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Harel S, Altaras Y, Nachmias D, Rotem-Dai N, Dvilansky I, Elia N, Rousso I. Analysis of individual HIV-1 budding event using fast AFM reveals a multiplexed role for VPS4. Biophys J 2022; 121:4229-4238. [PMID: 36042696 PMCID: PMC9674973 DOI: 10.1016/j.bpj.2022.08.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 08/15/2022] [Accepted: 08/24/2022] [Indexed: 11/18/2022] Open
Abstract
The assembly and budding of newly formed human immunodeficiency virus-1 (HIV-1) particles occur at the plasma membrane of infected cells. Although the molecular basis for viral budding has been studied extensively, investigation of its spatiotemporal characteristics has been limited by the small dimensions (∼100 nm) of HIV particles and the fast kinetics of the process (a few minutes from bud formation to virion release). Here we applied ultra-fast atomic force microscopy to achieve real-time visualization of individual HIV-1 budding events from wild-type (WT) cell lines as well as from mutated lines lacking vacuolar protein sorting-4 (VPS4) or visceral adipose tissue-1 protein (VTA1). Using single-particle analysis, we show that HIV-1 bud formation follows two kinetic pathways (fast and slow) with each composed of three distinct phases (growth, stationary, decay). Notably, approximately 38% of events did not result in viral release and were characterized by the formation of short (rather than tall) particles that slowly decayed back into the cell membrane. These non-productive events became more abundant in VPS4 knockout cell lines. Strikingly, the absence of VPS4B, rather than VPS4A, increased the production of short viral particles, suggesting a role for VPS4B in earlier stages of HIV-1 budding than traditionally thought.
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Affiliation(s)
- Shimon Harel
- Department of Physiology and Cell Biology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Yarin Altaras
- Department of Life Sciences and NIBN, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Dikla Nachmias
- Department of Life Sciences and NIBN, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Noa Rotem-Dai
- Department of Physiology and Cell Biology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Inbar Dvilansky
- Department of Life Sciences and NIBN, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Natalie Elia
- Department of Life Sciences and NIBN, Ben-Gurion University of the Negev, Beer Sheva, Israel.
| | - Itay Rousso
- Department of Physiology and Cell Biology, Ben-Gurion University of the Negev, Beer Sheva, Israel.
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Monette A, Niu M, Nijhoff Asser M, Gorelick RJ, Mouland AJ. Scaffolding viral protein NC nucleates phase separation of the HIV-1 biomolecular condensate. Cell Rep 2022; 40:111251. [PMID: 36001979 DOI: 10.1016/j.celrep.2022.111251] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 06/20/2022] [Accepted: 08/01/2022] [Indexed: 11/26/2022] Open
Abstract
Membraneless biomolecular condensates (BMCs) contribute to the replication of a growing number of viruses but remain to be functionally characterized. Previously, we demonstrated that pan-retroviral nucleocapsid (NC) proteins phase separated into condensates regulating virus assembly. Here we discover that intrinsically disordered human immunodeficiency virus-type 1 (HIV-1) core proteins condense with the viral genomic RNA (vRNA) to assemble as BMCs attaining a geometry characteristic of viral reverse transcription complexes. We explore the predisposition, mechanisms, and pharmacologic sensitivity of HIV-1 core BMCs in living cells. HIV-1 vRNA-interacting NC condensates were found to be scaffolds onto which client capsid, reverse transcriptase, and integrase condensates assemble. HIV-1 core BMCs exhibit fundamental characteristics of BMCs and are drug-sensitive. Lastly, protease-mediated maturation of Gag and Gag-Pol precursor proteins yield abundant and visible BMCs in cells. This study redefines HIV-1 core components as fluid BMCs and advances our understanding of the nature of viral cores during ingress.
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Affiliation(s)
- Anne Monette
- HIV-1 RNA Trafficking Lab, Lady Davis Institute at the Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada.
| | - Meijuan Niu
- HIV-1 RNA Trafficking Lab, Lady Davis Institute at the Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada
| | - Maya Nijhoff Asser
- HIV-1 RNA Trafficking Lab, Lady Davis Institute at the Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada; Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada
| | - Robert J Gorelick
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21701, USA
| | - Andrew J Mouland
- HIV-1 RNA Trafficking Lab, Lady Davis Institute at the Jewish General Hospital, Montreal, Quebec H3T 1E2, Canada; Department of Microbiology and Immunology, McGill University, Montreal, Quebec H3A 2B4, Canada; Department of Medicine, McGill University, Montreal, Quebec H4A 3J1, Canada.
