scholarly journals Capsid Proteins from Human Immunodeficiency Virus Type 1 and Simian Immunodeficiency Virus SIVmac Can Coassemble into Mature Cores of Infectious Viruses

2008 ◽  
Vol 82 (17) ◽  
pp. 8253-8261 ◽  
Author(s):  
Jianbo Chen ◽  
Vinay K. Pathak ◽  
Weiqun Peng ◽  
Wei-Shau Hu
Keyword(s):  
Human Immunodeficiency Virus ◽  
Simian Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Infectious Virus ◽  
Virus Infectivity ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Ca Protein

ABSTRACT We have recently shown that the Gag polyproteins from human immunodeficiency virus type 1 (HIV-1) and HIV-2 can coassemble and functionally complement each other. During virion maturation, the Gag polyproteins undergo proteolytic cleavage to release mature proteins including capsid (CA), which refolds and forms the outer shell of a cone-shaped mature core. Less than one-half of the CA proteins present within the HIV-1 virion are required to form the mature core. Therefore, it is unclear whether the mature core in virions containing both HIV-1 and HIV-2 Gag consists of CA proteins from a single virus or from both viruses. To determine whether CA proteins from two different viruses can coassemble into mature cores of infectious viruses, we exploited the specificity of the tripartite motif 5α protein from the rhesus monkey (rhTRIM5α) for cores containing HIV-1 CA (hCA) but not the simian immunodeficiency virus SIVmac CA protein (sCA). If hCA and sCA cannot coassemble into the same core when equal amounts of sCA and hCA are coexpressed, the infectivities of such virus preparations in cells should be inhibited less than twofold by rhTRIM5α. However, if hCA and sCA can coassemble into the same core structure to form a mixed core, rhTRIM5α would be able to recognize such cores and significantly restrict virus infectivity. We examined the restriction phenotypes of viruses containing both hCA and sCA. Our results indicate that hCA and sCA can coassemble into the same mature core to produce infectious virus. To our knowledge, this is the first demonstration of functional coassembly of heterologous CA protein into the retroviral core.

scholarly journals Interaction between the Cytoplasmic Domain of ICAM-1 and Pr55Gag Leads to Acquisition of Host ICAM-1 by Human Immunodeficiency Virus Type 1

2004 ◽  
Vol 78 (21) ◽  
pp. 11916-11925 ◽  
Author(s):  
Yannick Beauséjour ◽  
Michel J. Tremblay
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Adhesion Molecule ◽  
Cytoplasmic Domain ◽  
Virus Infectivity ◽  
Immunodeficiency Virus ◽  
Selective Incorporation ◽  
Hiv 1

ABSTRACT We have examined the molecular basis for the selective incorporation of the adhesion molecule ICAM-1 within human immunodeficiency virus type 1 (HIV-1). The process of ICAM-1 incorporation was investigated by using different ICAM-1 constructs in combination with virus capture and immunoprecipitation studies, Western blot and confocal microscopy analyses, and infectivity assays. Experiments conducted with viruses bearing a truncated version of ICAM-1 revealed that the cytoplasmic domain of ICAM-1 governs insertion of this adhesion molecule into HIV-1. Further experiments suggested that there is an association between ICAM-1 and the virus-encoded Pr55Gag polyprotein. This study represents the first demonstration that structural Gag polyproteins play a key role in the uptake of a host-derived cell surface by the virus entity. Taken together, our results indicate that interactions between viral and cellular proteins are responsible for the selective uptake of host ICAM-1 by HIV-1. This observation describes a new strategy by which HIV-1 can modulate its replicative cycle, considering that insertion of ICAM-1 within nascent virions has been shown to increase virus infectivity.

scholarly journals Cholesterol Depletion of Human Immunodeficiency Virus Type 1 and Simian Immunodeficiency Virus with β-Cyclodextrin Inactivates and Permeabilizes the Virions: Evidence for Virion-Associated Lipid Rafts

