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Jennings J, Bracey H, Nguyen DT, Dasgupta R, Rivera AV, Sluis-Cremer N, Shi J, Aiken C. The HIV-1 capsid serves as a nanoscale reaction vessel for reverse transcription. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.08.566350. [PMID: 37986899 PMCID: PMC10659366 DOI: 10.1101/2023.11.08.566350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
The viral capsid performs critical functions during HIV-1 infection and is a validated target for antiviral therapy. Previous studies have established that the proper structure and stability of the capsid are required for efficient HIV-1 reverse transcription in target cells. Moreover, it has recently been demonstrated that permeabilized virions and purified HIV-1 cores undergo efficient reverse transcription in vitro when the capsid is stabilized by addition of the host cell metabolite inositol hexakisphosphate (IP6). However, the molecular mechanism by which the capsid promotes reverse transcription is undefined. Here we show that wild type HIV-1 particles can undergo efficient reverse transcription in vitro in the absence of a membrane-permeabilizing agent. This activity, originally termed "natural endogenous reverse transcription" (NERT), depends on expression of the viral envelope glycoprotein during virus assembly and its incorporation into virions. Truncation of the gp41 cytoplasmic tail markedly reduced NERT activity, indicating that gp41 permits the entry of nucleotides into virions. Protease treatment of virions markedly reduced NERT suggesting the presence of a proteinaceous membrane channel. By contrast to reverse transcription in permeabilized virions, NERT required neither the addition of IP6 nor a mature capsid, indicating that an intact viral membrane can substitute for the function of the viral capsid during reverse transcription in vitro. Collectively, these results demonstrate that the viral capsid functions as a nanoscale container for reverse transcription during HIV-1 infection.
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Affiliation(s)
- Jordan Jennings
- Department of Pathology, Microbiology, and Immunology and Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Harrison Bracey
- Department of Pathology, Microbiology, and Immunology and Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Danny T. Nguyen
- Department of Pathology, Microbiology, and Immunology and Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Rishav Dasgupta
- Department of Pathology, Microbiology, and Immunology and Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Alondra Vázquez Rivera
- Division of Infectious Disease, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Nicolas Sluis-Cremer
- Division of Infectious Disease, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, United States of America
| | - Jiong Shi
- Department of Pathology, Microbiology, and Immunology and Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Christopher Aiken
- Department of Pathology, Microbiology, and Immunology and Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
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2
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Aiken C, Rousso I. The HIV-1 capsid and reverse transcription. Retrovirology 2021; 18:29. [PMID: 34563203 PMCID: PMC8466977 DOI: 10.1186/s12977-021-00566-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 07/20/2021] [Indexed: 02/08/2023] Open
Abstract
The viral capsid plays a key role in HIV-1 reverse transcription. Recent studies have demonstrated that the small molecule IP6 dramatically enhances reverse transcription in vitro by stabilizing the viral capsid. Reverse transcription results in marked changes in the biophysical properties of the capsid, ultimately resulting in its breakage and disassembly. Here we review the research leading to these advances and describe hypotheses for capsid-dependent HIV-1 reverse transcription and a model for reverse transcription-primed HIV-1 uncoating.
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Affiliation(s)
- Christopher Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Itay Rousso
- Department of Physiology and Cell Biology, Ben-Gurion University of the Negev, Beer Sheva, Israel
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3
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Sivakumaran H, Cutillas V, Harrich D. Revisiting transdominant-negative proteins in HIV gene therapy. Future Virol 2013. [DOI: 10.2217/fvl.13.65] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
HIV remains a global public health issue and new therapies are actively being developed. Traditional treatments such as small-molecule inhibitors are being investigated; however, newer modalities are also being pursued, including the use of transdominant-negative proteins. A transdominant negative is a mutant of a protein designed to interfere with the normal activity of its wild-type counterpart. Transdominant negatives designed to block HIV replication are based on viral proteins; however, recent approaches show that transdominant negatives of cellular proteins have therapeutic potential. Recent discoveries have revealed that treatments based on transdominant negatives can greatly disrupt the replication cycle of the virus. This article aims to review viral and cellular protein-based transdominant negatives, the recent elucidation of their modes of action and their potential use in HIV gene therapy.
