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Fert A, Richard J, Marchand LR, Planas D, Routy JP, Chomont N, Finzi A, Ancuta P. Metformin Enhances Antibody-Mediated Recognition of HIV-Infected CD4 + T-Cells by Decreasing Viral Release. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.15.580166. [PMID: 38464135 PMCID: PMC10925111 DOI: 10.1101/2024.02.15.580166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
The mechanistic target of rapamycin (mTOR) positively regulates multiple steps of the HIV-1 replication cycle. We previously reported that a 12-weeks supplementation of antiretroviral therapy (ART) with metformin, an indirect mTOR inhibitor used in type-2 diabetes treatment, reduced mTOR activation and HIV transcription in colon-infiltrating CD4+ T-cells, together with systemic inflammation in nondiabetic people with HIV-1 (PWH). Herein, we investigated the antiviral mechanisms of metformin. In a viral outgrowth assay performed with CD4+ T-cells from ART-treated PWH, and upon infection in vitro with replication-competent and VSV-G-pseudotyped HIV-1, metformin decreased virion release, but increased the frequency of productively infected CD4lowHIV-p24+ T-cells. These observations coincided with increased BST2/Tetherin (HIV release inhibitor) and Bcl-2 (pro-survival factor) expression, and improved recognition of productively infected T-cells by HIV-1 Envelope antibodies. Thus, metformin exerts pleiotropic effects on post-transcription/translation steps of the HIV-1 replication cycle and may be used to accelerate viral reservoir decay in ART-treated PWH.
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Affiliation(s)
- Augustine Fert
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Jonathan Richard
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Laurence Raymond Marchand
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
| | - Delphine Planas
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Jean-Pierre Routy
- Infectious Diseases and Immunity in Global Health Program, Research Institute, McGill University Health Centre, Montréal, QC, Canada
- Chronic Viral Illness Service, McGill University Health Centre, Montréal, QC, Canada
- Division of Hematology, McGill University Health Centre, Montreal, QC, Canada
| | - Nicolas Chomont
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Andrés Finzi
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Petronela Ancuta
- Centre de recherche du Centre hospitalier de l’Université de Montréal, Montréal, QC, H2X 0A9, Canada
- Département de microbiologie, infectiologie et immunologie, Faculté de médecine, Université de Montréal, Montréal, QC, H3C 3J7, Canada
- Lead Contact
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Olety B, Peters P, Wu Y, Usami Y, Göttlinger H. HIV-1 propagation is highly dependent on basal levels of the restriction factor BST2. SCIENCE ADVANCES 2021; 7:eabj7398. [PMID: 34714669 PMCID: PMC8555903 DOI: 10.1126/sciadv.abj7398] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 09/09/2021] [Indexed: 05/22/2023]
Abstract
BST2 is an interferon-inducible antiviral host protein antagonized by HIV-1 Vpu that entraps nascent HIV-1 virions on the cell surface. Unexpectedly, we find that HIV-1 lacking Nef can revert to full replication competence simply by losing the ability to antagonize BST2. Using gene editing together with cell sorting, we demonstrate that even the propagation of wild-type HIV-1 is strikingly dependent on BST2, including in primary human cells. HIV-1 propagation in BST2−/− populations can be fully rescued by exogenous BST2 irrespective of its capacity to signal and even by an artificial BST2-like protein that shares its virion entrapment activity but lacks sequence homology. Counterintuitively, our results reveal that HIV-1 propagation is critically dependent on basal levels of virion tethering by a key component of innate antiviral immunity.