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Rousso I, Deshpande A. Applications of Atomic Force Microscopy in HIV-1 Research. Viruses 2022; 14:v14030648. [PMID: 35337055 PMCID: PMC8955997 DOI: 10.3390/v14030648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 12/10/2022] Open
Abstract
Obtaining an understanding of the mechanism underlying the interrelations between the structure and function of HIV-1 is of pivotal importance. In previous decades, this mechanism was addressed extensively in a variety of studies using conventional approaches. More recently, atomic force microscopy, which is a relatively new technique with unique capabilities, has been utilized to study HIV-1 biology. Atomic force microscopy can generate high-resolution images at the nanometer-scale and analyze the mechanical properties of individual HIV-1 virions, virus components (e.g., capsids), and infected live cells under near-physiological environments. This review describes the working principles and various imaging and analysis modes of atomic force microscopy, and elaborates on its distinctive contributions to HIV-1 research in areas such as mechanobiology and the physics of infection.
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How HIV-1 Gag Manipulates Its Host Cell Proteins: A Focus on Interactors of the Nucleocapsid Domain. Viruses 2020; 12:v12080888. [PMID: 32823718 PMCID: PMC7471995 DOI: 10.3390/v12080888] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 08/06/2020] [Accepted: 08/10/2020] [Indexed: 12/27/2022] Open
Abstract
The human immunodeficiency virus (HIV-1) polyprotein Gag (Group-specific antigen) plays a central role in controlling the late phase of the viral lifecycle. Considered to be only a scaffolding protein for a long time, the structural protein Gag plays determinate and specific roles in HIV-1 replication. Indeed, via its different domains, Gag orchestrates the specific encapsidation of the genomic RNA, drives the formation of the viral particle by its auto-assembly (multimerization), binds multiple viral proteins, and interacts with a large number of cellular proteins that are needed for its functions from its translation location to the plasma membrane, where newly formed virions are released. Here, we review the interactions between HIV-1 Gag and 66 cellular proteins. Notably, we describe the techniques used to evidence these interactions, the different domains of Gag involved, and the implications of these interactions in the HIV-1 replication cycle. In the final part, we focus on the interactions involving the highly conserved nucleocapsid (NC) domain of Gag and detail the functions of the NC interactants along the viral lifecycle.
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Stauffer S, Rahman SA, de Marco A, Carlson LA, Glass B, Oberwinkler H, Herold N, Briggs JAG, Müller B, Grünewald K, Kräusslich HG. The nucleocapsid domain of Gag is dispensable for actin incorporation into HIV-1 and for association of viral budding sites with cortical F-actin. J Virol 2014; 88:7893-903. [PMID: 24789788 PMCID: PMC4097806 DOI: 10.1128/jvi.00428-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 04/24/2014] [Indexed: 12/24/2022] Open
Abstract
Actin and actin-binding proteins are incorporated into HIV-1 particles, and F-actin has been suggested to bind the NC domain in HIV-1 Gag. Furthermore, F-actin has been frequently observed in the vicinity of HIV-1 budding sites by cryo-electron tomography (cET). Filamentous structures emanating from viral buds and suggested to correspond to actin filaments have been observed by atomic force microscopy. To determine whether the NC domain of Gag is required for actin association with viral buds and for actin incorporation into HIV-1, we performed comparative analyses of virus-like particles (VLPs) obtained by expression of wild-type HIV-1 Gag or a Gag variant where the entire NC domain had been replaced by a dimerizing leucine zipper [Gag(LZ)]. The latter protein yielded efficient production of VLPs with near-wild-type assembly kinetics and size and exhibited a regular immature Gag lattice. Typical HIV-1 budding sites were detected by using cET in cells expressing either Gag or Gag(LZ), and no difference was observed regarding the association of buds with the F-actin network. Furthermore, actin was equally incorporated into wild-type HIV-1 and Gag- or Gag(LZ)-derived VLPs, with less actin per particle observed than had been reported previously. Incorporation appeared to correlate with the relative intracellular actin concentration, suggesting an uptake of cytosol rather than a specific recruitment of actin. Thus, the NC domain in HIV-1 Gag does not appear to have a role in actin recruitment or actin incorporation into HIV-1 particles. Importance: HIV-1 particles bud from the plasma membrane, which is lined by a network of actin filaments. Actin was found to interact with the nucleocapsid domain of the viral structural protein Gag and is incorporated in significant amounts into HIV-1 particles, suggesting that it may play an active role in virus release. Using electron microscopy techniques, we previously observed bundles of actin filaments near HIV-1 buds, often seemingly in contact with the Gag layer. Here, we show that this spatial association is observed independently of the proposed actin-binding domain of HIV-1. The absence of this domain also did not affect actin incorporation and had a minor effect on the viral assembly rate. Furthermore, actin was not enriched in the virus compared to the average levels in the respective producing cell. Our data argue against a specific recruitment of actin to HIV-1 budding sites by the nucleocapsid domain of Gag.