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Affiliation(s)
- Haran Sivakumaran
- Queensland Institute of Medical Research, Molecular Virology Laboratory, 300 Herston Road, Herston, Brisbane, 4006, Australia
| | - Vincent Cutillas
- Queensland Institute of Medical Research, Molecular Virology Laboratory, 300 Herston Road, Herston, Brisbane, 4006, Australia
| | - David Harrich
- Queensland Institute of Medical Research, Molecular Virology Laboratory, 300 Herston Road, Herston, Brisbane, 4006, Australia
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4
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Apolloni A, Lin MH, Sivakumaran H, Li D, Kershaw MHR, Harrich D. A mutant Tat protein provides strong protection from HIV-1 infection in human CD4+ T cells. Hum Gene Ther 2013; 24:270-82. [PMID: 23298160 DOI: 10.1089/hum.2012.176] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Here we show potent inhibition of HIV-1 replication in a human T cell line and primary human CD4(+) cells by expressing a single antiviral protein. Nullbasic is a mutant form of the HIV-1 Tat protein that was previously shown to strongly inhibit HIV-1 replication in nonhematopoietic cell lines by targeting three steps of HIV-1 replication: reverse transcription, transport of viral mRNA, and trans-activation of HIV-1 gene expression. Here we investigated gene delivery of Nullbasic, using lentiviral and retroviral vectors. Although Nullbasic could be delivered by lentiviral vectors to target cells, transduction efficiencies were sharply reduced primarily because of negative effects on reverse transcription mediated by Nullbasic. However, Nullbasic did not inhibit transduction of HEK293T cells by a murine leukemia virus (MLV)-based retroviral vector. Therefore, MLV-based virus-like particles were used to transduce and express Nullbasic-EGFP or EGFP in Jurkat cells, a human leukemia T cell line, and Nullbasic-ZsGreen1 or ZsGreen1 in primary human CD4(+) cells. HIV-1 replication kinetics were similar in parental Jurkat and Jurkat-EGFP cells, but were strongly attenuated in Jurkat-Nullbasic-EGFP cells. Similarly, virus replication in primary CD4(+) cells expressing a Nullbasic-ZsGreen1 fusion protein was inhibited by approximately 8- to 10-fold. These experiments demonstrate the potential of Nullbasic, which has unique inhibitory activity, as an antiviral agent against HIV-1 infection.
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Affiliation(s)
- Ann Apolloni
- Queensland Institute of Medical Research, Molecular Virology Laboratory, Herston, Brisbane, Queensland 4006, Australia
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5
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A strongly transdominant mutation in the human immunodeficiency virus type 1 gag gene defines an Achilles heel in the virus life cycle. J Virol 2009; 83:8536-43. [PMID: 19515760 DOI: 10.1128/jvi.00317-09] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) protease (PR) makes five obligatory cleavages in the viral Gag polyprotein precursor. The cleavage events release the virion structural proteins from the precursor and allow the virion to undergo maturation to become infectious. The protease cleavage between the matrix protein (MA) domain and the adjacent capsid protein (CA) domain releases CA from the membrane-anchored MA and allows the N terminus of CA to refold into a structure that facilitates the formation of hexamer arrays that represent the structural unit of the capsid shell. In this study, we analyzed the extent to which each of the HIV-1 Gag processing sites must be cleaved by substituting the P1-position amino acid at each processing site with Ile. A mutation that blocks cleavage at the MA/CA processing site (Y132I) displayed a strong transdominant effect when tested in a phenotypic mixing strategy, inhibiting virion infectivity with a 50% inhibitory concentration of only 4% of the mutant relative to the wild type. This mutation is 10- to 20-fold more potent in phenotypic mixing than an inactivating mutation in the viral protease, the target of many successful inhibitors, and more potent than an inactivating mutation at any of the other Gag cleavage sites. The transdominant effect is manifested as the assembly of an aberrant virion core. Virus containing 20% of the Y132I mutant and 80% of the wild type (to assess the transdominant effect on infectivity) was blocked either before reverse transcription (RT) or at an early RT step. The ability of a small amount of the MA/CA fusion protein to poison the oligomeric assembly of infectious virus identifies an essential step in the complex process of virion formation and maturation. The effect of a small-molecule inhibitor that is able to block MA/CA cleavage even partially would be amplified by this transdominant negative effect on the highly orchestrated process of virion assembly.
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6
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Nucleocapsid protein function in early infection processes. Virus Res 2008; 134:39-63. [PMID: 18279991 DOI: 10.1016/j.virusres.2007.12.006] [Citation(s) in RCA: 124] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2007] [Revised: 12/13/2007] [Accepted: 12/13/2007] [Indexed: 01/15/2023]
Abstract
The role of nucleocapsid protein (NC) in the early steps of retroviral replication appears largely that of a facilitator for reverse transcription and integration. Using a wide variety of cell-free assay systems, the properties of mature NC proteins (e.g. HIV-1 p7(NC) or MLV p10(NC)) as nucleic acid chaperones have been extensively investigated. The effect of NC on tRNA annealing, reverse transcription initiation, minus-strand-transfer, processivity of reverse transcription, plus-strand-transfer, strand-displacement synthesis, 3' processing of viral DNA by integrase, and integrase-mediated strand-transfer has been determined by a large number of laboratories. Interestingly, these reactions can all be accomplished to varying degrees in the absence of NC; some are facilitated by both viral and non-viral proteins and peptides that may or may not be involved in vivo. What is one to conclude from the observation that NC is not strictly required for these necessary reactions to occur? NC likely enhances the efficiency of each of these steps, thereby vastly improving the productivity of infection. In other words, one of the major roles of NC is to enhance the effectiveness of early infection, thereby increasing the probability of productive replication and ultimately of retrovirus survival.