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3
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Bednarska J, Pelchen-Matthews A, Novak P, Burden JJ, Summers PA, Kuimova MK, Korchev Y, Marsh M, Shevchuk A. Rapid formation of human immunodeficiency virus-like particles. Proc Natl Acad Sci U S A 2020; 117:21637-21646. [PMID: 32817566 PMCID: PMC7474690 DOI: 10.1073/pnas.2008156117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Understanding the molecular mechanisms involved in the assembly of viruses is essential for discerning how viruses transmit from cell to cell and host to host. Although molecular aspects of assembly have been studied for many viruses, we still have little information about these events in real time. Enveloped viruses such as HIV that assemble at, and bud from, the plasma membrane have been studied in some detail using live cell fluorescence imaging techniques; however, these approaches provide little information about the real-time morphological changes that take place as viral components come together to form individual virus particles. Here we used correlative scanning ion conductance microscopy and fluorescence confocal microscopy to measure the topological changes, together with the recruitment of fluorescently labeled viral proteins such as Gag and Vpr, during the assembly and release of individual HIV virus-like particles (VLPs) from the top, nonadherent surfaces of living cells. We show that 1) labeling of viral proteins with green fluorescent protein affects particle formation, 2) the kinetics of particle assembly on different plasma membrane domains can vary, possibly as a consequence of differences in membrane biophysical properties, and 3) VLPs budding from the top, unimpeded surface of cells can reach full size in 20 s and disappear from the budding site in 0.5 to 3 min from the moment curvature is initially detected, significantly faster than has been previously reported.
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Affiliation(s)
- Joanna Bednarska
- Department of Medicine, Imperial College London, W12 0NN London, United Kingdom
| | - Annegret Pelchen-Matthews
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E 6BT London, United Kingdom
| | - Pavel Novak
- Department of Medicine, Imperial College London, W12 0NN London, United Kingdom
- Functional Low-Dimensional Structures Laboratory, National University of Science and Technology "MISIS", 119991 Moscow, Russian Federation
| | - Jemima J Burden
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E 6BT London, United Kingdom
| | - Peter A Summers
- Molecular Sciences Research Hub, Department of Chemistry, Imperial College London, W12 0BZ London, United Kingdom
| | - Marina K Kuimova
- Molecular Sciences Research Hub, Department of Chemistry, Imperial College London, W12 0BZ London, United Kingdom
| | - Yuri Korchev
- Department of Medicine, Imperial College London, W12 0NN London, United Kingdom
- Nano Life Science Institute, Kanazawa University, 920-1192 Kanazawa, Japan
| | - Mark Marsh
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E 6BT London, United Kingdom;
| | - Andrew Shevchuk
- Department of Medicine, Imperial College London, W12 0NN London, United Kingdom;
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Giese S, Lawrence SP, Mazzon M, Nijmeijer BM, Marsh M. The Nef Protein of the Macrophage Tropic HIV-1 Strain AD8 Counteracts Human BST-2/Tetherin. Viruses 2020; 12:E459. [PMID: 32325729 PMCID: PMC7232323 DOI: 10.3390/v12040459] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 04/15/2020] [Accepted: 04/15/2020] [Indexed: 12/12/2022] Open
Abstract
Bone Marrow Stromal Cell Antigen 2 (BST-2)/tetherin inhibits the release of numerous enveloped viruses by physically tethering nascent particles to infected cells during the process of viral budding from the cell surface. Tetherin also restricts human immunodeficiency virus (HIV), and pandemic main (M) group HIV type 1s (HIV-1s) are thought to rely exclusively on their Vpu proteins to overcome tetherin-mediated restriction of virus release. However, at least one M group HIV-1 strain, the macrophage-tropic primary AD8 isolate, is unable to express Vpu due to a mutation in its translation initiation codon. Here, using primary monocyte-derived macrophages (MDMs), we show that AD8 Nef protein can compensate for the absence of Vpu and restore virus release to wild type levels. We demonstrate that HIV-1 AD8 Nef reduces endogenous cell surface tetherin levels, physically separating it from the site of viral budding, thus preventing HIV retention. Mechanistically, AD8 Nef enhances internalisation of the long isoform of human tetherin, leading to perinuclear accumulation of the restriction factor. Finally, we show that Nef proteins from other HIV strains also display varying degrees of tetherin antagonism. Overall, we show that M group HIV-1s can use an accessory protein other than Vpu to antagonise human tetherin.
