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Rescue of Infectious Sindbis Virus by Yeast Spheroplast-Mammalian Cell Fusion. Viruses 2021; 13:v13040603. [PMID: 33916100 PMCID: PMC8066160 DOI: 10.3390/v13040603] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 03/26/2021] [Accepted: 03/29/2021] [Indexed: 12/13/2022] Open
Abstract
Sindbis virus (SINV), a positive-sense single stranded RNA virus that causes mild symptoms in humans, is transmitted by mosquito bites. SINV reverse genetics have many implications, not only in understanding alphavirus transmission, replication cycle, and virus-host interactions, but also in biotechnology and biomedical applications. The rescue of SINV infectious particles is usually achieved by transfecting susceptible cells (BHK-21) with SINV-infectious mRNA genomes generated from cDNA constructed via in vitro translation (IVT). That procedure is time consuming, costly, and relies heavily on reagent quality. Here, we constructed a novel infectious SINV cDNA construct that expresses its genomic RNA in yeast cells controlled by galactose induction. Using spheroplasts made from this yeast, we established a robust polyethylene glycol-mediated yeast: BHK-21 fusion protocol to rescue infectious SINV particles. Our approach is timesaving and utilizes common lab reagents for SINV rescue. It could be a useful tool for the rescue of large single strand RNA viruses, such as SARS-CoV-2.
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2
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Lundstrom K. Alphavirus vectors as tools in neuroscience and gene therapy. Virus Res 2015; 216:16-25. [PMID: 26307195 DOI: 10.1016/j.virusres.2015.08.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 08/17/2015] [Accepted: 08/19/2015] [Indexed: 11/30/2022]
Abstract
Alphavirus-based vectors have been engineered for in vitro and in vivo expression of heterelogous genes. The rapid and easy generation of replication-deficient recombinant particles and the broad range of host cell infection have made alphaviruses attractive vehicles for applications in neuroscience and gene therapy. Efficient delivery to primary neurons and hippocampal slices has allowed localization studies of gene expression and electrophysiological recordings of ion channels. Alphavirus vectors have also been applied for in vivo delivery to rodent brain. Due to the strong local transient expression provided by alphavirus vectors a number of immunization and gene therapy approaches have demonstrated both therapeutic and prophylactic efficacy in various animal models.
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Aranda A, Bezunartea J, Casales E, Rodriguez-Madoz JR, Larrea E, Prieto J, Smerdou C. A quick and efficient method to generate mammalian stable cell lines based on a novel inducible alphavirus DNA/RNA layered system. Cell Mol Life Sci 2014; 71:4637-51. [PMID: 24794511 PMCID: PMC11113970 DOI: 10.1007/s00018-014-1631-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/15/2014] [Accepted: 04/17/2014] [Indexed: 01/05/2023]
Abstract
We report a new method to generate high-expressing mammalian cell lines in a quick and efficient way. For that purpose, we developed a master cell line (MCL) containing an inducible alphavirus vector expressing GFP integrated into the genome. In the MCL, recombinant RNA levels increased >4,600-fold after induction, due to a doxycycline-dependent RNA amplification loop. The MCL maintained inducibility and expression during 50 passages, being more efficient for protein expression than a conventional cell line. To generate new cell lines, mutant LoxP sites were inserted into the MCL, allowing transgene and selection gene exchange by Cre-directed recombination, leading to quick generation of inducible cell lines expressing proteins of therapeutic interest, like human cardiotrophin-1 and oncostatin-M at several mg/l/24 h. These proteins contained posttranslational modifications, showed bioactivity, and were efficiently purified. Remarkably, this system allowed production of toxic proteins, like oncostatin-M, since cells able to express it could be grown to the desired amount before induction. These cell lines were easily adapted to growth in suspension, making this methodology very attractive for therapeutic protein production.