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7
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Schaubert KL, Price DA, Frahm N, Li J, Ng HL, Joseph A, Paul E, Majumder B, Ayyavoo V, Gostick E, Adams S, Marincola FM, Sewell AK, Altfeld M, Brenchley JM, Douek DC, Yang OO, Brander C, Goldstein H, Kan-Mitchell J. Availability of a diversely avid CD8+ T cell repertoire specific for the subdominant HLA-A2-restricted HIV-1 Gag p2419-27 epitope. THE JOURNAL OF IMMUNOLOGY 2007; 178:7756-66. [PMID: 17548613 PMCID: PMC2365726 DOI: 10.4049/jimmunol.178.12.7756] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
HLA-A2-restricted CTL responses to immunodominant HIV-1 epitopes do not appear to be very effective in the control of viral replication in vivo. In this study, we studied human CD8+ T cell responses to the subdominant HLA-A2-restricted epitope TV9 (Gag p24(19-27), TLNAWVKVV) to explore the possibility of increasing its immune recognition. We confirmed in a cohort of 313 patients, infected by clade B or clade C viruses, that TV9 is rarely recognized. Of interest, the functional sensitivity of the TV9 response can be relatively high. The potential T cell repertoires for TV9 and the characteristics of constituent clonotypes were assessed by ex vivo priming of circulating CD8+ T cells from healthy seronegative donors. TV9-specific CTLs capable of suppressing viral replication in vitro were readily generated, suggesting that the cognate T cell repertoire is not limiting. However, these cultures contained multiple discrete populations with a range of binding avidities for the TV9 tetramer and correspondingly distinct functional dependencies on the CD8 coreceptor. The lack of dominant clonotypes was not affected by the stage of maturation of the priming dendritic cells. Cultures primed by dendritic cells transduced to present endogenous TV9 were also incapable of clonal maturation. Thus, a diffuse TCR repertoire appeared to be an intrinsic characteristic of TV9-specific responses. These data indicate that subdominance is not a function of poor immunogenicity, cognate TCR repertoire availability, or the potential avidity properties thereof, but rather suggest that useful responses to this epitope are suppressed by competing CD8+ T cell populations during HIV-1 infection.
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Affiliation(s)
- Keri L. Schaubert
- Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI 48201
- Department of Biological Sciences, University of Texas, El Paso, TX 79968
| | - David A. Price
- Human Immunology Section, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
- Weatherall Institute of Molecular Medicine, University of Oxford, Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, United Kingdom
| | - Nicole Frahm
- Partners AIDS Research Center, Massachusetts General Hospital, Harvard Medical School, Charles-town, MA 02192
| | - Jinzhu Li
- Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI 48201
| | - Hwee L. Ng
- Department of Medicine and AIDS Institute, Center for Health Sciences, University of California, Los Angeles, CA 90095
| | - Aviva Joseph
- Department of Micro-biology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461
- Department of Pediatrics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Elyse Paul
- Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI 48201
| | - Biswanath Majumder
- Department of Infectious Diseases and Micro-biology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261
| | - Velpandi Ayyavoo
- Department of Infectious Diseases and Micro-biology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261
| | - Emma Gostick
- Weatherall Institute of Molecular Medicine, University of Oxford, Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, United Kingdom
| | - Sharon Adams
- Section of Immunogenetics, Department of Transfusion Medicine, National Institutes of Health, Bethesda, MD 20892
| | - Francesco M. Marincola
- Section of Immunogenetics, Department of Transfusion Medicine, National Institutes of Health, Bethesda, MD 20892
| | - Andrew K. Sewell
- Department of Medical Biochemistry and Immunology, Cardiff University, Cardiff, Wales, United Kingdom
| | - Marcus Altfeld
- Partners AIDS Research Center, Massachusetts General Hospital, Harvard Medical School, Charles-town, MA 02192
| | - Jason M. Brenchley
- Human Immunology Section, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Daniel C. Douek
- Human Immunology Section, Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Otto O. Yang
- Department of Medicine and AIDS Institute, Center for Health Sciences, University of California, Los Angeles, CA 90095
| | - Christian Brander
- Partners AIDS Research Center, Massachusetts General Hospital, Harvard Medical School, Charles-town, MA 02192
| | - Harris Goldstein
- Department of Micro-biology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461
- Department of Pediatrics, Albert Einstein College of Medicine, Bronx, New York 10461
| | - June Kan-Mitchell
- Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI 48201
- Department of Biological Sciences, University of Texas, El Paso, TX 79968
- Address correspondence and reprint requests to Dr. June Kan-Mitchell, Biological Sciences Building, University of Texas, 500 West University Avenue, El Paso, TX 79968. E-mail address:
