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Takeda A, Matano T. Inhibition of infectious murine leukemia virus production by Fv-4 env gene products exerting dominant negative effect on viral envelope glycoprotein. Microbes Infect 2007; 9:1590-6. [DOI: 10.1016/j.micinf.2007.09.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2007] [Revised: 09/07/2007] [Accepted: 09/09/2007] [Indexed: 11/28/2022]
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2
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Murphy SL, Chung-Landers M, Honczarenko M, Gaulton GN. Linkage of reduced receptor affinity and superinfection to pathogenesis of TR1.3 murine leukemia virus. J Virol 2006; 80:4601-9. [PMID: 16611920 PMCID: PMC1472024 DOI: 10.1128/jvi.80.9.4601-4609.2006] [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] [Indexed: 11/20/2022] Open
Abstract
TR1.3 is a Friend murine leukemia virus (MLV) that induces selective syncytium induction (SI) of brain capillary endothelial cells (BCEC), intracerebral hemorrhage, and death. Syncytium induction by TR1.3 has been mapped to a single tryptophan-to-glycine conversion at position 102 of the envelope glycoprotein (Env102). The mechanism of SI by TR1.3 was examined here in comparison to the non-syncytium-inducing, nonpathogenic MLV FB29, which displays an identical BCEC tropism. Envelope protein expression and stability on both infected cells and viral particles were not statistically different for TR1.3 and FB29. However, affinity measurements derived using purified envelope receptor binding domain (RBD) revealed a reduction of >1 log in the K(D) of TR1.3 RBD relative to FB29 RBD. Whole-virus particles pseudotyped with TR1.3 Env similarly displayed a markedly reduced binding avidity compared to FB29-pseudotyped viral particles. Lastly, decreased receptor affinity of TR1.3 Env correlated with the failure to block superinfection following acute and chronic infection by TR1.3. These results definitively show that acquisition of a SI phenotype can be directly linked to amino acid changes in retroviral Env that decrease receptor affinity, thereby emphasizing the importance of events downstream of receptor binding in the cell fusion process and pathology.
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Affiliation(s)
- Samuel L Murphy
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, 354 BRB II/III, 421 Curie Blvd., Philadelphia, Pennsylvania 19104-6142, USA
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3
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Ou W, Silver J. Inhibition of murine leukemia virus envelope protein (env) processing by intracellular expression of the env N-terminal heptad repeat region. J Virol 2005; 79:4782-92. [PMID: 15795264 PMCID: PMC1069576 DOI: 10.1128/jvi.79.8.4782-4792.2005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A conserved structural motif in the envelope proteins of several viruses consists of an N-terminal, alpha-helical, trimerization domain and a C-terminal region that refolds during fusion to bind the N-helix trimer. Interaction between the N and C regions is believed to pull viral and target membranes together in a crucial step during membrane fusion. For several viruses with type I fusion proteins, C regions pack as alpha-helices in the grooves between N-helix monomers, and exogenously added N- and C-region peptides block fusion by inhibiting the formation of the six-helix bundle. For other viruses, including influenza virus and murine leukemia virus (MLV), there is no evidence for comparably extended C-region alpha-helices, although a short, non-alpha-helical interaction structure has been reported for influenza virus. We tested candidate N-helix and C-region peptides from MLV for their ability to inhibit cell fusion but found no inhibitory activity. In contrast, intracellular expression of the MLV N-helix inhibited fusion by efficiently blocking proteolytic processing and intracellular transport of the envelope protein. The results highlight another mechanism by which the N-helix peptides can inhibit fusion.