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Affiliation(s)
- Alejandro Aranda
- 3P Biopharmaceuticals S.L., Polígono Mocholí, C/Mocholí 2, 31110 Noain, Spain
- Division of Hepatology and Gene Therapy, Center for Applied Medical Research, University of Navarra, Pamplona, Navarra Spain
- Present Address: UFR des Sciences de la Santé Simone Veil, 2 Avenue de la Source de la Bievre, 78180 Montigny-Le-Bretonneux, France
| | - Jaione Bezunartea
- 3P Biopharmaceuticals S.L., Polígono Mocholí, C/Mocholí 2, 31110 Noain, Spain
| | - Erkuden Casales
- Division of Hepatology and Gene Therapy, Center for Applied Medical Research, University of Navarra, Pamplona, Navarra Spain
| | - Juan R. Rodriguez-Madoz
- Division of Hepatology and Gene Therapy, Center for Applied Medical Research, University of Navarra, Pamplona, Navarra Spain
| | - Esther Larrea
- Division of Hepatology and Gene Therapy, Center for Applied Medical Research, University of Navarra, Pamplona, Navarra Spain
| | - Jesus Prieto
- Division of Hepatology and Gene Therapy, Center for Applied Medical Research, University of Navarra, Pamplona, Navarra Spain
- Liver Unit, Clinica Universitaria de Navarra, CIBER-EHD, Pamplona, Spain
| | - Cristian Smerdou
- Division of Hepatology and Gene Therapy, Center for Applied Medical Research, University of Navarra, Pamplona, Navarra Spain
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4
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Guo TC, Johansson DX, Liljeström P, Evensen Ø, Haugland Ø. Modification of a salmonid alphavirus replicon vector for enhanced expression of heterologous antigens. J Gen Virol 2014; 96:565-570. [PMID: 25395591 DOI: 10.1099/vir.0.067348-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
A salmonid alphavirus (SAV) replicon has been developed to express heterologous antigens but protein production was low to modest compared with terrestrial alphavirus replicons. In this study, we have compared several modifications to a SAV replicon construct and analysed their influence on foreign gene expression. We found that an insertion of a translational enhancer consisting of the N-terminal 102 nt of the capsid gene, together with a nucleotide sequence encoding the foot-and-mouth disease virus (FMDV) 2A peptide, caused a significant increase in EGFP reporter gene expression. The importance of fusing a hammerhead (HH) ribozyme sequence at the 5' end of the viral genome was also demonstrated. In contrast, a hepatitis D virus ribozyme (HDV-RZ) sequence placed at the 3' end did not augment expression of inserted genes. Taken together, we have developed a platform for optimized antigen production, which can be applied for immunization of salmonid fish in the future.
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Affiliation(s)
- Tz-Chun Guo
- Norwegian University of Life Sciences, Department of Basic Sciences and Aquatic Medicine, P.O. Box 8146 Dep., N-0033 Oslo, Norway
| | - Daniel X Johansson
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Peter Liljeström
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Øystein Evensen
- Norwegian University of Life Sciences, Department of Basic Sciences and Aquatic Medicine, P.O. Box 8146 Dep., N-0033 Oslo, Norway
| | - Øyvind Haugland
- Norwegian University of Life Sciences, Department of Basic Sciences and Aquatic Medicine, P.O. Box 8146 Dep., N-0033 Oslo, Norway
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5
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Casales E, Aranda A, Quetglas JI, Ruiz-Guillen M, Rodriguez-Madoz JR, Prieto J, Smerdou C. A novel system for the production of high levels of functional human therapeutic proteins in stable cells with a Semliki Forest virus noncytopathic vector. N Biotechnol 2010; 27:138-48. [PMID: 20188220 DOI: 10.1016/j.nbt.2010.02.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Revised: 02/15/2010] [Accepted: 02/17/2010] [Indexed: 01/18/2023]
Abstract
Semliki Forest virus (SFV) vectors lead to high protein expression in mammalian cells, but expression is transient due to vector cytopathic effects, inhibition of host cell proteins and RNA-based expression. We have used a noncytopathic SFV mutant (ncSFV) RNA vector to generate stable cell lines expressing two human therapeutic proteins: insulin-like growth factor I (IGF-I) and cardiotrophin-1 (CT-1). Therapeutic genes were fused at the carboxy-terminal end of Puromycin N-acetyl-transferase gene by using as a linker the sequence coding for foot-and-mouth disease virus (FMDV) 2A autoprotease. These cassettes were cloned into the ncSFV vector. Recombinant ncSFV vectors allowed rapid and efficient selection of stable BHK cell lines with puromycin. These cells expressed IGF-I and CT-1 in supernatants at levels reaching 1.4 and 8.6 microg/10(6)cells/24 hours, respectively. Two cell lines generated with each vector were passaged ten times during 30 days, showing constant levels of protein expression. Recombinant proteins expressed at different passages were functional by in vitro signaling assays. Stability at RNA level was unexpectedly high, showing a very low mutation rate in the CT-1 sequence, which did not increase at high passages. CT-1 was efficiently purified from supernatants of ncSFV cell lines, obtaining a yield of approximately 2mg/L/24 hours. These results indicate that the ncSFV vector has a great potential for the production of recombinant proteins in mammalian cells.