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8
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Tang S, Ablan S, Dueck M, Ayala-López W, Soto B, Caplan M, Nagashima K, Hewlett IK, Freed EO, Levin JG. A second-site suppressor significantly improves the defective phenotype imposed by mutation of an aromatic residue in the N-terminal domain of the HIV-1 capsid protein. Virology 2006; 359:105-15. [PMID: 17055023 PMCID: PMC1851891 DOI: 10.1016/j.virol.2006.09.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Revised: 07/26/2006] [Accepted: 09/13/2006] [Indexed: 12/30/2022]
Abstract
The HIV-1 capsid (CA) protein plays an important role in virus assembly and infectivity. Previously, we showed that Ala substitutions in the N-terminal residues Trp23 and Phe40 cause a severely defective phenotype. In searching for mutations at these positions that result in a non-lethal phenotype, we identified one candidate, W23F. Mutant virions contained aberrant cores, but unlike W23A, also displayed some infectivity in a single-round replication assay and delayed replication kinetics in MT-4 cells. Following long-term passage in MT-4 cells, two second-site mutations were isolated. In particular, the W23F/V26I mutation partially restored the wild-type phenotype, including production of particles with conical cores and wild-type replication kinetics in MT-4 cells. A structural model is proposed to explain the suppressor phenotype. These findings describe a novel occurrence, namely suppression of a mutation in a hydrophobic residue that is critical for maintaining the structural integrity of CA and proper core assembly.
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Affiliation(s)
- Shixing Tang
- Viral Gene Regulation Section, Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Building 6B, Room 216, Bethesda, Maryland 20892-2780, USA
- Laboratory of Molecular Virology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA
| | - Sherimay Ablan
- Virus-Cell Interaction Section, HIV Drug Resistance Program, SAIC Frederick, Inc., National Cancer Institute at Frederick, Frederick, Maryland 21702, USA
| | - Megan Dueck
- Viral Gene Regulation Section, Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Building 6B, Room 216, Bethesda, Maryland 20892-2780, USA
| | - Wilfredo Ayala-López
- Viral Gene Regulation Section, Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Building 6B, Room 216, Bethesda, Maryland 20892-2780, USA
| | - Brenda Soto
- Viral Gene Regulation Section, Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Building 6B, Room 216, Bethesda, Maryland 20892-2780, USA
| | - Margaret Caplan
- Viral Gene Regulation Section, Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Building 6B, Room 216, Bethesda, Maryland 20892-2780, USA
| | - Kunio Nagashima
- Image Analysis Laboratory, SAIC Frederick, Inc., National Cancer Institute at Frederick, Frederick, Maryland 21702, USA
| | - Indira K. Hewlett
- Laboratory of Molecular Virology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA
| | - Eric O. Freed
- Virus-Cell Interaction Section, HIV Drug Resistance Program, SAIC Frederick, Inc., National Cancer Institute at Frederick, Frederick, Maryland 21702, USA
| | - Judith G. Levin
- Viral Gene Regulation Section, Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, National Institutes of Health, Building 6B, Room 216, Bethesda, Maryland 20892-2780, USA
- *Corresponding author. Fax: +1 301 496 0243, Email address: (J. G. Levin)
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9
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Kamada K, Yoshida A, Khamsri B, Piroozmand A, Yamashita T, Uchiyama T, Fujita M, Adachi A. Construction of gag-chimeric viruses between HIV-1 and SIVmac that are capable of productive multi-cycle infection. Microbes Infect 2006; 8:1075-81. [PMID: 16520079 DOI: 10.1016/j.micinf.2005.11.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Accepted: 11/04/2005] [Indexed: 11/24/2022]
Abstract
Forty-nine recombinant viral clones between human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus from the rhesus monkey (SIVmac), which carry chimeric gag (capsid/p2 region) genes in the background of the HIV-1 genome, were constructed to establish an HIV-1/monkey infection model system for human AIDS. Upon transfection, all the recombinants generated progeny virions at a level comparable to the parental HIV-1 clone and no major abnormalities were found in the virions, as examined by Western blot analysis. In infection experiments, 18 recombinants grew in human lymphocytic cells and six of these clones propagated as well as the parental virus, as monitored by virion associated-reverse transcriptase production. By contrast, none of the recombinants grew at a detectable level in monkey lymphocytic cells. The defective replication site(s) in human cells for non-infectious recombinants was mapped to the step before and/or during reverse transcription. Our results described here showed that HIV-1 type chimeric viruses between HIV-1 and SIVmac, which are capable of spreading productive infection, are readily constructed throughout the capsid/p2 region. In addition, it is suggested that there may be a viral determinant(s), other than Gag, responsible for the species-specific tropism of HIV-1 and which is associated with viral DNA synthesis.