2003 ◽  
Vol 77 (15) ◽  
pp. 8237-8248 ◽  
Author(s):  
David R. M. Graham ◽  
Elena Chertova ◽  
Joanne M. Hilburn ◽  
Larry O. Arthur ◽  
James E. K. Hildreth
Keyword(s):  
Human Immunodeficiency Virus ◽  
Lipid Rafts ◽  
Simian Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Viral Rna ◽  
Host Proteins ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Recent evidence suggests that human immunodeficiency virus type 1 (HIV-1) particles assemble and bud selectively through areas in the plasma membrane of cells that are highly enriched with glycosylphosphatidylinositol-anchored proteins and cholesterol, called lipid rafts. Since cholesterol is required to maintain lipid raft structure and function, we proposed that virion-associated cholesterol removal with the compound 2-hydroxy-propyl-β-cyclodextrin (β-CD) might be disruptive to HIV-1 and simian immunodeficiency virus (SIV). We examined the effect of β-CD on the structure and infectivity of cell-free virions. We found that β-CD inactivated HIV-1 and SIV in a dose-dependent manner and permeabilized the viral membranes, resulting in the loss of mature Gag proteins (capsid, matrix, nucleocapsid, p1, and p6) without loss of the envelope glycoproteins. SIV also lost reverse transcriptase (RT), integrase (IN), and viral RNA. IN appeared to be only slightly diminished in HIV-1, and viral RNA, RT, matrix, and nucleocapsid proteins were retained in HIV-1 but to a much lesser degree. Host proteins located internally in the virus (actin, moesin, and ezrin) and membrane-associated host proteins (major histocompatibility complex classes I and II) remained associated with the treated virions. Electron microscopy revealed that under conditions that permeabilized the viruses, holes were present in the viral membranes and the viral core structure was perturbed. These data provide evidence that an intact viral membrane is required to maintain mature virion core integrity. Since the viruses were not fixed before β-CD treatment and intact virion particles were recovered, the data suggest that virions may possess a protein scaffold that can maintain overall structure despite disruptions in membrane integrity.

scholarly journals LFA-1 Is a Key Determinant for Preferential Infection of Memory CD4+ T Cells by Human Immunodeficiency Virus Type 1

2005 ◽  
Vol 79 (21) ◽  
pp. 13714-13724 ◽  
Author(s):  
Mélanie R. Tardif ◽  
Michel J. Tremblay
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Cell Subset ◽  
T Cell Subsets ◽  
Virus Infectivity ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Memory CD4+ T cells are considered a stable latent reservoir for human immunodeficiency virus type 1 (HIV-1) and a barrier to eradication of this retroviral infection in patients under therapy. It has been shown that memory CD4+ T cells are preferentially infected with HIV-1, but the exact mechanism(s) responsible for this higher susceptibility remains obscure. Previous findings indicate that incorporation of host-derived intercellular adhesion molecule 1 (ICAM-1) in HIV-1 increases virus infectivity. To measure the putative involvement of virus-anchored ICAM-1 in the preferential infection of memory cells by HIV-1, quiescent and activated naive and memory T-cell subsets were exposed to isogenic virions either lacking or bearing ICAM-1. Memory CD4+ T cells were found to be more susceptible than naive CD4+ T cells to infection with ICAM-1-bearing virions, as exemplified by a more important virus replication, an increase in integrated viral DNA copies, and a more efficient entry process. Interactions between virus-associated host ICAM-1 and cell surface LFA-1 under a cluster formation seem to be responsible for the preferential HIV-1 infection of the memory cell subset. Altogether, these data shed light on a potential mechanism by which HIV-1 preferentially targets long-lived memory CD4+ T cells.

scholarly journals Polyubiquitination of APOBEC3G Is Essential for Its Degradation by HIV-1 Vif

2010 ◽  
Vol 84 (9) ◽  
pp. 4840-4844 ◽  
Author(s):  
Qiujia Shao ◽  
Yudi Wang ◽  
James E. K. Hildreth ◽  
Bindong Liu
Keyword(s):  
Human Immunodeficiency Virus ◽  
Simian Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Proteasomal Degradation ◽  
Human Cells ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Proteasomal degradation of APOBEC3G is a critical step for human immunodeficiency virus type 1 (HIV-1) replication. However, the necessity for polyubiquitination of APOBEC3G in this process is still controversial. In this study, we showed that although macaque simian immunodeficiency virus (SIVmac) Vif is more stable than HIV-1 Vif in human cells, SIVmac Vif induces degradation of APBOEC3G as efficiently as HIV-1 Vif. Overexpression of APOBEC3G or lysine-free APOBEC3G stabilized HIV-1 Vif, indicating that APOBEC3G degradation is independent of the degradation of Vif. Furthermore, an in vivo polyubiquitination assay showed that lysine-free APOBEC3G was also polyubiquitinated. These data suggest that polyubiquitination of APOBEC3G, not that of HIV-1 Vif, is crucial for APOBEC3G degradation.

scholarly journals The DNA Deaminase Activity of Human APOBEC3G Is Required for Ty1, MusD, and Human Immunodeficiency Virus Type 1 Restriction