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Affiliation(s)
| | | | | | | | - Mark Marsh
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK; (S.G.); (S.P.L.); (M.M.); (B.M.N.)
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Kelly JT, Human S, Alderman J, Jobe F, Logan L, Rix T, Gonçalves-Carneiro D, Leung C, Thakur N, Birch J, Bailey D. BST2/Tetherin Overexpression Modulates Morbillivirus Glycoprotein Production to Inhibit Cell-Cell Fusion. Viruses 2019; 11:v11080692. [PMID: 31366072 PMCID: PMC6723339 DOI: 10.3390/v11080692] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 07/16/2019] [Accepted: 07/20/2019] [Indexed: 12/28/2022] Open
Abstract
The measles virus (MeV), a member of the genus Morbillivirus, is an established pathogen of humans. A key feature of morbilliviruses is their ability to spread by virus-cell and cell-cell fusion. The latter process, which leads to syncytia formation in vitro and in vivo, is driven by the viral fusion (F) and haemagglutinin (H) glycoproteins. In this study, we demonstrate that MeV glycoproteins are sensitive to inhibition by bone marrow stromal antigen 2 (BST2/Tetherin/CD317) proteins. BST2 overexpression causes a large reduction in MeV syncytia expansion. Using quantitative cell-cell fusion assays, immunolabeling, and biochemistry we further demonstrate that ectopically expressed BST2 directly inhibits MeV cell-cell fusion. This restriction is mediated by the targeting of the MeV H glycoprotein, but not other MeV proteins. Using truncation mutants, we further establish that the C-terminal glycosyl-phosphatidylinositol (GPI) anchor of BST2 is required for the restriction of MeV replication in vitro and cell-cell fusion. By extending our study to the ruminant morbillivirus peste des petits ruminants virus (PPRV) and its natural host, sheep, we also confirm this is a broad and cross-species specific phenotype.
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Affiliation(s)
- James T Kelly
- Viral Glycoproteins Group, The Pirbright Institute, Ash Rd, Guildford, Surrey GU24 0NF, UK
| | - Stacey Human
- Viral Glycoproteins Group, The Pirbright Institute, Ash Rd, Guildford, Surrey GU24 0NF, UK
| | - Joseph Alderman
- Institute of Immunology and Immunotherapy, The University of Birmingham, Birmingham B15 2TT, UK
| | - Fatoumatta Jobe
- Viral Glycoproteins Group, The Pirbright Institute, Ash Rd, Guildford, Surrey GU24 0NF, UK
| | - Leanne Logan
- Viral Glycoproteins Group, The Pirbright Institute, Ash Rd, Guildford, Surrey GU24 0NF, UK
| | - Thomas Rix
- Viral Glycoproteins Group, The Pirbright Institute, Ash Rd, Guildford, Surrey GU24 0NF, UK
| | | | - Corwin Leung
- Institute of Immunology and Immunotherapy, The University of Birmingham, Birmingham B15 2TT, UK
| | - Nazia Thakur
- Viral Glycoproteins Group, The Pirbright Institute, Ash Rd, Guildford, Surrey GU24 0NF, UK
- Institute of Immunology and Immunotherapy, The University of Birmingham, Birmingham B15 2TT, UK
| | - Jamie Birch
- Viral Glycoproteins Group, The Pirbright Institute, Ash Rd, Guildford, Surrey GU24 0NF, UK
| | - Dalan Bailey
- Viral Glycoproteins Group, The Pirbright Institute, Ash Rd, Guildford, Surrey GU24 0NF, UK.
- Institute of Immunology and Immunotherapy, The University of Birmingham, Birmingham B15 2TT, UK.