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Affiliation(s)
- Kazuya Kamada
- Department of Virology, Institute of Health Biosciences, The University of Tokushima Graduate School, 3-18-15 Kuramoto-cho, Tokushima-shi, Tokushima 770-8503, Japan
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10
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Rulli SJ, Muriaux D, Nagashima K, Mirro J, Oshima M, Baumann JG, Rein A. Mutant murine leukemia virus Gag proteins lacking proline at the N-terminus of the capsid domain block infectivity in virions containing wild-type Gag. Virology 2006; 347:364-71. [PMID: 16427108 DOI: 10.1016/j.virol.2005.12.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2005] [Revised: 09/12/2005] [Accepted: 12/12/2005] [Indexed: 10/25/2022]
Abstract
We have investigated the properties of murine leukemia virus Gag mutants in which the p12-CA cleavage site is altered. In one mutant, the cleavage is blocked; in the other, the conserved proline at the N-terminus of CA has been replaced with glycine. No infectivity was detected in either mutant. Mutant particles cannot synthesize full-length DNA upon infecting permissive cells. Particles composed of a mixture of wild-type and mutant proteins have severely impaired infectivity. These mixed particles are defective in their ability to synthesize DNA upon infection, but this defect is less severe than the loss of infectivity. Thus, proteins lacking the correct N-terminus of CA inhibit DNA synthesis and also interfere with formation or integration of a full-length, normal provirus. The results imply that CA proteins function as part of a large, highly organized structure in reverse transcription and apparently at a later step as well.
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MESH Headings
- Animals
- Capsid Proteins/genetics
- Capsid Proteins/physiology
- Capsid Proteins/therapeutic use
- Cell Line
- DNA, Circular/biosynthesis
- DNA, Viral/biosynthesis
- Gene Products, gag/genetics
- Gene Products, gag/physiology
- Gene Products, gag/therapeutic use
- Leukemia Virus, Murine/genetics
- Leukemia Virus, Murine/physiology
- Leukemia Virus, Murine/ultrastructure
- Leukemia, Experimental/prevention & control
- Microscopy, Electron
- Mutation
- Proline/deficiency
- RNA, Viral/metabolism
- Retroviridae Infections/prevention & control
- Tumor Virus Infections/prevention & control
- Viral Proteins/genetics
- Viral Proteins/physiology
- Virion/physiology
- Virion/ultrastructure
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Affiliation(s)
- S J Rulli
- HIV Drug Resistance Program, SAIC Frederick, National Cancer Institute-Frederick, P.O. Box B, Frederick, MD 21702-1201, USA
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11
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Abstract
Viral fitness is defined by the ability of an individual genotype to produce infectious progeny in a specific environment. For HIV the environment is never constant but rather fluctuates in time and space. For instance, environmental factors that determine viral fitness during transmission from host to host are different to the pressures from either cytotoxic T-lymphocytes (CTLs) or antiviral drugs. Consequently, viral fitness is highly dependent on the environment and the accurate determination of this value therefore depends strongly on the chosen environmental setting. This review describes how the host environment imposes selective pressures on the virus that shape its genotype and fitness. The most important environments that the virus encounters throughout its life cycle and during natural infection are discussed. In order of appearance, CTLs are discussed, followed by neutralising antibodies and antiretroviral drug treatment. It then goes on to describe receptor molecules that mediate viral entry and intracellular restriction factors, which represent selective pressures that are present directly from the start of a natural infection. It concludes by discussing the complexity of viral fitness and how an accurate measure of viral fitness eventually may, for example, contribute to the improvement of antiretroviral therapy or help in the formulation of an optimal vaccination strategy.
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Affiliation(s)
- Tim van Opijnen
- Department of Human Retrovirology, Academic Medical Centre, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
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12
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Abdurahman S, Höglund S, Goobar-Larsson L, Vahlne A. Selected amino acid substitutions in the C-terminal region of human immunodeficiency virus type 1 capsid protein affect virus assembly and release. J Gen Virol 2004; 85:2903-2913. [PMID: 15448352 DOI: 10.1099/vir.0.80137-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The capsid protein (CA or p24) of human immunodeficiency virus type 1 (HIV-1) plays a major role both early and late in the virus replication cycle. Many studies have suggested that the C-terminal domain of this protein is involved in dimerization and proper assembly of the viral core. Point mutations were introduced in two conserved sites of this region and their effects on viral protein expression, particle assembly and infectivity were studied. Eight different mutants (L205A+P207A, L205A, P207A, 223GPG225AAA, G223A, P224A, G225A and V221G) of the infectious clone pNL4-3 were constructed. Most substitutions had no substantial effect on HIV-1 protein synthesis, yet they impaired viral infectivity and particle production. The two mutants P207A and V221G also had a profound effect on Gag–Pol protein processing in HeLa–tat cells. However, these results were cell line-specific and Gag–Pol processing of P207A was not affected in 293T cells. In HeLa–tat cells, no virus particles were detected with the P207A mutation, whereas the other mutant virus particles were heterogeneous in size and morphology. None of the mutants showed normal, mature, conical core structures in HeLa–tat cells. These results indicate that the two conserved sequences in the C-terminal CA domain are essential for proper morphogenesis and infectivity of HIV-1 particles.