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Affiliation(s)
- Wu Ou
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Building 4, Room 336, Bethesda, MD 20892, USA
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4
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Kano M, Matano T, Kato A, Nakamura H, Takeda A, Suzaki Y, Ami Y, Terao K, Nagai Y. Primary replication of a recombinant Sendai virus vector in macaques. J Gen Virol 2002; 83:1377-1386. [PMID: 12029153 DOI: 10.1099/0022-1317-83-6-1377] [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: 11/18/2022] Open
Abstract
An efficient antigen expression system using a recombinant Sendai virus (SeV) has been established recently and its potential to induce resistance against immunodeficiency virus infections in macaques has been shown. SeV replication has been well characterized in mice, the natural host, but not in primates, including humans. Here, primary SeV replication was investigated in macaques. After intranasal immunization with a recombinant SeV expressing simian immunodeficiency virus Gag protein, SeV-Gag, robust gag expression was observed in the nasal mucosa and much lower but significant levels of gag expression were observed in the local retropharyngeal and submandibular lymph nodes (LN). Expression peaked within a week and lasted at least up to 13 days after immunization. SeV-Gag was isolated from nasal swabs consistently at day 4 but not at all at day 13. Gag expression was undetectable in the lung as well as in remote lymphoid tissues, such as the thymus, spleen and inguinal LN, indicating that the spread of the virus was more restricted in macaques than in mice. SeV-specific T cells were detectable in SeV-immunized macaques at day 7. Finally, no naive macaques showed significant levels of anti-SeV antibodies in the plasma, even after living in a cage together with an acutely SeV-infected macaque for 5 weeks, indicating that SeV transmission from SeV-infected macaques to naive ones was inefficient. None of the SeV-immunized macaques displayed appreciable clinical manifestations. These results support the idea that this system may be used safely in primates, including humans.
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Affiliation(s)
- Munehide Kano
- AIDS Research Centre1, Department of Viral Diseases and Vaccine Control2 and Division of Experimental Animal Research3, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Tetsuro Matano
- Department of Microbiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan5
- AIDS Research Centre1, Department of Viral Diseases and Vaccine Control2 and Division of Experimental Animal Research3, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Atsushi Kato
- AIDS Research Centre1, Department of Viral Diseases and Vaccine Control2 and Division of Experimental Animal Research3, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Hiromi Nakamura
- AIDS Research Centre1, Department of Viral Diseases and Vaccine Control2 and Division of Experimental Animal Research3, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Akiko Takeda
- AIDS Research Centre1, Department of Viral Diseases and Vaccine Control2 and Division of Experimental Animal Research3, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Yuriko Suzaki
- AIDS Research Centre1, Department of Viral Diseases and Vaccine Control2 and Division of Experimental Animal Research3, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Yasushi Ami
- AIDS Research Centre1, Department of Viral Diseases and Vaccine Control2 and Division of Experimental Animal Research3, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Keiji Terao
- Tsukuba Primate Research Centre, National Institute of Infectious Diseases, 1 Hachimandai, Tsukuba 305-0843, Japan2
| | - Yoshiyuki Nagai
- Toyama Institute of Health, Nakataikou-yama 17-1, Kosugi-machi, Imizu-gun, Toyama 939-0363, Japan4
- AIDS Research Centre1, Department of Viral Diseases and Vaccine Control2 and Division of Experimental Animal Research3, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
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5
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Kitagawa M, Aizawa S, Sado T, Yamaguchi S, Suzuki T, Hirokawa K, Ikeda H. A gene therapy model for retrovirus-induced disease with a viral env gene: expression-dependent resistance in immunosuppressed hosts. Leukemia 2001; 15:1779-84. [PMID: 11681421 DOI: 10.1038/sj.leu.2402279] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
At the initial stage of retroviral infection, virion envelope glycoprotein (env product) binds to cell surface receptors. Cells infected with retrovirus or into which the env gene was introduced, become resistant to superinfection by other retroviruses with the same receptor specificity, a phenomenon known as receptor interference. We have demonstrated previously that the introduction of an env gene from a truncated endogenous ecotropic murine leukemia virus (MuLV), the Fv-4 resistance (Fv-4r) gene, into the bone marrow hematopoietic cells of Fv-4 sensitive (Fv-4s) mice protected mice from ecotropic retrovirus-induced disease. Using the gene transfer system under the control of the retroviral vector and bone marrow transplantation (BMT), here we could show that the expression of an introduced Fv-4r gene in hematopoietic cells continued for more than 1 year after BMT. To determine the inhibitory mechanism of Fv-4r env gene expression against FLV-infection in this model system, peripheral blood mononuclear cells (PBMCs), or spleen cells from chimeras with various degrees of env-expression, were mixed with green fluorescence protein (GFP)-conjugated Friend MuLV envglycoprotein (GFP-Fr-ENV). The amount of GFP-Fr-ENV bound to these cells inversely correlated with the expression intensity of the transduced env gene indicating the receptor interference effect. Next, to see whether transduction of the Fv-4r gene would protect an immunosuppressed host from FLV-induced leukemogenesis, we generated immunocompromised chimeras by transplanting env-transduced bone marrow cells into a thymectomized host. These chimeras also resisted FLV-induced leukemogenesis, indicating that receptor interference-based gene therapy could become a therapeutic basis for immunodeficiency virus-induced diseases in vivo.