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Affiliation(s)
- Sarah Stauffer
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Sheikh Abdul Rahman
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Alex de Marco
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany Molecular Medicine Partnership Unit, Heidelberg, Germany
| | - Lars-Anders Carlson
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Bärbel Glass
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Heike Oberwinkler
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Nikolas Herold
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - John A G Briggs
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany Molecular Medicine Partnership Unit, Heidelberg, Germany
| | - Barbara Müller
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Kay Grünewald
- Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany Molecular Medicine Partnership Unit, Heidelberg, Germany
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Guo J, Xu X, Rasheed TK, Yoder A, Yu D, Liang H, Yi F, Hawley T, Jin T, Ling B, Wu Y. Genistein interferes with SDF-1- and HIV-mediated actin dynamics and inhibits HIV infection of resting CD4 T cells. Retrovirology 2013; 10:62. [PMID: 23782904 PMCID: PMC3693989 DOI: 10.1186/1742-4690-10-62] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 06/10/2013] [Indexed: 11/23/2022] Open
Abstract
Background Binding of HIV to the chemokine coreceptor CXCR4 mediates viral fusion and signal transduction that promotes actin dynamics critical for HIV infection of blood resting CD4 T cells. It has been suggested that this gp120-mediated actin activity resembles the chemotactic actin dynamics mediated by chemokines such as SDF-1. To determine whether inhibiting SDF-1-mediated chemotactic activity can also inhibit HIV infection, we screened several inhibitors known to reduce SDF-1-mediated chemotaxis of T cells. Results We found that a tyrosine kinase inhibitor, genistein, inhibited both SDF-1-mediated chemotaxis and HIV infection of resting CD4 T cells. Genistein was also found to interfere with SDF-1- and HIV-mediated actin dynamics in CD4 T cells. This reduction in actin activity correlates with genistein-mediated inhibition of viral DNA accumulation in resting CD4 T cells. In addition, we also tested two other tyrosine kinase inhibitors, sunitinib and AG1478. Sunitinib, but not AG1478, inhibited HIV infection of resting CD4 T cells. We further tested the safety of genistein in 3 Chinese rhesus macaques (Macaca mulatta), and each animal was given a monotherapy of genistein at 10 mg/kg orally for 12 weeks. No adverse drug effects were observed in these animals. Conclusions Our results suggest that novel therapeutic strategies can be developed based on targeting cellular proteins involved in HIV-dependent signaling. This approach can interfere with HIV-mediated actin dynamics and inhibit HIV infection.
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Affiliation(s)
- Jia Guo
- National Center for Biodefense and Infectious Diseases, Department of Molecular and Microbiology, George Mason University, Manassas VA 20110, USA.
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Xu X, Guo J, Vorster P, Wu Y. Involvement of LIM kinase 1 in actin polarization in human CD4 T cells. Commun Integr Biol 2012; 5:381-3. [PMID: 23060964 PMCID: PMC3460845 DOI: 10.4161/cib.20165] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Chemokine binding to cognate receptors induces actin dynamics that are a major driving force for T cell migration and chemotactic motility. HIV-1 binding to the chemokine coreceptor CXCR4 initiates chemotactic signaling, mimicking chemokine-induced actin dynamics to facilitate infection processes such as entry, early DNA synthesis, and nuclear migration. Recently, we identified that HIV-triggered early actin polymerization is mediated through the Rac1-PAK1/2-LIMK1-cofilin pathway. Inhibition of LIMK1 (LIM domain kinase 1), a kinase phosphorylating cofilin, through shRNA knockdown decreases actin polymerization and T cell chemotaxis toward SDF-1. The LIMK1 knockdown T cells also supported lower viral entry, DNA synthesis and nuclear migration, suggesting a critical role of LIMK1-mediated actin dynamics in the initiation of HIV-1 infection. Surprisingly, LIMK1 knockdown in CEM-SS T cells did not lead to an overall change in the ratio of phospho-cofilin to total cofilin although there was a measurable decrease in the amount of actin filaments in cells. The decrease in filamentous actin in LIMK1 knockdown cells was found to mainly occur in polarized cap region rich in F-actin. These results suggest that LIMK1 may be involved in spontaneous actin polarization in transformed T cells. The inhibition of T cell chemotaxis by LIMK1 knockdown likely result from inhibition of localized LIMK1 activation and cofilin phosphorylation that are required for polarized actin polymerization for directional cell migration. The inhibition of HIV-1 infection by LIMK1 knockdown may also result from the decrease of actin-rich membrane protrusions that may be preferred viral entry sites in T cells.
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Affiliation(s)
- Xuehua Xu
- Chemotaxis Signal Section; Laboratory of Immunogenetics; National Institute of Allergy and Infectious Disease; NIH; Rockville, MD USA
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Spear M, Guo J, Wu Y. The trinity of the cortical actin in the initiation of HIV-1 infection. Retrovirology 2012; 9:45. [PMID: 22640593 PMCID: PMC3416652 DOI: 10.1186/1742-4690-9-45] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 05/03/2012] [Indexed: 12/16/2022] Open
Abstract
For an infecting viral pathogen, the actin cortex inside the host cell is the first line of intracellular components that it encounters. Viruses devise various strategies to actively engage or circumvent the actin structure. In this regard, the human immunodeficiency virus-1 (HIV-1) exemplifies command of cellular processes to take control of actin dynamics for the initiation of infection. It has becomes increasingly evident that cortical actin presents itself both as a barrier to viral intracellular migration and as a necessary cofactor that the virus must actively engage, particularly, in the infection of resting CD4 blood T cells, the primary targets of HIV-1. The coercion of this most fundamental cellular component permits infection by facilitating entry, reverse transcription, and nuclear migration, three essential processes for the establishment of viral infection and latency in blood T cells. It is the purpose of this review to examine, in detail, the manifestation of viral dependence on the actin cytoskeleton, and present a model of how HIV utilizes actin dynamics to initiate infection.