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Affiliation(s)
- Samir Abdurahman
- Division of Clinical Virology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Stefan Höglund
- Department of Biochemistry, Biomedical Center, Uppsala University, Uppsala, Sweden
| | - Laura Goobar-Larsson
- Division of Clinical Chemistry, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Anders Vahlne
- Division of Clinical Virology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
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13
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Leslie AJ, Pfafferott KJ, Chetty P, Draenert R, Addo MM, Feeney M, Tang Y, Holmes EC, Allen T, Prado JG, Altfeld M, Brander C, Dixon C, Ramduth D, Jeena P, Thomas SA, St John A, Roach TA, Kupfer B, Luzzi G, Edwards A, Taylor G, Lyall H, Tudor-Williams G, Novelli V, Martinez-Picado J, Kiepiela P, Walker BD, Goulder PJR. HIV evolution: CTL escape mutation and reversion after transmission. Nat Med 2004; 10:282-9. [PMID: 14770175 DOI: 10.1038/nm992] [Citation(s) in RCA: 676] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2003] [Accepted: 01/08/2004] [Indexed: 01/17/2023]
Abstract
Within-patient HIV evolution reflects the strong selection pressure driving viral escape from cytotoxic T-lymphocyte (CTL) recognition. Whether this intrapatient accumulation of escape mutations translates into HIV evolution at the population level has not been evaluated. We studied over 300 patients drawn from the B- and C-clade epidemics, focusing on human leukocyte antigen (HLA) alleles HLA-B57 and HLA-B5801, which are associated with long-term HIV control and are therefore likely to exert strong selection pressure on the virus. The CTL response dominating acute infection in HLA-B57/5801-positive subjects drove positive selection of an escape mutation that reverted to wild-type after transmission to HLA-B57/5801-negative individuals. A second escape mutation within the epitope, by contrast, was maintained after transmission. These data show that the process of accumulation of escape mutations within HIV is not inevitable. Complex epitope- and residue-specific selection forces, including CTL-mediated positive selection pressure and virus-mediated purifying selection, operate in tandem to shape HIV evolution at the population level.
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Affiliation(s)
- A J Leslie
- Department of Pediatrics, Fuffield Department of Medicine, Peter Medawar Building for Pathogen Research, University of Oxford, Oxford OX1 3SY, UK
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14
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Fujita M, Yoshida A, Miyaura M, Sakurai A, Akari H, Koyama AH, Adachi A. Cyclophilin A-independent replication of a human immunodeficiency virus type 1 isolate carrying a small portion of the simian immunodeficiency virus SIV(MAC) gag capsid region. J Virol 2001; 75:10527-31. [PMID: 11581426 PMCID: PMC114632 DOI: 10.1128/jvi.75.21.10527-10531.2001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hybrid viruses between human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus strain mac (SIV(MAC)) are invaluable to various fields of HIV-1 research. To date, however, no replication-competent HIV-1 strain containing the gag capsid (CA) region of SIV(MAC) has been reported. To obtain the viable gag gene chimeric virus in an HIV-1 background, seven HIV-1 strains carrying a part of SIV(MAC) CA or a small deletion in the CA region were constructed and examined for their biological and biochemical characteristics. While all the recombinants and mutants were found to express Gag and to produce progeny virions on transfection, only one chimeric virus, which has 18 bp of SIV gag CA sequence in place of the region encoding the HIV-1 CA cyclophilin A (CyPA)-binding loop, was infectious for human cell lines. Although this chimeric virus was unable to grow in monkey lymphocytic cells like wild-type (wt) HIV-1 did, it grew much better than wt virus in the presence of cyclosporin A in a human cell line which supports HIV-1 replication in a CyPA-dependent manner. These results indicate that the transfer of a small portion of the SIV(MAC) CA region to HIV-1 could confer the CyPA-independent replication potential of SIV(MAC) on the virus.
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Affiliation(s)
- M Fujita
- Department of Virology, The University of Tokushima School of Medicine, Tokushima-shi, Tokushima 770-8503, Japan
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15
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Koh K, Miyaura M, Yoshida A, Sakurai A, Fujita M, Adachi A. Cell-dependent gag mutants of HIV-1 are crucially defective at the stage of uncoating/reverse transcription in non-permissive cells. Microbes Infect 2000; 2:1419-23. [PMID: 11099927 DOI: 10.1016/s1286-4579(00)01295-8] [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: 10/18/2022]
Abstract
We have previously shown that some of the human immunodeficiency virus type 1 (HIV-1) gag matrix (MA), capsid (CA), and nucleocapsid (NC) mutants display host-cell-dependent replication potential, and that they are defective at the early phase of the virus replication cycle in non-permissive cells. To determine the defective replication stage of the cell-dependent mutants precisely, the processes of virus entry into cells and virus DNA synthesis were monitored by the highly sensitive enzyme-linked immunosorbent assay and polymerase chain reaction amplification analysis. The results obtained indicated that all the cell-dependent MA, CA and NC mutants are defective at the stage of uncoating/reverse transcription, and that a cellular factor(s) is involved in this process.