2008 ◽  
Vol 82 (6) ◽  
pp. 2652-2660 ◽  
Author(s):  
April J. Schumacher ◽  
Guylaine Haché ◽  
Donna A. MacDuff ◽  
William L. Brown ◽  
Reuben S. Harris
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Virus Infectivity ◽  
Repair System ◽  
Cytosine Deamination ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Human Apobec3g

ABSTRACT Human APOBEC3G and several other APOBEC3 proteins have been shown to inhibit the replication of a variety of retrotransposons and retroviruses. All of these enzymes can deaminate cytosines within single-strand DNA, but the overall importance of this conserved activity in retroelement restriction has been questioned by reports of deaminase-independent mechanisms. Here, three distinct retroelements, a yeast retrotransposon, Ty1, a murine endogenous retrovirus, MusD, and a lentivirus, human immunodeficiency virus type 1 (HIV-1), were used to evaluate the relative contributions of deaminase-dependent and -independent mechanisms. Although human APOBEC3G can restrict the replication of all three of these retroelements, APOBEC3G lacking the catalytic glutamate (E259Q) was clearly defective. This phenotype was particularly clear in experiments with low levels of APOBEC3G expression. In contrast, purposeful overexpression of APOBEC3G-E259Q was able to cause modest to severe reductions in the replication of Ty1, MusD, and HIV-1(ΔVif). The importance of these observations was highlighted by data showing that CEM-SS T-cell lines expressing near-physiologic levels of APOBEC3G-E259Q failed to inhibit the replication of HIV-1(ΔVif), whereas similar levels of wild-type APOBEC3G fully suppressed virus infectivity. Despite the requirement for DNA deamination, uracil DNA glycosylase did not modulate APOBEC3G-dependent restriction of Ty1 or HIV-1(ΔVif), further supporting prior studies indicating that the major uracil excision repair system of cells is not involved. In conclusion, the absolute requirement for the catalytic glutamate of APOBEC3G in Ty1, MusD, and HIV-1 restriction strongly indicates that DNA cytosine deamination is an essential part of the mechanism.

scholarly journals Heterologous Human Immunodeficiency Virus Type 1 Lentiviral Vectors Packaging a Simian Immunodeficiency Virus-Derived Genome Display a Specific Postentry Transduction Defect in Dendritic Cells

2003 ◽  
Vol 77 (17) ◽  
pp. 9295-9304 ◽  
Author(s):  
Caroline Goujon ◽  
Loraine Jarrosson-Wuilleme ◽  
Jeanine Bernaud ◽  
Dominique Rigal ◽  
Jean-Luc Darlix ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Human Immunodeficiency Virus ◽  
Dendritic Cells ◽  
Simian Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Cell Types ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Heterologous lentiviral vectors (LVs) represent a way to address safety concerns in the field of gene therapy by decreasing the possibility of genetic recombination between vector and packaging constructs and the generation of replication-competent viruses. Using described LVs based on human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus MAC251 (SIVMAC251), we asked whether heterologous virion particles in which trans-acting factors belonged to HIV-1 and cis elements belonged to SIVMAC251 (HIV-siv) would behave as parental homologous vectors in all cell types. To our surprise, we found that although the heterologous HIV-siv vector was as infectious as its homologous counterpart in most human cells, it was defective in the transduction of dendritic cells (DCs) and, to a lesser extent, macrophages. In DCs, the main postentry defect was observed in the formation of two-long-terminal-repeat circles, despite the fact that full-length proviral DNA was being synthesized and was associated with the nucleus. Taken together, our data suggest that heterologous HIV-siv vectors display a cell-dependent infectivity defect, most probably at a post-nuclear entry migration step. As homologous HIV and SIV vectors do transduce DCs, we believe that these results underscore the importance of a conserved interaction between cis elements and trans-acting viral factors that is lost or suboptimal in heterologous vectors and essential only in the transduction of certain cell types. For gene therapy purposes, these findings indicate that the cellular tropism of LVs can be modulated not only through the use of distinct envelope proteins or tissue-specific promoters but also through the specific combinatorial use of packaging and transfer vector constructs.

scholarly journals Vaccine-Induced Linear Epitope-Specific Antibodies to Simian Immunodeficiency Virus SIVmac239 Envelope Are Distinct from Those Induced to the Human Immunodeficiency Virus Type 1 Envelope in Nonhuman Primates

2015 ◽  
Vol 89 (16) ◽  
pp. 8643-8650 ◽  
Author(s):  
Xiaoying Shen ◽  
Ryan Duffy ◽  
Robert Howington ◽  
Alethea Cope ◽  
Shanmugalakshmi Sadagopal ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Simian Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Immunodeficiency Virus ◽  
Linear Epitopes ◽  
Binding Antibody ◽  
Antibody Specificities ◽  
Hiv 1