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Mechanism of Tetherin Inhibition of Alphavirus Release. J Virol 2019; 93:JVI.02165-18. [PMID: 30674629 DOI: 10.1128/jvi.02165-18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 01/18/2019] [Indexed: 12/14/2022] Open
Abstract
Tetherin is an interferon-inducible, antiviral host factor that broadly restricts enveloped virus release by tethering budded viral particles to the plasma membrane. In response, many viruses have evolved tetherin antagonists. The human tetherin gene can express two isoforms, long and short, due to alternative translation initiation sites in the N-terminal cytoplasmic tail. The long isoform (L-tetherin) contains 12 extra amino acids in its N terminus, including a dual tyrosine motif (YDYCRV) that is an internalization signal for clathrin-mediated endocytosis and a determinant of NF-κB activation. Tetherin restricts alphaviruses, which are highly organized enveloped RNA viruses that bud from the plasma membrane. L-tetherin is more efficient than S-tetherin in inhibiting alphavirus release in 293 cells. Here, we demonstrated that alphaviruses do not encode an antagonist for either of the tetherin isoforms. Instead, the isoform specificity reflected a requirement for tetherin endocytosis. The YXY motif in L-tetherin was necessary for alphavirus restriction in 293 cells but was not required for rhabdovirus restriction. L-tetherin's inhibition of alphavirus release correlated with its internalization but did not involve NF-κB activation. In contrast, in U-2 OS cells, the YXY motif and the L-tetherin N-terminal domain were not required for either robust tetherin internalization or alphavirus inhibition. Tetherin forms that were negative for restriction accumulated at the surface of infected cells, while the levels of tetherin forms that restrict were decreased. Together, our results suggest that tetherin-mediated virus internalization plays an important role in the restriction of alphavirus release and that cell-type-specific cofactors may promote tetherin endocytosis.IMPORTANCE The mechanisms of tetherin's antiviral activities and viral tetherin antagonism have been studied in detail for a number of different viruses. Although viral countermeasures against tetherin can differ significantly, overall, tetherin's antiviral activity correlates with physical tethering of virus particles to prevent their release. While tetherin can mediate virus endocytic uptake and clearance, this has not been observed to be required for restriction. Here we show that efficient tetherin inhibition of alphavirus release requires efficient tetherin endocytosis. Our data suggest that this endocytic uptake can be mediated by tetherin itself or by a tetherin cofactor that promotes uptake of an endocytosis-deficient variant of tetherin.
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Colomer-Lluch M, Ruiz A, Moris A, Prado JG. Restriction Factors: From Intrinsic Viral Restriction to Shaping Cellular Immunity Against HIV-1. Front Immunol 2018; 9:2876. [PMID: 30574147 PMCID: PMC6291751 DOI: 10.3389/fimmu.2018.02876] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 11/22/2018] [Indexed: 01/20/2023] Open
Abstract
Antiviral restriction factors are host cellular proteins that constitute a first line of defense blocking viral replication and propagation. In addition to interfering at critical steps of the viral replication cycle, some restriction factors also act as innate sensors triggering innate responses against infections. Accumulating evidence suggests an additional role for restriction factors in promoting antiviral cellular immunity to combat viruses. Here, we review the recent progress in our understanding on how restriction factors, particularly APOBEC3G, SAMHD1, Tetherin, and TRIM5α have the cell-autonomous potential to induce cellular resistance against HIV-1 while promoting antiviral innate and adaptive immune responses. Also, we provide an overview of how these restriction factors may connect with protein degradation pathways to modulate anti-HIV-1 cellular immune responses, and we summarize the potential of restriction factors-based therapeutics. This review brings a global perspective on the influence of restrictions factors in intrinsic, innate, and also adaptive antiviral immunity opening up novel research avenues for therapeutic strategies in the fields of drug discovery, gene therapy, and vaccines to control viral infections.