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Affiliation(s)
- K Koh
- Department of Virology, School of Medicine, The University of Tokushima, 770-8503, Tokushima, Japan
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16
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Shimano R, Inubushi R, Oshima Y, Adachi A. Inhibition of HIV/SIV replication by dominant negative Gag mutants. Virus Genes 1999; 18:197-201. [PMID: 10456787 DOI: 10.1023/a:1008054111697] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
There are several major strategies against HIV/AIDS. Of these, the gene therapy is a novel, challenging, and promising one. The target genes, which have been extensively studied for the potential gene therapy of HIV/AIDS, include those of cellular and viral origins. Especially, trans-dominant negative Tat, Rev, Env, Pol, and Gag mutants of HIV have currently attracted considerable attention. In this brief review, we summarize the nature of the HIV/SIV mutants of this category and discuss their future use for gene therapy with special reference to the dominant negative Gag mutants of HIV-1.
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Affiliation(s)
- R Shimano
- Department of Virology, The University of Tokushima School of Medicine, Japan
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17
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Adachi A, Tamaki M, Shimano R, Inubushi R, Naito T, Yoshida K, Oshima Y, Kawamura M, Koyama AH. Cell-dependent replication potentials of HIV-1 gag mutants. Microbes Infect 1999; 1:671-6. [PMID: 10611744 DOI: 10.1016/s1286-4579(99)80068-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An infectious molecular clone of human immunodeficiency virus type 1 (HIV-1), designated pNLaiKH, which is tropic for both lymphocytic and monocytic cells, was constructed. To study the early function of HIV-1 Gag proteins in two types of cells, the mutations known to give host cell-dependent early defects were introduced into pNLaiKH, and the replication potentials and defective replication sites in the cells of the resultant mutants were monitored. All mutants grew in some lymphocytic cells, but not at all in monocytic cells. A nucleocapsid mutant was found to be defective at an early replication phase in all the cell lines to various extent, as expected. In contrast, a matrix mutant and a capsid mutant displayed a replication defect in a producer-cell-dependent manner. These results demonstrated that complex interactions of cell factors and Gag proteins are involved in an early process of HIV-1 replication.
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Affiliation(s)
- A Adachi
- Department of Virology, The University of Tokushima School of Medicine, Tokushima 770-8503, Japan
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18
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Cimarelli A, Luban J. Translation elongation factor 1-alpha interacts specifically with the human immunodeficiency virus type 1 Gag polyprotein. J Virol 1999; 73:5388-401. [PMID: 10364286 PMCID: PMC112595 DOI: 10.1128/jvi.73.7.5388-5401.1999] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) gag-encoded proteins play key functions at almost all stages of the viral life cycle. Since these functions may require association with cellular factors, the HIV-1 matrix protein (MA) was used as bait in a yeast two-hybrid screen to identify MA-interacting proteins. MA was found to interact with elongation factor 1-alpha (EF1alpha), an essential component of the translation machinery that delivers aminoacyl-tRNA to ribosomes. EF1alpha was then shown to bind the entire HIV-1 Gag polyprotein. This interaction is mediated not only by MA, but also by the nucleocapsid domain, which provides a second, independent EF1alpha-binding site on the Gag polyprotein. EF1alpha is incorporated within HIV-1 virion membranes, where it is cleaved by the viral protease and protected from digestion by exogenously added subtilisin. The specificity of the interaction is demonstrated by the fact that EF1alpha does not bind to nonlentiviral MAs and does not associate with Moloney murine leukemia virus virions. The Gag-EF1alpha interaction appears to be mediated by RNA, in that basic residues in MA and NC are required for binding to EF1alpha, RNase disrupts the interaction, and a Gag mutant with undetectable EF1alpha-binding activity is impaired in its ability to associate with tRNA in cells. Finally, the interaction between MA and EF1alpha impairs translation in vitro, a result consistent with a previously proposed model in which inhibition of translation by the accumulation of Gag serves to release viral RNA from polysomes, permitting the RNA to be packaged into nascent virions.