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Affiliation(s)
- Mark Spear
- National Center for Biodefense and Infectious Diseases, Department of Molecular and Microbiology, George Mason University, Manassas, VA 20110, USA
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Warrilow D, Tachedjian G, Harrich D. Maturation of the HIV reverse transcription complex: putting the jigsaw together. Rev Med Virol 2010; 19:324-37. [PMID: 19750561 DOI: 10.1002/rmv.627] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Upon HIV attachment, fusion and entry into the host cell cytoplasm, the viral core undergoes rearrangement to become the mature reverse transcription complex (RTC). Reduced infectivity of viral deletion mutants of the core proteins, capsid and negative factor (Nef), can be complemented by vesicular stomatitis virus (VSV) pseudotyping suggesting a role for these viral proteins in a common event immediately post-entry. This event may be necessary for correct trafficking of the early complex. Enzymatic activation of the complex occurs either before or during RTC maturation, and may be dependent on the presence of deoxynucleotides in the host cell. The RTC initially becomes enlarged immediately after entry, which is followed by a decrease in its sedimentation rate consistent with core uncoating. Several HIV proteins associated with the RTC and recently identified host-cell proteins are important for reverse transcription while genome-wide siRNA knockdown studies have identified additional host cell factors that may be required for reverse transcription. Determining precisely how these proteins assist the RTC function needs to be addressed.
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Affiliation(s)
- David Warrilow
- Division of Infectious Diseases, Queensland Institute of Medical Research, Brisbane, Queensland 4006, Australia.
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Yu D, Wang W, Yoder A, Spear M, Wu Y. The HIV envelope but not VSV glycoprotein is capable of mediating HIV latent infection of resting CD4 T cells. PLoS Pathog 2009; 5:e1000633. [PMID: 19851458 PMCID: PMC2760144 DOI: 10.1371/journal.ppat.1000633] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Accepted: 09/25/2009] [Indexed: 01/14/2023] Open
Abstract
HIV fusion and entry into CD4 T cells are mediated by two receptors, CD4 and CXCR4. This receptor requirement can be abrogated by pseudotyping the virion with the vesicular stomatitis virus glycoprotein (VSV-G) that mediates viral entry through endocytosis. The VSV-G-pseudotyped HIV is highly infectious for transformed cells, although the virus circumvents the viral receptors and the actin cortex. In HIV infection, gp120 binding to the receptors also transduces signals. Recently, we demonstrated a unique requirement for CXCR4 signaling in HIV latent infection of blood resting CD4 T cells. Thus, we performed parallel studies in which the VSV-G-pseudotyped HIV was used to infect both transformed and resting T cells in the absence of coreceptor signaling. Our results indicate that in transformed T cells, the VSV-G-pseudotyping results in lower viral DNA synthesis but a higher rate of nuclear migration. However, in resting CD4 T cells, only the HIV envelope-mediated entry, but not the VSV-G-mediated endocytosis, can lead to viral DNA synthesis and nuclear migration. The viral particles entering through the endocytotic pathway were destroyed within 1–2 days. These results indicate that the VSV-G-mediated endocytotic pathway, although active in transformed cells, is defective and is not a pathway that can establish HIV latent infection of primary resting T cells. Our results highlight the importance of the genuine HIV envelope and its signaling capacity in the latent infection of blood resting T cells. These results also call for caution on the endocytotic entry model of HIV-1, and on data interpretation where the VSV-G-pseudotyped HIV was used for identifying HIV restriction factors in resting T cells. While receptor-mediated viral endocytosis or fusion with the cell membrane can be achieved through multiple surface molecules, the repetitious selection of two chemokine receptors, CCR5 or CXCR4, as the main HIV entry coreceptor implies an urgent viral need to exploit the chemotactic process in the immune system. Cytoskeletal rearrangement and cell migration are the primary consequences of chemotactic signaling. Nevertheless, previously published data demonstrated that depriving the virus of its signaling ability conferred higher infectivity through VSV-G-mediated endocytotic entry in transformed cells. We revisited the issue of chemokine coreceptor signaling and the role of cortical actin in HIV-1 latent infection of resting CD4 T cells, in which the virus can establish latency with a potential for productive replication upon T cell activation. Our results confirmed that only the genuine HIV-1 envelope protein, but not VSV-G, is capable of mediating latent infection of resting CD4 T cells. These findings highlight the importance of the HIV envelope and its signaling capacity in HIV infection of its natural target cells.