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Affiliation(s)
- Erkuden Casales
- Center for Applied Medical Research, University of Navarra, Pamplona, Spain
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6
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Nivitchanyong T, Tsai YC, Betenbaugh MJ, Oyler GA. An improved in vitro and in vivo Sindbis virus expression system through host and virus engineering. Virus Res 2009; 141:1-12. [PMID: 19200810 DOI: 10.1016/j.virusres.2008.12.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2008] [Revised: 12/06/2008] [Accepted: 12/12/2008] [Indexed: 10/21/2022]
Abstract
The Sindbis viral expression system enables the rapid production of high levels of recombinant protein in mammalian cells; however, this expression is typically limited to transient production due to the cytotoxicity of the virus. Limiting the lethality inherent in the Sindbis virus vector in order to enable long term, sustained expression of recombinant proteins may be possible. In this study, modifications to virus and host have been combined in order to reduce the cytopathic effects. Non-cytopathic replication competent viruses of two Sindbis viral strains, TE and 633, were developed using a non-structural protein (nsP) P726S point mutation in order to obtain persistent heterologous gene expression in infected Baby Hamster Kidney (BHK) cells and Chinese Hamster Ovary (CHO) cells. Cells infected with the P726S variant viruses were able to recover after infection, while cells infected with normal virus died within 3 days. The P726S mutation did not reduce the susceptibility of 5- and 14-day-old mice to 633 and TE viruses in vivo. In addition, animal survival with the P726S variant viruses was increased and GFP expression was sustained for at least 14 days while the 633 and TE infection resulted in short-term GFP expression or an earlier mortality. Modifications to the host BHK and CHO cells themselves were subsequently undertaken by including the anti-apoptotic gene Bcl-2 and a deletion mutant of Bcl-2 (Bcl-2Delta) as another method for limiting the cytopathic effects of the Sindbis virus. The inclusion of anti-apoptotic genes permitted higher production of heterologous GFP protein following Sindbis virus infection, and the combination of the TE-P726S virus and the CHO-Bcl-2Delta cell line showed the greatest improvement in cell survival. Sindbis virus infection also induced ER stress in mammalian cells as detected by increased PERK phosphorylation and ATF4 translation. Overexpression of Parkin, an E3 ubiquitin ligase that can protect cells against agents that induce ER stress, suppressed Sindbis virus-induced cell death in both BHK cells and in vivo studies in mice. Such findings show that viral and host modifications can improve cell survival and production of heterologous proteins, change viral behavior in vitro and in vivo, and assist in the development of new expression or gene delivery vehicles.
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Affiliation(s)
- Toey Nivitchanyong
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, United States.
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7
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Hardy RW, Rice CM. Requirements at the 3' end of the sindbis virus genome for efficient synthesis of minus-strand RNA. J Virol 2005; 79:4630-9. [PMID: 15795249 PMCID: PMC1069581 DOI: 10.1128/jvi.79.8.4630-4639.2005] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2004] [Accepted: 12/03/2004] [Indexed: 11/20/2022] Open
Abstract
The 3'-untranslated region of the Sindbis virus genome is 0.3 kb in length with a 19-nucleotide conserved sequence element (3' CSE) immediately preceding the 3'-poly(A) tail. The 3' CSE and poly(A) tail have been assumed to constitute the core promoter for minus-strand RNA synthesis during genome replication; however, their involvement in this process has not been formally demonstrated. Utilizing both in vitro and in vivo analyses, we have examined the role of these elements in the initiation of minus-strand RNA synthesis. The major findings of this study with regard to efficient minus-strand RNA synthesis are the following: (i) the wild-type 3' CSE and the poly(A) tail are required, (ii) the poly(A) tail must be a minimum of 11 to 12 residues in length and immediately follow the 3' CSE, (iii) deletion or substitution of the 3' 13 nucleotides of the 3' CSE severely inhibits minus-strand RNA synthesis, (iv) templates possessing non-wild-type 3' sequences previously demonstrated to support virus replication do not program efficient RNA synthesis, and (v) insertion of uridylate residues between the poly(A) tail and a non-wild-type 3' sequence can restore promoter function to a limited extent. This study shows that the optimal structure of the 3' component of the minus-strand promoter is the wild-type 3' CSE followed a poly(A) tail of at least 11 residues. Our findings also show that insertion of nontemplated bases can restore function to an inactive promoter.