To evaluate antibody specificities induced by simian immunodeficiency virus (SIV) versus human immunodeficiency virus type 1 (HIV-1) envelope antigens in nonhuman primate (NHP), we profiled binding antibody responses to linear epitopes in NHP studies with HIV-1 or SIV immunogens. We found that, overall, HIV-1 Env IgG responses were dominated by V3, with the notable exception of the responses to the vaccine strain A244 Env that were dominated by V2, whereas the anti-SIVmac239 Env responses were dominated by V2 regardless of the vaccine regimen.

scholarly journals Efavirenz Therapy in Rhesus Macaques Infected with a Chimera of Simian Immunodeficiency Virus Containing Reverse Transcriptase from Human Immunodeficiency Virus Type 1

2004 ◽  
Vol 48 (9) ◽  
pp. 3483-3490 ◽  
Author(s):  
Michael J. Hofman ◽  
Joanne Higgins ◽  
Timothy B. Matthews ◽  
Niels C. Pedersen ◽  
Chalet Tan ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Reverse Transcriptase ◽  
Simian Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Rhesus Macaques ◽  
Immunodeficiency Virus ◽  
Resistant Mutants ◽  
Hiv 1

ABSTRACT The specificity of nonnucleoside reverse transcriptase (RT) inhibitors (NNRTIs) for the RT of human immunodeficiency virus type 1 (HIV-1) has prevented the use of simian immunodeficiency virus (SIV) in the study of NNRTIs and NNRTI-based highly active antiretroviral therapy. However, a SIV-HIV-1 chimera (RT-SHIV), in which the RT from SIVmac239 was replaced with the RT-encoding region from HIV-1, is susceptible to NNRTIs and is infectious to rhesus macaques. We have evaluated the antiviral activity of efavirenz against RT-SHIV and the emergence of efavirenz-resistant mutants in vitro and in vivo. RT-SHIV was susceptible to efavirenz with a mean effective concentration of 5.9 ± 4.5 nM, and RT-SHIV variants selected with efavirenz in cell culture displayed 600-fold-reduced susceptibility. The efavirenz-resistant mutants of RT-SHIV had mutations in RT similar to those of HIV-1 variants that were selected under similar conditions. Efavirenz monotherapy of RT-SHIV-infected macaques produced a 1.82-log-unit decrease in plasma viral-RNA levels after 1 week. The virus load rebounded within 3 weeks in one treated animal and more slowly in a second animal. Virus isolated from these two animals contained the K103N and Y188C or Y188L mutations. The RT-SHIV-rhesus macaque model may prove useful for studies of antiretroviral drug combinations that include efavirenz.

scholarly journals The Conserved Carboxy Terminus of the Capsid Domain of Human Immunodeficiency Virus Type 1 Gag Protein Is Important for Virion Assembly and Release

2004 ◽  
Vol 78 (18) ◽  
pp. 9675-9688 ◽  
Author(s):  
Daniel Melamed ◽  
Michal Mark-Danieli ◽  
Michal Kenan-Eichler ◽  
Osnat Kraus ◽  
Asher Castiel ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Hinge Region ◽  
Virion Assembly ◽  
C Terminus ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Ca Protein

ABSTRACT The retroviral Gag precursor plays an important role in the assembly of virion particles. The capsid (CA) protein of the Gag molecule makes a major contribution to this process. In the crystal structure of the free CA protein of the human immunodeficiency virus type 1 (HIV-1), 11 residues of the C terminus were found to be unstructured, and to date no information exists on the structure of these residues in the context of the Gag precursor molecule. We performed phylogenetic analysis and demonstrated a high degree of conservation of these 11 amino acids. Deletion of this cluster or introduction of various point mutations into these residues resulted in significant impairment of particle infectivity. In this cluster, two putative structural regions were identified, residues that form a hinge region (353-VGGP-356) and those that contribute to an α-helix (357-GHKARVL-363). Overall, mutations in these regions resulted in inhibition of virion production, but mutations in the hinge region demonstrated the most significant reduction. Although all the Gag mutants appeared to have normal Gag-Gag and Gag-RNA interactions, the hinge mutants were characterized by abnormal formation of cytoplasmic Gag complexes. Gag proteins with mutations in the hinge region demonstrated normal membrane association but aberrant rod-like membrane structures. More detailed analysis of these structures in one of the mutants demonstrated abnormal trapped Gag assemblies. These data suggest that the conserved CA C terminus is important for HIV-1 virion assembly and release and define a putative target for drug design geared to inhibit the HIV-1 assembly process.

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