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Affiliation(s)
- Dongyang Yu
- Department of Molecular and Microbiology, George Mason University, Manassas, Virginia, United States of America
| | - Weifeng Wang
- Department of Molecular and Microbiology, George Mason University, Manassas, Virginia, United States of America
| | - Alyson Yoder
- Department of Molecular and Microbiology, George Mason University, Manassas, Virginia, United States of America
| | - Mark Spear
- Department of Molecular and Microbiology, George Mason University, Manassas, Virginia, United States of America
| | - Yuntao Wu
- Department of Molecular and Microbiology, George Mason University, Manassas, Virginia, United States of America
- * E-mail:
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Development of a platelet-activating factor antagonist for HIV-1 associated neurocognitive disorders. J Neuroimmunol 2009; 213:47-59. [PMID: 19541372 DOI: 10.1016/j.jneuroim.2009.06.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 05/27/2009] [Accepted: 06/01/2009] [Indexed: 02/07/2023]
Abstract
The neuroregulatory activities of PMS-601, a platelet activating factor antagonist, were investigated in laboratory and animal models of HIV-1 encephalitis (HIVE). For the former, PMS-601 reduced monocyte-derived macrophage pro-inflammatory secretions, multinucleated giant cell (MGC) formation, and neuronal loss independent of antiretroviral responses. PMS-601 treatment of HIVE severe combined immunodeficient mice showed reduced microgliosis, MGCs and neurodegeneration. These observations support the further development of PMS-601 as an adjunctive therapy for HIV-1 associated neurocognitive disorders.
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Frascaroli G, Varani S, Blankenhorn N, Pretsch R, Bacher M, Leng L, Bucala R, Landini MP, Mertens T. Human cytomegalovirus paralyzes macrophage motility through down-regulation of chemokine receptors, reorganization of the cytoskeleton, and release of macrophage migration inhibitory factor. THE JOURNAL OF IMMUNOLOGY 2009; 182:477-88. [PMID: 19109179 DOI: 10.4049/jimmunol.182.1.477] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Macrophages contribute to host defense and to the maintenance of immune homeostasis. Conversely, they are important targets of human cytomegalovirus (HCMV), a herpesvirus that has evolved many strategies to modulate the host immune response. Because an efficient macrophage trafficking is required for triggering an adequate immune response, we investigated the effects exerted by HCMV infection on macrophage migratory properties. By using endotheliotropic strains of HCMV, we obtained high rates of productively infected human monocyte-derived macrophages (MDM). Twenty-four hours after infection, MDM showed reduced polar morphology and became unable to migrate in response to inflammatory and lymphoid chemokines, bacterial products and growth factors, despite being viable and metabolically active. Although chemotactic receptors were only partially affected, HCMV induced a dramatic reorganization of the cytoskeleton characterized by rupture of the microtubular network, stiffness of the actin fibers, and collapse of the podosomes. Furthermore, supernatants harvested from infected MDM contained high amounts of macrophage migration inhibitory factor (MIF) and were capable to block the migration of neighboring uninfected MDM. Because immunodepletion of MIF from the conditioned medium completely restored MDM chemotaxis, we could show for the first time a functional role of MIF as an inhibitor of macrophage migration in the context of HCMV infection. Our findings reveal that HCMV uses different mechanisms to interfere with movement and positioning of macrophages, possibly leading to an impairment of antiviral responses and to an enhancement of the local inflammation.
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13
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Jolly C, Mitar I, Sattentau QJ. Requirement for an intact T-cell actin and tubulin cytoskeleton for efficient assembly and spread of human immunodeficiency virus type 1. J Virol 2007; 81:5547-60. [PMID: 17360745 PMCID: PMC1900271 DOI: 10.1128/jvi.01469-06] [Citation(s) in RCA: 162] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) infection of CD4(+) T cells leads to the production of new virions that assemble at the plasma membrane. Gag and Env accumulate in the context of lipid rafts at the inner and outer leaflets of the plasma membrane, respectively, forming polarized domains from which HIV-1 buds. HIV-1 budding can result in either release of cell-free virions or direct cell-cell spread via a virological synapse (VS). The recruitment of Gag and Env to these plasma membrane caps in T cells is poorly understood but may require elements of the T-cell secretory apparatus coordinated by the cytoskeleton. Using fixed-cell immunofluorescence labeling and confocal microscopy, we observed a high percentage of HIV-1-infected T cells with polarized Env and Gag in capped, lipid raft-like assembly domains. Treatment of infected T cells with inhibitors of actin or tubulin remodeling disrupted Gag and Env compartmentalization within the polarized raft-like domains. Depolymerization of the actin cytoskeleton reduced Gag release and viral infectivity, and actin and tubulin inhibitors reduced Env incorporation into virions. Live- and fixed-cell confocal imaging and assay of de novo DNA synthesis by real-time PCR allowed quantification of HIV-1 cell-cell transfer. Inhibition of actin and tubulin remodeling in infected cells interfered with cell-cell spread across a VS and reduced new viral DNA synthesis. Based on these data, we propose that HIV-1 requires both actin and tubulin components of the T-cell cytoskeleton to direct its assembly and budding and to elaborate a functional VS.