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Affiliation(s)
- Richard W Hardy
- Department of Biology, Indiana University, 1001 E. Third St., Bloomington, IN 47405, USA.
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8
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Miller MA, Lavine CL, Klas SD, Pfeffer LM, Whitt MA. Recombinant replication-restricted VSV as an expression vector for murine cytokines. Protein Expr Purif 2004; 33:92-103. [PMID: 14680966 DOI: 10.1016/j.pep.2003.08.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2003] [Revised: 08/11/2003] [Indexed: 11/29/2022]
Abstract
Vesicular stomatitis virus (VSV) is a prototypic non-segmented, negative-strand RNA virus that rapidly and efficiently shuts down the production of host cell-encoded proteins and utilizes the cell's protein production machinery to express high levels of virally encoded proteins. In an effort to take advantage of this characteristic of VSV, we have employed a reverse genetics system to create recombinant forms of VSV encoding a variety of murine cytokines. Previous studies have revealed that cells infected with recombinant VSV that lack expression of the surface glycoprotein (G protein), designated deltaG-VSV, more efficiently express and secrete recombinant proteins than do recombinant "wild-type" VSV. Therefore, murine cytokine-expressing recombinants were produced as deltaG viruses. Propagation of these deltaG viruses in cells that transiently express G protein in vitro results in G-complemented virions that can infect cells, shut down host protein synthesis, and express at high levels each virally encoded protein (including the designated cytokine). We assessed the ability of each deltaG-VSV construct to express recombinant cytokine by infecting BHK cells and then monitoring/measuring the production of the desired cytokine. When possible, the bioactivity of the cytokine products was also measured. The results presented here reveal that large quantities of bioactive cytokines can be produced rapidly and inexpensively using deltaG-VSV as a protein expression system.
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Affiliation(s)
- Mark A Miller
- Department of Molecular Sciences, University of Tennessee Health Science Center, 858 Madison Avenue, Memphis, TN 38163, USA.
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9
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Boorsma M, Hoenke S, Marrero A, Fischer R, Bailey JE, Renner WA, Bachmann MF. Bioprocess applications of a Sindbis virus-based temperature-inducible expression system. Biotechnol Bioeng 2002; 79:602-9. [PMID: 12209807 DOI: 10.1002/bit.10311] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The production and study of toxic proteins requires inducible expression systems with low basal level expression and high inducibility. Here, we describe bioprocess applications of the pCytTS temperature-regulatable Sindbis virus replicon-based expression system. We used green fluorescent protein as a marker protein to optimize the selection of stable transfected clones with increased expression levels. Using the optimized protocol, clones were constructed that produced the growth-inhibiting, anti-viral protein interferon beta (beta-IFN). Selected clones were analyzed for temperature-dependent beta-IFN production in adherent and suspension cultures in serum free medium. Specific expression levels were around 1.0 x 10(5) IU/10(6) cells/day (0.5 microg/10(6) cells/day) in suspension cultures and over 1.5 x 10(6) IU/mL/day (7.5 microg/mL/day) in hollow fiber reactors using adherent cells. Hexahistidine-tagged beta-IFN purified from T-flask cultures was highly glycosylated and showed high specific activity. beta-IFN mRNA amplified by the viral replicase for 10 days did not show an accumulation of mutations. These data suggest the applicability of the pCytTS-inducible expression system for the production of high-quality glycoproteins in different reactors.