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Affiliation(s)
- A Cimarelli
- Departments of Microbiology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
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19
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Shimano R, Inubushi R, Amano K, Ogasawara T, Akari H, Koyama AH, Kawamura M, Adachi A. Complete inhibition of SIVmac replication by its capsid mutants. Virus Genes 1998; 17:43-8. [PMID: 9778787 DOI: 10.1023/a:1008001000878] [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: 11/12/2022]
Abstract
Mutations were introduced into a genomic region encoding the C-terminal portion of Gag capsid protein of pathogenic simian immunodeficiency virus (SIVmac239). All the mutants generated were defective for virion production and were non-infectious for monkey cells. They all efficiently suppressed the replication of wild type SIVmac in monkey cells. These results were in good agreement with those obtained for human immunodeficiency virus type 1, showing the importance of SIV/monkey model system for studies on Gag.
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Affiliation(s)
- R Shimano
- Department of Virology, School of Medicine, University of Tokushima, Japan
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20
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Kawamura M, Shimano R, Inubushi R, Akari H, Adachi A. Early function of HIV-1 Gag proteins is cell-dependent. Biochem Biophys Res Commun 1998; 248:899-903. [PMID: 9704024 DOI: 10.1006/bbrc.1998.9065] [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: 11/22/2022]
Abstract
Various gag gene mutants of human immunodeficiency virus type 1 (HIV-1) were monitored for their replication potentials and defective replication sites in various CD4-positive T-cell lines. Some matrix, capsid, and nucleocapsid mutants displayed a replication defect in a cell-dependent manner. The single-round replication assays demonstrated that these mutants were defective at an early infection phase also in a cell-dependent way. These results indicated that interaction of a cell factor(s) and Gag proteins is involved in an early process of HIV-1 replication.
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Affiliation(s)
- M Kawamura
- Department of Virology, University of Tokushima School of Medicine, Japan
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21
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Shimano R, Inubushi R, Fukumori T, Tamaki M, Oshima Y, Kawamura M, Adachi A. Suppression of HIV-2 replication by HIV-1 gag mutants. Biochem Biophys Res Commun 1998; 248:418-21. [PMID: 9675152 DOI: 10.1006/bbrc.1998.8975] [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: 11/22/2022]
Abstract
Gag gene mutants of human immunodeficiency virus type 1 (HIV-1) were analyzed for their potentials of inhibiting the replication of wild-type (wt) HIV-2, the second AIDS virus, in a single-round of viral replication. Of twenty-two HIV-1 gag mutants examined, seven were found to efficiently interfere with the replication of wt HIV-2. Some mutants, which can suppress the replication of wt HIV-1, did not show this inhibitory effect. These mutants were defective at the late phase of viral replication. A mutant designated NL-C1a was demonstrated to be very effective against the replication of HIV-1 and HIV-2 in monocytic cells as well as in lymphocytic cells.
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Affiliation(s)
- R Shimano
- Department of Virology, The University of Tokushima School of Medicine, Tokushima, 770-8503, Japan
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22
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Inubushi R, Shimano R, Oshima Y, Adachi A. The potential of various HIV-1 mutants to inhibit the replication of wild-type virus. Biochem Biophys Res Commun 1998; 247:349-52. [PMID: 9642129 DOI: 10.1006/bbrc.1998.8790] [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: 11/22/2022]
Abstract
We have previously demonstrated that many of gag mutants of human immunodeficiency virus type 1 (HIV-1) inhibited the replication of wild-type (wt) HIV-1. In this study, various HIV-1 mutants were systematically analyzed with respect to their ability to suppress the replication of wt HIV-1. Sixteen mutants of all eight HIV-1 genes other than gag were evaluated for their inhibitory effects. Only an env mutant designated NL-Hi efficiently interfered with the replication of wt HIV-1 in a single round of infection. The NL-Hi did not affect the late replication processes of wt virus, including transcription, translation, and assembly/release. Virions produced in the presence of the mutant Env were defective for the viral entry process in the early phase of HIV-1 replication cycle.
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Affiliation(s)
- R Inubushi
- Department of Virology, The University of Tokushima School of Medicine, Tokushima, 770-8503, Japan
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23
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Shimano R, Iida S, Fukumori T, Yamamoto Y, Kawamura M, Furuta RA, Adachi A. Inhibition of HIV replication by capsid mutant C6b. Biochem Biophys Res Commun 1998; 242:313-6. [PMID: 9446791 DOI: 10.1006/bbrc.1997.7963] [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: 02/05/2023]
Abstract
A Gag capsid mutant of human immunodeficiency virus type 1 (HIV-1) designated C6b was biologically and biochemically characterized with respect to its ability to suppress the replication of wild-type (wt) HIV. The C6b efficiently interfered with the replication of wt HIV-1 in the cleavage of Gag precursor, and also in the early replication process before or during viral DNA synthesis after viral penetration. The C6b Gag appeared to be unable to form chimeric multimers with HIV-2 Gag and failed to inhibit the replication of wt HIV-2.
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Affiliation(s)
- R Shimano
- Department of Virology, School of Medicine, University of Tokushima, Japan
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