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Affiliation(s)
- M Kitagawa
- Department of Pathology and Immunology, Aging and Developmental Sciences, Tokyo Medical and Dental University, Graduate School, Japan
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Yap MW, Kingsman SM, Kingsman AJ. Effects of stoichiometry of retroviral components on virus production. J Gen Virol 2000; 81:2195-2202. [PMID: 10950977 DOI: 10.1099/0022-1317-81-9-2195] [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
A study was conducted to investigate the effects of increasing the amount of each retroviral component on vector production. It was found that, while the components of both amphotropic and ecotropic vectors were expressed independently of each other in a transient transfection system, increasing the amount of the gag/gag-pol component resulted in a decrease in virus titres for the amphotropic particles but not ecotropic particles. Analyses of the virus stocks produced indicated that the negative effect on titres was closely linked to the availability of envelope proteins for virion incorporation. The negative effect was not observed for ecotropic particle production in 293T cells, where the ecotropic receptor was absent, but was manifested when production was conducted in 293/12 cells expressing the ecotropic receptor. This suggested that the premature interaction between envelope and receptor in producer cells could limit the amount of envelope available for virion incorporation. In designing optimal vector production systems it is essential, therefore, to balance the concentration of the vector components and to ensure that there is never an excess of Gag/Gag-Pol.
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Affiliation(s)
- Melvyn W Yap
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK1
| | - Susan M Kingsman
- Oxford BioMedica (UK) Ltd, The Medawar Centre, The Oxford Science Park, Oxford OX4 4GA, UK2
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK1
| | - Alan J Kingsman
- Oxford BioMedica (UK) Ltd, The Medawar Centre, The Oxford Science Park, Oxford OX4 4GA, UK2
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK1
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7
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Matano T, Kano M, Odawara T, Nakamura H, Takeda A, Mori K, Sato T, Nagai Y. Induction of protective immunity against pathogenic simian immunodeficiency virus by a foreign receptor-dependent replication of an engineered avirulent virus. Vaccine 2000; 18:3310-8. [PMID: 10869776 DOI: 10.1016/s0264-410x(00)00122-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In AIDS vaccine strategies, live attenuated vaccines can confer good resistance against pathogenic virus infections but have the potential risk of inducing disease, whereas safer replication-negative strategies such as DNA vaccinations have so far failed to prevent the disease onset. Here, we developed a novel DNA vaccine strategy to induce restricted replication of an avirulent virus and evaluated it in a simian immunodeficiency virus (SIV) infection model. We generated a chimeric SIV, FMSIV, by replacing SIV env with ecotropic Friend murine leukemia virus (FMLV) env to confine its replication to FMLV receptor (mCAT1)-expressing cells. In primate cells lacking mCAT1, FMSIV did not replicate unless mCAT1 was introduced exogenously. Vaccination to macaques with both the FMSIV DNA and the mCAT1-expression plasmid DNA induced SIV Gag-specific cellular immune responses and resistance against pathogenic SIV(mac239) challenge more efficiently than the replication-negative control vaccination with the FMSIV DNA alone. This strategy may be useful for development of safe and effective vaccines against various kinds of pathogenic viruses.