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Affiliation(s)
- M Boorsma
- Cytos Biotechnology AG, Wagistrasse 21, CH-8952, Zurich-Schlieren, Switzerland
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10
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Boorsma M, Koller D, Renner WA, Bachmann MF. New applications of alphavirus-based expression vectors. Cytotechnology 2001; 35:203-12. [PMID: 22358860 PMCID: PMC3449701 DOI: 10.1023/a:1013192017048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Alphaviruses are positive stranded RNA viruses that replicate to extremely high titers. Sindbis and Semliki Forest viral vectors are widely used tools for high-level production of recombinant proteins. Recent studies have broadened their scope to vaccine production, gene therapy, and analysis of cell function. Here we discuss the development of non-cytopathic and inducible expression vectors which can be applied to bioprocess development strategies. Furthermore, a Sindbis-based expression cloning system has been developed that allows for the rapid identification of genes encoding proteins with a selected functional activity.
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Affiliation(s)
- Marco Boorsma
- Cytos Biotechnology AG, Wagistrasse 21, CH-8952 Zurich-Schlieren, Switzerland
- Institute for Biotechnology, ETH-Zurich, CH-8093 Zurich, Switzerland
| | - Daniel Koller
- Cytos Biotechnology AG, Wagistrasse 21, CH-8952 Zurich-Schlieren, Switzerland
| | - Wolfgang A. Renner
- Cytos Biotechnology AG, Wagistrasse 21, CH-8952 Zurich-Schlieren, Switzerland
| | - Martin F. Bachmann
- Cytos Biotechnology AG, Wagistrasse 21, CH-8952 Zurich-Schlieren, Switzerland
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11
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Affiliation(s)
- S Schlesinger
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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12
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Abstract
Alphaviruses are RNA enveloped viruses that are proving their value as expression vectors. They are particularly well-suited for this role as they are easily and quickly engineered and can be used to produce high levels of proteins of interest. A promising and important use is as vaccines against disease-causing agents such as HIV. The three alphaviruses now serving as vectors are Sindbis virus, Semliki Forest virus (SFV) and Venezuelan equine encephalitis (VEE) virus. Sindbis virus and SFV are well-known models for studies in molecular and cell biology; VEE virus is a human pathogen and had received some previous notoriety as a potential biological weapon. It is now becoming a potentially valuable vaccine vector. All three viruses are being tested as vaccines but, at present, only Sindbis virus and SFV have been considered for other uses. Sindbis virus vectors have been developed to screen libraries for the identification of new proteins and to devise sensitive assays to detect viruses more difficult to grow in culture. Both Sindbis virus and SFV vectors are serving as tools for fundamental studies in biology, examples include development in insects and analysis of protein functions in neuronal cells. In this article the replication strategy of alphaviruses and the different ways they can be engineered to serve as expression vectors is described. This provides an introduction to the ways these vectors have been used and illustrates the promise these vectors offer.
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Affiliation(s)
- S Schlesinger
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110-1093, USA.
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Todd S, Anderson C, Jolly DJ, Craik CS. HIV protease as a target for retrovirus vector-mediated gene therapy. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1477:168-88. [PMID: 10708857 DOI: 10.1016/s0167-4838(99)00272-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The dimeric aspartyl protease of HIV has been the subject of intense research for almost a decade. Knowledge of the substrate specificity and catalytic mechanism of this enzyme initially guided the development of several potent peptidomimetic small molecule inhibitors. More recently, the solution of the HIV protease structure led to the structure-based design of improved peptidomimetic and non-peptidomimetic antiviral compounds. Despite the qualified success of these inhibitors, the high mutation rate associated with RNA viruses continues to hamper the long-term clinical efficacy of HIV protease inhibitors. The dimeric nature of the viral protease has been conducive to the investigation of dominant-negative inhibitors of the enzyme. Some of these inhibitors are defective protease monomers that interact with functional monomers to form inactive protease heterodimers. An advantage of macromolecular inhibitors as compared to small-molecule inhibitors is the increased surface area of interaction between the inhibitor and the target gene product. Point mutations that preserve enzyme activity but confer resistance to small-molecule inhibitors are less likely to have an adverse effect on macromolecular interactions. The use of efficient retrovirus vectors has facilitated the delivery of these macromolecular inhibitors to primary human lymphocytes. The vector-transduced cells were less susceptible to HIV infection in vitro, and showed similar levels of protection compared to other macromolecular inhibitors of HIV replication, such as RevM10. These preliminary results encourage the further development of dominant-negative HIV protease inhibitors as a gene therapy-based antiviral strategy.