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Affiliation(s)
- Marta Colomer-Lluch
- IrsiCaixa AIDS Research Institute, Germans Trias i Pujol Research Institute, Universitat Autonoma de Barcelona, Badalona, Spain
| | - Alba Ruiz
- IrsiCaixa AIDS Research Institute, Germans Trias i Pujol Research Institute, Universitat Autonoma de Barcelona, Badalona, Spain
| | - Arnaud Moris
- Sorbonne Université, INSERM U1135, CNRS ERL 8255, Centre d'Immunologie et des Maladies Infectieuses (CIMI-Paris), Paris, France
| | - Julia G Prado
- IrsiCaixa AIDS Research Institute, Germans Trias i Pujol Research Institute, Universitat Autonoma de Barcelona, Badalona, Spain
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8
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Foster TL, Pickering S, Neil SJD. Inhibiting the Ins and Outs of HIV Replication: Cell-Intrinsic Antiretroviral Restrictions at the Plasma Membrane. Front Immunol 2018; 8:1853. [PMID: 29354117 PMCID: PMC5758531 DOI: 10.3389/fimmu.2017.01853] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/07/2017] [Indexed: 01/01/2023] Open
Abstract
Like all viruses, human immunodeficiency viruses (HIVs) and their primate lentivirus relatives must enter cells in order to replicate and, once produced, new virions need to exit to spread to new targets. These processes require the virus to cross the plasma membrane of the cell twice: once via fusion mediated by the envelope glycoprotein to deliver the viral core into the cytosol; and secondly by ESCRT-mediated scission of budding virions during release. This physical barrier thus presents a perfect location for host antiviral restrictions that target enveloped viruses in general. In this review we will examine the current understanding of innate host antiviral defences that inhibit these essential replicative steps of primate lentiviruses associated with the plasma membrane, the mechanism by which these viruses have adapted to evade such defences, and the role that this virus/host battleground plays in the transmission and pathogenesis of HIV/AIDS.
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Affiliation(s)
- Toshana L Foster
- Department of Infectious Disease, School of Immunology and Microbial Sciences, King's College London, London, United Kingdom
| | - Suzanne Pickering
- Department of Infectious Disease, School of Immunology and Microbial Sciences, King's College London, London, United Kingdom
| | - Stuart J D Neil
- Department of Infectious Disease, School of Immunology and Microbial Sciences, King's College London, London, United Kingdom
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BST-2 Expression Modulates Small CD4-Mimetic Sensitization of HIV-1-Infected Cells to Antibody-Dependent Cellular Cytotoxicity. J Virol 2017; 91:JVI.00219-17. [PMID: 28331088 DOI: 10.1128/jvi.00219-17] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/13/2017] [Indexed: 12/19/2022] Open
Abstract
Antibodies recognizing conserved CD4-induced (CD4i) epitopes on human immunodeficiency virus type 1 (HIV-1) Env and able to mediate antibody-dependent cellular cytotoxicity (ADCC) have been shown to be present in sera from most HIV-1-infected individuals. These antibodies preferentially recognize Env in its CD4-bound conformation. CD4 downregulation by Nef and Vpu dramatically reduces exposure of CD4i HIV-1 Env epitopes and therefore reduce the susceptibility of HIV-1-infected cells to ADCC mediated by HIV-positive (HIV+) sera. Importantly, this mechanism of immune evasion can be circumvented with small-molecule CD4 mimetics (CD4mc) that are able to transition Env into the CD4-bound conformation and sensitize HIV-1-infected cells to ADCC mediated by HIV+ sera. However, HIV-1 developed additional mechanisms to avoid ADCC, including Vpu-mediated BST-2 antagonism, which decreases the overall amount of Env present at the cell surface. Accordingly, BST-2 upregulation in response to alpha interferon (IFN-α) was shown to increase the susceptibility of HIV-1-infected cells to ADCC despite the activity of Vpu. Here we show that BST-2 upregulation by IFN-β and interleukin-27 (IL-27) also increases the surface expression of Env and thus boosts the ability of CD4mc to sensitize HIV-1-infected cells to ADCC by sera from HIV-1-infected individuals.IMPORTANCE HIV-1 evolved sophisticated strategies to conceal Env epitopes from ADCC-mediating antibodies present in HIV+ sera. Vpu-mediated BST-2 downregulation was shown to decrease ADCC responses by limiting the amount of Env present at the cell surface. This effect of Vpu was shown to be attenuated by IFN-α treatment. Here we show that in addition to IFN-α, IFN-β and IL-27 also affect Vpu-mediated BST-2 downregulation and greatly enhance ADCC responses against HIV-1-infected cells in the presence of CD4mc. These findings may inform strategies aimed at HIV prevention and eradication.