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Affiliation(s)
- Clare Jolly
- The Sir William Dunn School of Pathology, The University of Oxford, Oxford OX1 3RE, United Kingdom.
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14
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Wahl SM, Greenwell-Wild T, Vázquez N. HIV accomplices and adversaries in macrophage infection. J Leukoc Biol 2006; 80:973-83. [PMID: 16908514 DOI: 10.1189/jlb.0306130] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cell surface and intracellular proteins in macrophages influence various steps in the life cycle of lentiviruses. Characterization of these restriction and/or cofactors is essential to understanding how macrophages become unwitting HIV hosts and in fact, can coexist with a heavy viral burden. Although many of the cellular pathways co-opted by HIV in macrophages mimic those seen in CD4+ T cells, emerging evidence reveals cellular constituents of the macrophage, which may be uniquely usurped by HIV. For example, in addition to CD4 and CCR5, membrane annexin II facilitates early steps in infection of macrophages, but not in T cells. Blockade of this pathway effectively diminishes macrophage infection. Viral binding engages a macrophage-centric signaling pathway and a transcriptional profile, including genes such as p21, which benefit the virus. Once inside the cell, multiple host cell molecules are engaged to facilitate virus replication and assembly. Although the macrophage is an enabler, it also possesses innate antiviral mechanisms, including apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3G (APOBEC3) family DNA-editing enzymes to inhibit replication of HIV. Differential expression of these enzymes, which are largely neutralized by HIV to protect its rebirth, is associated with resistance or susceptibility to the virus. Higher levels of the cytidine deaminases endow potential HIV targets with a viral shield, and IFN-alpha, a natural inducer of macrophage APOBEC expression, renders macrophages tougher combatants to HIV infection. These and other manipulatable pathways may give the macrophage a fighting chance in its battle against the virus.
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Affiliation(s)
- Sharon M Wahl
- Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Building 30, Rm. 320, 30 Convent Dr., MSC 4352, Bethesda, MD 20892-4352, USA.
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15
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Jensen HL. Herpes simplex virus type 1 morphogenesis and virus-cell interactions: significance of cytoskeleton and methodological aspects. APMIS 2006:7-55. [PMID: 16930175 DOI: 10.1111/j.1600-0463.2006.apm_v114_s119.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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16
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Poole E, Strappe P, Mok HP, Hicks R, Lever AML. HIV-1 Gag-RNA interaction occurs at a perinuclear/centrosomal site; analysis by confocal microscopy and FRET. Traffic 2005; 6:741-55. [PMID: 16101678 DOI: 10.1111/j.1600-0854.2005.00312.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The Gag polyprotein is the major structural protein of human immunodeficiency virus-1 (HIV-1) constituting the viral core. Between translation on cytoplasmic polysomes and assembly into viral particles at the plasma membrane, it specifically captures the RNA genome of the virus through binding RNA structural motifs (packaging signals -Psi) in the RNA. RNA is believed to be a structural facilitator of Gag assembly. Using a combined approach of immunofluorescence detection of Gag protein and in situ hybridisation detection of viral genomic RNA, we demonstrate that Gag protein colocalises early after expression with Psi+ RNA in the perinuclear region and also colocalises with centrioles. Colocalised RNA and protein subsequently traffic through the cytoplasm to the plasma membrane of the cell. Gag expressed from Psi- RNA diffuses throughout the cell. It is not found at centrioles and shows delayed cytoplasmic colocalisation with the RNA genome. RNA capture through Psi does not influence binding of Gag to microfilaments. Gag does not bind to tubulin during export. The presence of the packaging signal may coordinate capture of Psi+ RNA by Gag protein at the centrosome followed by their combined transport to the site of budding. HIV-1 Psi thus acts as a subcellular localisation signal as well as a high-affinity-binding site for Gag.
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Affiliation(s)
- Emma Poole
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge, CB2 2QQ, UK
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17
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Audoly G, Popoff MR, Gluschankof P. Involvement of a small GTP binding protein in HIV-1 release. Retrovirology 2005; 2:48. [PMID: 16080789 PMCID: PMC1190218 DOI: 10.1186/1742-4690-2-48] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2005] [Accepted: 08/04/2005] [Indexed: 12/22/2022] Open
Abstract
Background There is evidence suggesting that actin binding to HIV-1 encoded proteins, or even actin dynamics themselves, might play a key role in virus budding and/or release from the infected cell. A crucial step in the reorganisation of the actin cytoskeleton is the engagement of various different GTP binding proteins. We have thus studied the involvement of GTP-binding proteins in the final steps of the HIV-1 viral replication cycle. Results Our results demonstrate that virus production is abolished when cellular GTP binding proteins involved in actin polymerisation are inhibited with specific toxins. Conclusion We propose a new HIV budding working model whereby Gag interactions with pre-existing endosomal cellular tracks as well as with a yet non identified element of the actin polymerisation pathway are required in order to allow HIV-1 to be released from the infected cell.