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Affiliation(s)
- S Todd
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94143-0446, USA.
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14
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Abstract
Alphavirus expression vectors are finding novel uses in research. They are showing increasing promise as vaccines and are being developed for diagnostic assays of other viruses. Some highlights over the past couple of years include improvements in packaging of replicons, targeting of Sindbis virus replicons, stable cell lines that can be induced to produce replicons, and the isolation of noncytopathic variants of Sindbis virus replicons. Reports that alphavirus vectors can efficiently infect neurons in rat hippocampal slices should increase their use in neurobiological studies.
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Affiliation(s)
- S Schlesinger
- Box 8230 Department of Molecular Microbiology Washington University School of Medicine 660 South Euclid Ave, St. Louis, MO 63110-1093, USA
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Frolov I, Agapov E, Hoffman TA, Prágai BM, Lippa M, Schlesinger S, Rice CM. Selection of RNA replicons capable of persistent noncytopathic replication in mammalian cells. J Virol 1999; 73:3854-65. [PMID: 10196280 PMCID: PMC104163 DOI: 10.1128/jvi.73.5.3854-3865.1999] [Citation(s) in RCA: 147] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The natural life cycle of alphaviruses, a group of plus-strand RNA viruses, involves transmission to vertebrate hosts via mosquitoes. Chronic infections are established in mosquitoes (and usually in mosquito cell cultures), but infection of susceptible vertebrate cells typically results in rapid shutoff of host mRNA translation and cell death. Using engineered Sindbis virus RNA replicons expressing puromycin acetyltransferase as a dominant selectable marker, we identified mutations allowing persistent, noncytopathic replication in BHK-21 cells. Two of these adaptive mutations involved single-amino-acid substitutions in the C-terminal portion of nsP2, the viral helicase-protease. At one of these loci, nsP2 position 726, numerous substitution mutations were created and characterized in the context of RNA replicons and infectious virus. Our results suggest a direct correlation between the level of viral RNA replication and cytopathogenicity. This work also provides a series of alphavirus replicons for noncytopathic gene expression studies (E. V. Agapov, I. Frolov, B. D. Lindenbach, B. M. Prágai, S. Schlesinger, and C. M. Rice, Proc. Natl. Acad. Sci. USA 95:12989-12994, 1998) and a general strategy for selecting RNA viral mutants adapted to different cellular environments.
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Affiliation(s)
- I Frolov
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110-1093, USA
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16
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Wurm F, Bernard A. Large-scale transient expression in mammalian cells for recombinant protein production. Curr Opin Biotechnol 1999; 10:156-9. [PMID: 10209142 DOI: 10.1016/s0958-1669(99)80027-5] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Large-scale transient expression from mammalian cells is a new technology. Breakthroughs have been achieved for non-viral delivery methods: transfections can now be done at the 1-10 L scale with mammalian cells grown in suspension. Production of 1-20 mg/L of recombinant protein have been obtained in stirred bioreactors. Modified alphaviruses have provided a fast and efficient expression technology based on viral vectors.
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Affiliation(s)
- F Wurm
- Ecole Polytechnique Federale de Lausanne, 1015 Lausanne, Switzerland
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17
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Abstract
The broad host range and superior infectivity of alphaviruses have encouraged the development of efficient expression vectors for Semliki Forest virus (SFV) and Sindbis virus (SIN). The generation of high-titer recombinant alphavirus stocks has allowed high-level expression of a multitude of nuclear, cytoplasmic, membrane-associated and secreted proteins in a variety of different cell lines and primary cell cultures. Despite the viral cytopathogenic effects, functional assays on recombinant proteins are possible for a time-period of at least 24 hours post-infection. The high percentage (80-95%) of primary neurons infected with SFV has allowed localization and functional studies of recombinant proteins in these primary cell cultures. Through multiple infection studies the interaction of receptor and G protein subunits has become feasible. Establishment of efficient scale-up procedures has allowed production of large quantities of recombinant protein. Potential gene therapy applications of alphaviruses could be demonstrated by injection of recombinant SIN particles expressing beta-galactosidase into mouse brain. Tissue/cell specific infection has been achieved by introduction of an IgG-binding domain of protein A domain into one of the spike proteins of SIN. This enabled efficient targeting of infection to human lymphoblastoid cells.