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Mack K, Starz K, Sauter D, Langer S, Bibollet-Ruche F, Learn GH, Stürzel CM, Leoz M, Plantier JC, Geyer M, Hahn BH, Kirchhoff F. Efficient Vpu-Mediated Tetherin Antagonism by an HIV-1 Group O Strain. J Virol 2017; 91:e02177-16. [PMID: 28077643 PMCID: PMC5331793 DOI: 10.1128/jvi.02177-16] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 12/22/2016] [Indexed: 11/20/2022] Open
Abstract
Simian immunodeficiency viruses (SIVs) use their Nef proteins to counteract the restriction factor tetherin. However, a deletion in human tetherin prevents antagonism by the Nef proteins of SIVcpz and SIVgor, which represent the ape precursors of human immunodeficiency virus type 1 (HIV-1). To promote virus release from infected cells, pandemic HIV-1 group M strains evolved Vpu as a tetherin antagonist, while the Nef protein of less widespread HIV-1 group O strains acquired the ability to target a region adjacent to this deletion. In this study, we identified an unusual HIV-1 group O strain (RBF206) that evolved Vpu as an effective antagonist of human tetherin. While both RBF206 Vpu and Nef exert anti-tetherin activity in transient-transfection assays, mainly Vpu promotes RBF206 release in infected CD4+ T cells. Although mutations distinct from the adaptive changes observed in group M Vpus (M-Vpus) were critical for the acquisition of its anti-tetherin activity, RBF206 O-Vpu potently suppresses NF-κB activation and reduces CD4 cell surface expression. Interestingly, RBF206 Vpu counteracts tetherin in a largely species-independent manner, degrading both the long and short isoforms of human tetherin. Downmodulation of CD4, but not counteraction of tetherin, by RBF206 Vpu was dependent on the cellular ubiquitin ligase machinery. Our data present the first example of an HIV-1 group O Vpu that efficiently antagonizes human tetherin and suggest that counteraction by O-Nefs may be suboptimal.IMPORTANCE Previous studies showed that HIV-1 groups M and O evolved two alternative strategies to counteract the human ortholog of the restriction factor tetherin. While HIV-1 group M switched from Nef to Vpu due to a deletion in the cytoplasmic domain of human tetherin, HIV-1 group O, which lacks Vpu-mediated anti-tetherin activity, acquired a Nef protein that is able to target a region adjacent to the deletion. Here we report an unusual exception, identifying a strain of HIV-1 group O (RBF206) whose Vpu protein evolved an effective antagonism of human tetherin. Interestingly, the adaptive changes in RBF206 Vpu are distinct from those found in M-Vpus and mediate efficient counteraction of both the long and short isoforms of this restriction factor. Our results further illustrate the enormous flexibility of HIV-1 in counteracting human defense mechanisms.