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Affiliation(s)
- T Matano
- AIDS Research Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashi-murayama, 208-0011, Tokyo, Japan.
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8
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Ikeda H, Kato K, Suzuki T, Kitani H, Matsubara Y, Takase-Yoden S, Watanabe R, Kitagawa M, Aizawa S. Properties of the naturally occurring soluble surface glycoprotein of ecotropic murine leukemia virus: binding specificity and possible conformational change after binding to receptor. J Virol 2000; 74:1815-26. [PMID: 10644355 PMCID: PMC111660 DOI: 10.1128/jvi.74.4.1815-1826.2000] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Ecotropic murine leukemia virus (MuLV) infection is initiated by the interaction between the surface glycoprotein (SU) of the virus and its cell-surface receptor mCAT-1. We investigated the SU-receptor interaction by using a naturally occurring soluble SU which was encoded by the envelope (env) gene of a defective endogenous MuLV, Fv-4(r). Binding of the SU to mCAT-1-positive mouse cells was completed by 1 min at 37 degrees C. The SU could not bind to mouse cells that were persistently infected by ecotropic MuLVs (but not amphotropic or dualtropic MuLVs) or transfected with wild-type ecotropic env genes or a mutant env gene which can express only precursor Env protein that is restricted to retention in the endoplasmic reticulum. These cells were also resistant to superinfection by ecotropic MuLVs. Thus, superinfection resistance correlated with the lack of SU-binding capacity. After binding to the cells, the SU appeared to undergo some conformational changes within 1 min in a temperature-dependent manner. This was suggested by the different properties of two monoclonal antibodies (MAbs) reactive with the same C-terminal half of the Fv-4(r) SU domain, including a proline-rich motif which was shown to be important for conformation of the SU and interaction between the SU and the transmembrane protein. One MAb reacting with the soluble SU bound to cells was dissociated by a temperature shift from 4 to 37 degrees C. Such dissociation was not observed in cells synthesizing the SU or when another MAb was used, indicating that the dissociation was not due to a temperature-dependent release of the MAb but to possible conformational changes in the SU.
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Affiliation(s)
- H Ikeda
- National Institute of Animal Health, Tsukuba, Chiba, Japan.
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9
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BIOLOGICAL ROLE OF HGF/MET PATHWAY IN RENAL CELL CARCINOMA. J Urol 1999. [DOI: 10.1097/00005392-199903000-00076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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HORIE SHIGEO, ARUGA SEIJI, KAWAMATA HITOSHI, OKUI NOBUO, KAKIZOE TADAO, KITAMURA TADAICHI. BIOLOGICAL ROLE OF HGF/MET PATHWAY IN RENAL CELL CARCINOMA. J Urol 1999. [DOI: 10.1016/s0022-5347(01)61834-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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11
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Kitagawa M, Aizawa S, Kamisaku H, Hirokawa K, Ikeda H. Protection of retrovirus-induced disease by transplantation of bone marrow cells transduced with MuLV env gene via retrovirus vector. Exp Hematol 1999; 27:234-41. [PMID: 10029162 DOI: 10.1016/s0301-472x(98)00040-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Fv-4 is a mouse gene that dominantly confers resistance to infection by ecotropic murine leukemia virus (MuLV). We have demonstrated previously that bone marrow chimeras in which hematopoietic cells were replaced with cells expressing Fv-4 resistant (Fv-4r) gene product became refractory to Friend leukemia virus (FLV)-induced leukemogenesis. To induce in vivo resistance against retrovirus-induced diseases by retroviral vector-mediated gene transduction, we introduced Fv-4 env gene into bone marrow cells of FLV-susceptible C3H/He (C3H) mice with retroviral vector (pLSF) derived from murine Friend spleen focus forming virus (SFFV) and the cells were transplanted into lethally irradiated C3H mice. After the bone marrow transplantation, Fv-4r gene product was successfully expressed on erythroid and myeloid cells, while lymphoid cells were only weakly expressing Fv-4r gene product. The C3H mice expressing relatively higher amounts of Fv-4r gene product were rendered resistant to FLV-induced erythroleukemia, while mice expressing lower amounts of the Fv-4r gene product were still susceptible. Effective protection of FLV-induced leukemia in these mice suggested that the Fv-4r gene expression by erythroid cells that were the major target of FLV infection might be critical for resisting FLV-induced leukemia. Thus, gene therapy model by transducing Fv-4r env gene using bone marrow transplantation would provide a useful protection model system of retrovirus-induced diseases.
