic vectors, the VSV-G expression plasmid and the vector plasmid are cotransfected into a packaging cell line, such as 293-gag-pol. Typically, the ratio of VSV-G plasmid to the vector plasmid ranges from 0.33 to 1.0. However, it is not clear that this range is optimal for vector production. In this study we have systematically examined the effect of the ratio of VSV-G plasmid (pVSV-G) to vector plasmid on vector production. For this, 293-gag-pol stable packaging cells were cotransfected with pVSV-G and an enhanced green fluorescent protein- (EGFP-) expressing retroviral vector plasmid (pLTR-EGFP) by use of lipofectamine. Vector was collected following transfection and used to transduce three target cell lines, namely, 3T3 fibroblasts, telomerase-immortalized human diploid fibroblasts (HDF), and the human hepatoma cell line HuH7. Transduction efficiency was evaluated for vectors produced at different pVSV-G:pLTR-EGFP ratios such that the total amount of plasmid transfected into 293-gag-pol cells was kept constant. Our results indicate that transduction efficiency is greatest when the pVSV-G:pLTR-EGFP ratio is substantially below 1.0. For 3T3 and HDF cells, the maximum transduction efficiency was obtained when a ratio of pVSV-G:pLTR-EGFP ranging from 0.053 to 0.2 was used for transfection. The relative magnitude of this effect was greater for lower transduction efficiencies in control cultures. For HuH7 cells, the beneficial effects were smaller than those observed when HDF or 3T3 cells were used. The difference in transduction efficiency for vector produced under various pVSV-G:pLTR-EGFP ratios was not due to differences in the proliferation of packaging cells or target cells. Further characterization showed that the amount of vector RNA relative to p30gag decreased as the ratio of pVSV-G:pLTR-EGFP increased. These results indicate that transduction efficiency increases with increasing levels of vector RNA as long as a minimally sufficient level of pantropic envelope protein is expressed.
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Affiliation(s)
| | | | - Ashok Aiyar
- To whom correspondence should be addressed. W.M.M. . A.A.
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Houzet L, Battini JL, Bernard E, Thibert V, Mougel M. A new retroelement constituted by a natural alternatively spliced RNA of murine replication-competent retroviruses. EMBO J 2003; 22:4866-75. [PMID: 12970198 PMCID: PMC212718 DOI: 10.1093/emboj/cdg450] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Replication of simple retroviruses depends on the recruitment of a single large primary transcript toward splicing, transport/packaging and translation regulations. In this respect, we studied the novel SD' 4.4 kb RNA of murine leukemia retroviruses (MLV) which results from alternative splicing of the primary transcript. We showed that SD' RNA was required for optimal replication since expression of a pre-spliced SD' RNA trans-complemented the impaired infectivity of a SD'-defective mutant. We monitored the fate of this novel transcript throughout early and late events of the viral life cycle. SD' RNA was specifically incorporated into virions demonstrating that the unspliced RNA was not the unique viral RNA present in virions. Furthermore, SD' RNA was reverse transcribed and its DNA copy integrated into the host genome, thus constituting a new splice donor-associated retroelement (SDARE) in infected cells. Finally, we showed that SD' mRNA encoded a 50 kDa polyprotein, and to a lower extent an additional 60 kDa polyprotein, which harbored Gag and integrase domains.
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Affiliation(s)
- Laurent Houzet
- Institut de Genetique Moleculaire, UMR5555 CNRS, Montpellier, 4 Boulevard Henri IV, CS89508, 34960 Montpellier, France
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Bajgelman MC, Costanzi-Strauss E, Strauss BE. Exploration of critical parameters for transient retrovirus production. J Biotechnol 2003; 103:97-106. [PMID: 12814868 DOI: 10.1016/s0168-1656(03)00103-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The pCL system was developed to aid in the production of retrovirus that encodes cytotoxic or cytostatic cDNA's. A principal feature of this system is the transient production of virus after co-transfection of the viral and packaging vectors in the 293T cell line. This approach obviates the need for selection of the producer cells, thus minimizing potential affects of the encoded genes. However, the transient nature of this system also creates a number of experimental variables. In this study we have examined and optimized elements related to the production of the pCL retrovirus. For example, co-transfection of the packaging sequence along with the viral vector has been optimized in terms of both the total amount of DNA transfected and the relative proportion of each plasmid. We have also tested the affect of increased synthesis of viral proteins in the producer cells and the kinetics of virus accumulation in the supernatant. These findings may be of interest to those who use pCL or any transient packaging system in their gene transfer studies. In addition, these studies may aid in the validation and development of transient retrovirus production systems for clinical applications.
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Affiliation(s)
- Marcio C Bajgelman
- Department of Histology and Embryology, Institute of Biomedical Sciences, University of São Paulo, SP, São Paulo, Brazil
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Rohll JB, Mitrophanous KA, Martin-Rendon E, Ellard FM, Radcliffe PA, Mazarakis ND, Kingsman SM. Design, production, safety, evaluation, and clinical applications of nonprimate lentiviral vectors. Methods Enzymol 2002; 346:466-500. [PMID: 11883086 DOI: 10.1016/s0076-6879(02)46072-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Affiliation(s)
- Jonathan B Rohll
- Department of Biochemistry, Oxford BioMedica (UK) Limited, Oxford OX4 4GA, United Kingdom
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