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Affiliation(s)
- Katharina Mack
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Kathrin Starz
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Daniel Sauter
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Simon Langer
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | | | - Gerald H Learn
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Christina M Stürzel
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Marie Leoz
- Laboratoire de Virologie, CHU Charles Nicolle, Rouen, France
- EA 2656 GRAM Université de Rouen, Rouen, France
| | - Jean-Christophe Plantier
- Laboratoire de Virologie, CHU Charles Nicolle, Rouen, France
- EA 2656 GRAM Université de Rouen, Rouen, France
- Laboratoire associé au Centre National de Référence du VIH, CHU Charles Nicolle, Rouen, France
| | - Matthias Geyer
- Department of Structural Immunology, Institute of Innate Immunity, University of Bonn, Bonn, Germany
| | - Beatrice H Hahn
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Microbiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
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11
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Lukhele S, Cohen ÉA. Conserved residues within the HIV-1 Vpu transmembrane-proximal hinge region modulate BST2 binding and antagonism. Retrovirology 2017; 14:18. [PMID: 28288652 PMCID: PMC5348903 DOI: 10.1186/s12977-017-0345-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 03/05/2017] [Indexed: 11/10/2022] Open
Abstract
Background BST2 inhibits HIV-1 release by tethering nascent virions to the surface of infected cells. HIV-1 Vpu overcomes this restriction by removing BST2 from viral budding sites via BST2 intracellular trapping and sequestration, surface downregulation and/or displacement mechanisms. Vpu is composed of a short luminal tail, a transmembrane domain (TMD) and a cytoplasmic hinge region that is followed by two helices. BST2 counteraction relies on the ability of Vpu to physically bind BST2 through TMD interactions and recruit the clathrin-dependent trafficking machinery via a canonical acidic di-leucine signalling motif within the helix-2 of Vpu. The highly conserved Vpu transmembrane-proximal hinge region encompasses residues that resemble an acidic leucine-based trafficking motif, whose functional roles are currently ill-defined. In this study, we investigated the contribution of these residues towards Vpu-mediated BST2 antagonism. Results We show that while these conserved residues have no intrinsic activity on the cellular distribution of Vpu in the absence of BST2, they regulate the ability of Vpu to bind to BST2 and, consequently, govern both BST2-dependent trafficking properties of the protein as well as its co-localization with BST2. Moreover, these residues, particularly a glutamic acid residue positioned immediately following the TMD, are a determinant not only for efficient targeting of BST2, but also binding and degradation of CD4, another host membrane protein targeted by Vpu. Mechanistically, our data are consistent with a role of these residues in the maintenance of the Vpu TMD conformational configuration such that interactions with membrane-associated host targets are favoured. Conclusions Altogether, this work demonstrates an important regulatory role of the transmembrane-proximal Vpu hinge region residues towards enabling the protein to efficiently engage its target host proteins. Thus, this highly conserved, cytosolic Vpu hinge region may represent an attractive target for the development of anti-Vpu inhibitors. Electronic supplementary material The online version of this article (doi:10.1186/s12977-017-0345-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sabelo Lukhele
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal (IRCM), 110, Pine Avenue West, Montreal, QC, H2W 1R7, Canada.,Division of Experimental Medicine, McGill University, Montreal, QC, H3A 1A3, Canada
| | - Éric A Cohen
- Laboratory of Human Retrovirology, Institut de Recherches Cliniques de Montréal (IRCM), 110, Pine Avenue West, Montreal, QC, H2W 1R7, Canada. .,Division of Experimental Medicine, McGill University, Montreal, QC, H3A 1A3, Canada. .,Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, QC, H3T 1J4, Canada.