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Affiliation(s)
- M Kitagawa
- Department of Pathology and Immunology, Faculty of Medicine, Tokyo Medical and Dental University, Japan.
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12
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Lund OS, Losman B, Schønning K, Bolmstedt A, Olofsson S, Hansen JE. Inhibition of HIV type 1 infectivity by coexpression of a wild-type and a defective glycoprotein 120. AIDS Res Hum Retroviruses 1998; 14:1445-50. [PMID: 9824322 DOI: 10.1089/aid.1998.14.1445] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
An amino acid substitution (D --> K) in the C3 region of HIV-1 gp120 has previously been shown to inhibit binding of virions to CD4+ cells. We have introduced the same mutation into the HIV-1 isolate LAV-I(BRU), in which the mutation is denoted D373K. Here we show that the D373K envelope protein is processed and incorporated into virus particles, but that D373K virions have no detectable infectivity (below 0.1% relative to wild type). When D373K and the wild-type envelope gene were cotransfected in 293 cells at a 4:1 ratio, the resultant infectivity of the HIV-1 supernatant was reduced more than 100-fold. When the same ratio of plasmids was tested in COS-1 cells the inhibition of HIV-1 was an order of magnitude less than observed in 293 cells. COS-1 and 293 cells differed in that only 293 cells displayed saturation of virus production with respect to the envelope protein. Our data fit a simple model: when virion formation is saturated with envelope protein, expression and incorporation of a defective envelope protein imply a corresponding dilution of wild-type protein on the surface of virions. The cooperative function of wild-type envelope proteins is subsequently compromised, and a trans-dominant inhibition of virus infectivity is observed.
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Affiliation(s)
- O S Lund
- Laboratory for Infectious Diseases, Department 144, Hvidovre Hospital, Denmark
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Odawara T, Oshima M, Doi K, Iwamoto A, Yoshikura H. Threshold number of provirus copies required per cell for efficient virus production and interference in moloney murine leukemia virus-infected NIH 3T3 cells. J Virol 1998; 72:5414-24. [PMID: 9620996 PMCID: PMC110173 DOI: 10.1128/jvi.72.7.5414-5424.1998] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The gag-pol readthrough mutant of Moloney murine leukemia virus, MLV-B(CAG) (T. Odawara, H. Yoshikura, M. Oshima, T. Tanaka, D. S. Jones, F. Nemoto, Y. Kuchino, and A. Iwamoto, J. Virol. 65:6376-6379, 1991), was poorly complemented by a mutant encoding only Gag. This is because with all the genetic elements necessary for env expression present in MLV-B(CAG), insufficient Env protein was produced by the cells expressing MLV-B(CAG) for efficient virus production. Since the env mRNA expression per provirus in the MLV-B(CAG)- and wild-type-MLV-producing cells were the same and since the cells expressing the former contained eightfold fewer proviral copies, the insufficient Env expression by the former was found to be due to insufficient proviral copies in the cells. Examination of the cell clones having various proviral copies of Deltawt MLV (M. Oshima, T. Odawara, T. Matano, H. Sakahira, Y. Kuchino, A. Iwamoto, and H. Yoshikura, J. Virol. 70:2286-2295, 1996) showed that mRNA level was proportional to the number of proviral copies while interference and virus production followed a sigmoid curve with a sharp rise at the threshold number of proviral copies of around four per cell. Multicycle infection probably continues until the threshold level of proviral copies is attained in natural infection too.