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Affiliation(s)
- Gilles Audoly
- Unité des Rickettsies, CNRS UMR6020, Faculté de Médecine, 27 bd Jean Moulin, 13385 Marseille cedex 05, IFR48, France
| | - Michel R Popoff
- Unité des Bactéries Anaérobies et Toxines, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France
| | - Pablo Gluschankof
- Unité des Rickettsies, CNRS UMR6020, Faculté de Médecine, 27 bd Jean Moulin, 13385 Marseille cedex 05, IFR48, France
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18
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Matarrese P, Malorni W. Human immunodeficiency virus (HIV)-1 proteins and cytoskeleton: partners in viral life and host cell death. Cell Death Differ 2005; 12 Suppl 1:932-41. [PMID: 15818415 DOI: 10.1038/sj.cdd.4401582] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cytoskeletal components play a major role in the human immunodeficiency virus-1 (HIV-1) infection. A wide variety of molecules belonging to the microfilament system, including actin filaments and actin binding proteins, as well as microtubules have a key role in regulating both cell life and death. Cell shape maintenance, cell polarity and cell movements as well as cytoplasmic trafficking of molecules determining cell fate, including apoptosis, are in fact instructed by the cytoskeleton components. HIV infection and viral particle production seem to be controlled by cytoskeleton as well. Furthermore, HIV-associated apoptosis failure can also be regulated by the actin network function. In fact, HIV protein gp120 is able to induce cytoskeleton-driven polarization, thus sensitizing T cells to CD95/Fas-mediated apoptosis. The microfilament system seems thus to be a sort of cytoplasmic supervisor of the viral particle, the host cell and the bystander cell's very fate.
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Affiliation(s)
- P Matarrese
- Section of Cell Aging and Degeneration, Department of Drug Research and Evaluation, Istituto Superiore di Sanitá, Viale Regina Elena 299, Rome, Italy
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Nisole S, Saïb A. Early steps of retrovirus replicative cycle. Retrovirology 2004; 1:9. [PMID: 15169567 PMCID: PMC421752 DOI: 10.1186/1742-4690-1-9] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2004] [Accepted: 05/14/2004] [Indexed: 12/28/2022] Open
Abstract
During the last two decades, the profusion of HIV research due to the urge to identify new therapeutic targets has led to a wealth of information on the retroviral replication cycle. However, while the late stages of the retrovirus life cycle, consisting of virus replication and egress, have been partly unraveled, the early steps remain largely enigmatic. These early steps consist of a long and perilous journey from the cell surface to the nucleus where the proviral DNA integrates into the host genome. Retroviral particles must bind specifically to their target cells, cross the plasma membrane, reverse-transcribe their RNA genome, while uncoating the cores, find their way to the nuclear membrane and penetrate into the nucleus to finally dock and integrate into the cellular genome. Along this journey, retroviruses hijack the cellular machinery, while at the same time counteracting cellular defenses. Elucidating these mechanisms and identifying which cellular factors are exploited by the retroviruses and which hinder their life cycle, will certainly lead to the discovery of new ways to inhibit viral replication and to improve retroviral vectors for gene transfer. Finally, as proven by many examples in the past, progresses in retrovirology will undoubtedly also provide some priceless insights into cell biology.
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Affiliation(s)
- Sébastien Nisole
- Division of Virology, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
| | - Ali Saïb
- CNRS UPR9051, Hôpital Saint-Louis, 1 Avenue Claude Vellefaux, 75475 Paris cedex 10, France
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20
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Abstract
The assembly of HIV is relatively poorly investigated when compared with the process of virus entry. Yet a detailed understanding of the mechanism of assembly is fundamental to our knowledge of the complete life cycle of this virus and also has the potential to inform the development of new antiviral strategies. The repeated multiple interaction of the basic structural unit, Gag, might first appear to be little more than concentration dependent self-assembly but the precise mechanisms emerging for HIV are far from simple. Gag interacts not only with itself but also with host cell lipids and proteins in an ordered and stepwise manner. It binds both the genomic RNA and the virus envelope protein and must do this at an appropriate time and place within the infected cell. The assembled virus particle must successfully release from the cell surface and, whilst being robust enough for transmission between hosts, must nonetheless be primed for rapid disassembly when infection occurs. Our current understanding of these processes and the domains of Gag involved at each stage is the subject of this review.
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Affiliation(s)
- Catherine S Adamson
- School of Animal and Microbial Sciences, The University of Reading, Reading RG6 6AJ, UK.