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Affiliation(s)
- K Lundstrom
- F. Hoffman-La Roche, Research Laboratories, Basel, Switzerland
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18
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Monastyrskaia K, Goepfert F, Hochstrasser R, Acuña G, Leighton J, Pink JR, Lundstrom K. Expression and intracellular localisation of odorant receptors in mammalian cell lines using Semliki Forest virus vectors. J Recept Signal Transduct Res 1999; 19:687-701. [PMID: 10071793 DOI: 10.3109/10799899909036680] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Odorant receptors are members of the G protein-coupled receptor superfamily. They are expressed on the surface of cilia of olfactory neurons, where they bind ligand (odorant). Studies of the molecular mechanisms of olfaction are complicated by the extremely large number of receptor genes, and difficulties in pairing a particular mammalian receptor to a specific odorant ligand in vivo. Here we report expression and localisation studies of two rat odorant receptor genes (17 and OR5), and C. elegans odr-10, using the Semliki Forest virus (SFV) system. All receptors were epitope-tagged at the N- or C-terminus in order to facilitate their detection in infected cells, and determine the localisation and membrane-orientation of recombinant proteins. The immortalised mouse olfactory neuronal cell line OLF 442, rat cortical and striatal primary neuron cultures, and the baby hamster kidney (BHK) cells, were infected and tested. Immunofluorescence and confocal microscopy studies performed on permeabilised, non-permeabilised and native cells revealed that in BHK cells the rat receptors 17 and OR5 were not targeted to the plasma membrane and remained in the endoplasmic reticulum. In contrast, in the mouse olfactory cell line OLF 442 both rat receptors were correctly inserted into the plasma membrane. Similar results were obtained using primary neurons, indicating that like mature neurons, the immortalised OLF 442 cells are capable of providing for correct odorant receptor processing and targeting.
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Nelson DM, Wahlfors JJ, Chen L, Onodera M, Morgan RA. Characterization of diverse viral vector preparations, using a simple and rapid whole-virion dot-blot method. Hum Gene Ther 1998; 9:2401-5. [PMID: 9829539 DOI: 10.1089/hum.1998.9.16-2401] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A number of different viruses have been adapted as gene transfer vectors, including retroviruses, adenoviruses, adenoassociated viruses (AAVs), herpes simplex virus, SV40 viruses, and alphaviruses (both Semliki Forest and Sindbis viruses). One of the major rate-limiting and time-consuming steps in the characterization of these vectors is the process of determining the viral vector titers. In addition, there is no "universal" method that can be used to rapidly estimate the titer and the utility of viral vector preparations. We demonstrate here that supernatant from diverse classes of viral vectors, with either RNA or DNA genomes, can be rapidly evaluated by a simple virus dot-blot hybridization without prior extraction of nucleic acids. This system can provide a reliable screen for physical titer of viral vector supernatants in 1 day.
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Affiliation(s)
- D M Nelson
- Clinical Gene Therapy Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-1851, USA
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Mills A. Receptor targets in William Tell country: insights into receptor biology using fluorescent proteins. Trends Pharmacol Sci 1998; 19:305-7. [PMID: 9745356 DOI: 10.1016/s0165-6147(98)01233-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- A Mills
- Receptor Pharmacology Unit, GlaxoWellcome Medicines Research Centre, Stevenage, UK
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Abstract
Rapid progress has been made with the molecular design of novel viral and non-viral gene therapy vectors. Exploiting upstream processes of producer cell-culture and downstream operations adapted from protein recovery, vectors have been accumulated in quantities and purities appropriate for the initiation of clinical trials. It is not clear, however, if such methodologies will be appropriate for efficient operation at the manufacturing scales required for clinically successful vectors. Technologies suited to the fractionation of nanoparticles may bypass practical bottlenecks experienced by current processes. The behaviour in such fractionation systems of natural and synthetic particles, which variously mimic the size, density and surface chemistry of vector products, could benefit the improved design of efficient manufacture for gene therapy vectors.
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Affiliation(s)
- A Lyddiatt
- Centre for Bioprocess Engineering, School of Chemical Engineering, University of Birmingham, UK.
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