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Affiliation(s)
- T Odawara
- Department of Bacteriology, Faculty of Medicine, University of Tokyo, Bunkyo-ku, Tokyo 113, Japan.
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Kitagawa M, Aizawa S, Ikeda H, Hirokawa K. Establishment of a therapeutic model for retroviral infection using the genetic resistance mechanism of the host. Pathol Int 1996; 46:719-25. [PMID: 8916140 DOI: 10.1111/j.1440-1827.1996.tb03540.x] [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: 02/03/2023]
Abstract
Resistance to retroviral infection is often regulated by multiple genes that control different aspects of the host-virus interaction. Genetically distinct inbred strains of mice differ in their susceptibility to retrovirus and have allowed the identification of several host-resistant loci that regulate the host defense mechanism to retroviral infection. Using the murine retrovirus infection system, a therapeutic model has been developed of retrovirus infection in association with the resistant mechanism of host genes. The most effective result achieved with the model was when using bone marrow transplantation of retrovirus-resistant cells with receptor interference function, which was genetically defined by the Fv-4 resistant gene. The possible application of these findings to the gene therapy of retrovirus-induced disease of humans is discussed.
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Affiliation(s)
- M Kitagawa
- Department of Pathology and Immunology, Faculty of Medicine, Tokyo Medical and Dental University, Japan
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15
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Burns CC, Poss ML, Thomas E, Overbaugh J. Mutations within a putative cysteine loop of the transmembrane protein of an attenuated immunodeficiency-inducing feline leukemia virus variant inhibit envelope protein processing. J Virol 1995; 69:2126-32. [PMID: 7884859 PMCID: PMC188879 DOI: 10.1128/jvi.69.4.2126-2132.1995] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
A replication-defective feline leukemia virus molecular clone, 61B, has been shown to cause immunodeficiency in cats and cytopathicity in T cells after a long latency period when coinfected with a minimally pathogenic helper virus (J. Overbaugh, E. A. Hoover, J. I. Mullins, D. P. W. Burns, L. Rudensey, S. L. Quackenbush, V. Stallard, and P. R. Donahue, Virology 188:558-569, 1992). The long-latency phenotype of 61B has been mapped to four mutations in the extracellular domain of the envelope transmembrane protein, and we report here that these mutations cause a defect in envelope protein processing. Immunoprecipitation analyses demonstrated that the 61B gp85 envelope precursor was produced but that further processing to generate the surface protein (SU/gp70) and the transmembrane protein (TM/p15E) did not occur. The 61B precursor was not expressed on the cell surface and appeared to be retained in the endoplasmic reticulum or Golgi apparatus. Two of the four 61B-specific amino acid changes are located within a putative cysteine loop in a region of TM that is conserved among retroviruses. Introduction of these two amino acid changes into a replication-competent highly cytopathic virus resulted in the production of noninfectious virus that exhibited an envelope-protein-processing defect. This analysis suggests that mutations in a conserved region within a putative cysteine loop affect retroviral envelope protein maturation and viral infectivity.