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21
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Chen C, Weisz OA, Stolz DB, Watkins SC, Montelaro RC. Differential effects of actin cytoskeleton dynamics on equine infectious anemia virus particle production. J Virol 2004; 78:882-91. [PMID: 14694119 PMCID: PMC368807 DOI: 10.1128/jvi.78.2.882-891.2004] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Retrovirus assembly and budding involve a highly dynamic and concerted interaction of viral and cellular proteins. Previous studies have shown that retroviral Gag proteins interact with actin filaments, but the significance of these interactions remains to be defined. Using equine infectious anemia virus (EIAV), we now demonstrate differential effects of cellular actin dynamics at distinct stages of retrovirus assembly and budding. First, virion production was reduced when EIAV-infected cells were treated with phallacidin, a cell-permeable reagent that stabilizes actin filaments by slowing down their depolymerization. Confocal microscopy confirmed that the inhibition of EIAV production correlated temporally over several days with the incorporation dynamics of phallacidin into the actin cytoskeleton. Although the overall structure of the actin cytoskeleton and expression of viral protein appeared to be unaffected, phallacidin treatment dramatically reduced the amount of full-length Gag protein associated with the actin cytoskeleton. These data suggest that an association of full-length Gag proteins with de novo actin filaments might contribute to Gag assembly and budding. On the other hand, virion production was enhanced when EIAV-infected cells were incubated briefly (2 h) with the actin-depolymerizing drugs cytochalasin D and latrunculin B. Interestingly, the enhanced virion production induced by cytochalasin D required a functional late (L) domain, either the EIAV YPDL L-domain or the proline-rich L domains derived from human immunodeficiency virus type 1 or Rous sarcoma virus, respectively. Thus, depolymerization of actin filaments may be a common function mediated by retrovirus L domains during late stages of viral budding. Taken together, these observations indicate that dynamic actin polymerization and depolymerization may be associated with different stages of viral production.
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Affiliation(s)
- Chaoping Chen
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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23
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Dvorin JD, Malim MH. Intracellular trafficking of HIV-1 cores: journey to the center of the cell. Curr Top Microbiol Immunol 2003; 281:179-208. [PMID: 12932078 DOI: 10.1007/978-3-642-19012-4_5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
After entry into the cytoplasm, many diverse viruses, including both RNA and DNA viruses, require import into the nucleus and access to the cellular nuclear machinery for productive replication to proceed. Because diffusion through the crowded cytoplasmic environment is greatly restricted, most (if not all) of these viruses must first be actively transported from the site of cytoplasmic entry to the nuclear periphery (Luby-Phelps 2000; Lukacs et al. 2000; Sodeik 2000). Having reached the nucleus, viruses have evolved assorted methods to overcome the formidable physical barrier that is presented by the nuclear envelope. This review examines how these issues relate to human immunodeficiency virus type-1 (HIV-1) infection. Specifically, HIV-1 uncoating, cytoplasmic transport, and nuclear entry are addressed.
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Affiliation(s)
- J D Dvorin
- Department of Microbiology and Cell and Molecular Biology Graduate Group, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6148, USA
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24
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Abstract
Human immunodeficiency virus type-1 particles contain host proteins, both on their surface and interior. This review summarises the cellular proteins found in these virions and covers some of their potential roles in the viral life cycle and pathogenesis. For most proteins studied, their role and function are either unknown or in the hypothesis stage. This reflects the relatively recent emphasis given to these proteins by the HIV-1 field as well as the incomplete understanding of their function in the cell. The study of cellular proteins in HIV-1 promises to help us better understand the interaction of this virus with the cell, the immune system, and the whole human host as well as to shed light on the nature of AIDS and suggest more targets for therapeutic intervention. Finally, many of the cell systems themselves are still poorly understood. The extensive study of HIV-1 has already brought increased attention to the fields of immunology and vaccine science and, in the same way, might assist our understanding of the cellular pathways themselves.
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Affiliation(s)
- David E Ott
- AIDS Vaccine Program, SAIC-Frederick, Inc., National Cancer Institute at Frederick, Frederick, Maryland 21702-1201, USA.
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25
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Krogstad P, Geng YZ, Rey O, Canon J, Ibarrondo FJ, Ackerson B, Patel J, Aldovini A. Human immunodeficiency virus nucleocapsid protein polymorphisms modulate the infectivity of RNA packaging mutants. Virology 2002; 294:282-8. [PMID: 12009869 DOI: 10.1006/viro.2001.1319] [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: 11/22/2022]
Abstract
The nucleocapsid protein (NC) of retroviruses is involved in viral RNA packaging and initiation of reverse transcription. NC also mediates interactions between Gag and actin filaments. We found that residues at the amino terminus of NC are involved in efficient actin binding. When alanine residues were substituted for the arginine and lysine at positions 10 and 11 of NC in HIV(NL4-3), these mutations decreased actin binding but had only a modest effect on virus infectivity. A similarly mutated virus based on the HXB2 clone of HIV was not infectious. Mutational analysis of NL4-3 NC residues demonstrated that NC polymorphisms modulated the phenotype of NC mutations. Conservative amino acid differences between HXB2 and NL4-3 NCs were sufficient to explain the difference in infectivity of viruses carrying the R10A and K11A mutations.
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Affiliation(s)
- Paul Krogstad
- Department of Pediatrics, University of California, Los Angeles School of Medicine, Los Angeles, California 90095-1732, USA.
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