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Affiliation(s)
- C C Burns
- Department of Microbiology, University of Washington, Seattle 98195
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16
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Fujita K, Maldarelli F, Purcell DF, Silver J. Murine retroviral vector that induces long-term expression of HIV-1 envelope protein. J Virol Methods 1994; 50:293-311. [PMID: 7714053 DOI: 10.1016/0166-0934(94)90185-6] [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: 02/06/2023]
Abstract
A retroviral vector was constructed that induces long-term expression of human immunodeficiency virus type 1 (HIV-1) rev, vpu and env genes. The vector contains the neo gene and a cytomegalovirus (CMV) immediate early promoter followed by HIV-1 sequence. When HeLa cells were infected with viral stocks derived from this vector, about 25% of the resulting G418-resistant clones expressed HIV-1 envelope protein (Env), easily detectable by Western blot analysis, metabolic labelling, and syncytium formation after co-cultivation with HeLa-CD4 cells. In most cases the level of Env expression was higher than in a T cell line (H9) chronically infected with HIV-1. Env-expressing HeLa cell lines also expressed Rev, detected by transfection with a Rev-dependent CAT gene construct, and Vpu, detected by immunoprecipitation with a Vpu-specific antiserum. The 75% of G418-resistant HeLa cell lines that did not express Env were found to contain proviruses that had undergone deletion of env sequences corresponding to a known intron; presumably these cell lines arose as a result of infection with virions derived from spliced RNAs. This vector should be useful for studying non-transient effects of HIV Env, Rev and Vpu in tissue culture, and for the production of Env- and/or Rev-expressing cell lines.
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Affiliation(s)
- K Fujita
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
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17
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Matano T, Odawara T, Ohshima M, Iwamoto A, Yoshikura H. Interaction between the dominant negative mutant and the wild-type envelope proteins of Friend murine leukemia virus. J Virol 1994; 68:6079-82. [PMID: 8057486 PMCID: PMC237017 DOI: 10.1128/jvi.68.9.6079-6082.1994] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Interaction between the previously obtained dominant negative mutant, referred to as fcr (T. Matano, T. Odawara, M. Ohshima, H. Yoshikura, and A. Iwamoto, J. Virol. 67:2026-2033, 1993), and the wild-type envelope proteins (Env) of Friend murine leukemia virus was examined. The wild-type Env was bound to the fcr mutant Env and trapped in the endoplasmic reticulum. The virus receptor was not involved in this interaction.
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Affiliation(s)
- T Matano
- Department of Bacteriology, Faculty of Medicine, University of Tokyo, Japan
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Linder M, Wenzel V, Linder D, Stirm S. Structural elements in glycoprotein 70 from polytropic Friend mink cell focus-inducing virus and glycoprotein 71 from ecotropic Friend murine leukemia virus, as defined by disulfide-bonding pattern and limited proteolysis. J Virol 1994; 68:5133-41. [PMID: 8035513 PMCID: PMC236457 DOI: 10.1128/jvi.68.8.5133-5141.1994] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The disulfide-bonding pattern of glycoprotein 70 (gp70), the surface glycoprotein (SU) encoded by the envelope gene of polytropic Friend milk cell focus-inducing virus, was elucidated and compared with that of glycoprotein 71 (gp71), the corresponding glycoprotein of the ecotropic Friend murine leukemia virus, which had previously been determined (M. Linder, D. Linder, J. Hahnen, H.-H. Schott, and Stirm, Eur. J. Biochem. 203:65-73, 1992). In the carboxy-terminal constant domain, in which these glycoproteins have about 97% sequence homology, the location of the four disulfide bonds was found to be analogous. In the amino-terminal differential domain, with about 37% sequence homology, 8 of the 12 cysteine residues of the ecotropic SU are conserved in the polytropic SU. In this domain, a similar clustering of disulfide bonds was detected, which led to the identification of three distinct disulfide-bonded regions in both glycoproteins. However, because of deletions and sequence deviations, the glycoproteins must have significantly different three-dimensional structures in these regions. Since the receptor-binding functions of both glycoproteins have been attributed to their amino-terminal domains and since each binds to a different receptor, these disulfide-bonded structures are likely candidates for receptor-binding functions. Limited proteolysis of both glycoproteins with various endoproteinases led to the identification of preferential proteolytic sites between disulfide-bonded regions, at the beginning of the hypervariable proline-rich region, and between differential and constant domains, further confirming the structural organization of the folded glycoproteins.
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Affiliation(s)
- M Linder
- Biochemisches Institut am Klinikum, Justus-Liebig-Universität, Giessen, Germany
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