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12
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Arias JF, Colomer-Lluch M, von Bredow B, Greene JM, MacDonald J, O'Connor DH, Serra-Moreno R, Evans DT. Tetherin Antagonism by HIV-1 Group M Nef Proteins. J Virol 2016; 90:10701-10714. [PMID: 27654287 PMCID: PMC5110183 DOI: 10.1128/jvi.01465-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 09/12/2016] [Indexed: 12/20/2022] Open
Abstract
Although Nef is the viral gene product used by most simian immunodeficiency viruses to overcome restriction by tetherin, this activity was acquired by the Vpu protein of HIV-1 group M due to the absence of sequences in human tetherin that confer susceptibility to Nef. Thus, it is widely accepted that HIV-1 group M uses Vpu instead of Nef to counteract tetherin. Challenging this paradigm, we identified Nef alleles of HIV-1 group M isolates with significant activity against human tetherin. These Nef proteins promoted virus release and tetherin downmodulation from the cell surface and, in the context of vpu-deleted HIV-1 recombinants, enhanced virus replication and resistance to antibody-dependent cell-mediated cytotoxicity (ADCC). Further analysis revealed that the Vpu proteins from several of these viruses lack antitetherin activity, suggesting that under certain circumstances, HIV-1 group M Nef may acquire the ability to counteract tetherin to compensate for the loss of this function by Vpu. These observations illustrate the remarkable plasticity of HIV-1 in overcoming restriction by tetherin and challenge the prevailing view that all HIV-1 group M isolates use Vpu to counteract tetherin. IMPORTANCE Most viruses of HIV-1 group M, the main group of HIV-1 responsible for the global AIDS pandemic, use their Vpu proteins to overcome restriction by tetherin (BST-2 or CD317), which is a transmembrane protein that inhibits virus release from infected cells. Here we show that the Nef proteins of certain HIV-1 group M isolates can acquire the ability to counteract tetherin. These results challenge the current paradigm that HIV-1 group M exclusively uses Vpu to counteract tetherin and underscore the importance of tetherin antagonism for efficient viral replication.
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Affiliation(s)
- Juan F Arias
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Marta Colomer-Lluch
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Lubbock, Texas, USA
| | - Benjamin von Bredow
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | | | - Julie MacDonald
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - David H O'Connor
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Ruth Serra-Moreno
- Department of Biological Sciences, College of Arts and Sciences, Texas Tech University, Lubbock, Texas, USA
| | - David T Evans
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
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13
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Differential Control of BST2 Restriction and Plasmacytoid Dendritic Cell Antiviral Response by Antagonists Encoded by HIV-1 Group M and O Strains. J Virol 2016; 90:10236-10246. [PMID: 27581991 DOI: 10.1128/jvi.01131-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 08/29/2016] [Indexed: 12/15/2022] Open
Abstract
BST2/tetherin is a type I interferon (IFN-I)-stimulated host factor that restricts the release of HIV-1 by entrapping budding virions at the cell surface. This membrane-associated protein can also engage and activate the plasmacytoid dendritic cell (pDC)-specific immunoglobulin-like transcript 7 (ILT7) inhibitory receptor to downregulate the IFN-I response by pDCs. Pandemic HIV-1 group M uses Vpu (M-Vpu) to counteract the two BST2 isoforms (long and short) that are expressed in human cells. M-Vpu efficiently downregulates surface long BST2, while it displaces short BST2 molecules away from viral assembly sites. We recently found that this attribute is used by M-Vpu to activate the BST2/ILT7-dependent negative-feedback pathway and to suppress pDC IFN-I responses during sensing of infected cells. However, whether this property is conserved in endemic HIV-1 group O, which has evolved Nef (O-Nef) to counteract specifically the long BST2 isoform, remains unknown. In the present study, we validated that O-Nefs have the capacity to downregulate surface BST2 and enhance HIV-1 particle release although less efficiently than M-Vpu. In contrast to M-Vpu, O-Nef did not efficiently enhance viral spread in T cell culture or displace short BST2 from viral assembly sites to prevent its occlusion by tethered HIV-1 particles. Consequently, O-Nef impairs the ability of BST2 to activate negative ILT7 signaling to suppress the IFN-I response by pDC-containing peripheral blood mononuclear cells (PBMCs) during sensing of infected cells. These distinctive features of BST2 counteraction by O-Nefs may in part explain the limited spread of HIV-1 group O in the human population. IMPORTANCE The geographical distributions and prevalences of different HIV-1 groups show large variations. Understanding drivers of distinctive viral spread may aid in the development of therapeutic strategies for controlling the spread of HIV-1 pandemic strains. The differential spread of HIV-1 groups appears to be linked to their capacities to antagonize the long and short isoforms of the BST2 restriction factor. We found that the endemic HIV-1 group O-encoded BST2 antagonist Nef is unable to counteract the restriction mediated by short BST2, a condition that impairs its ability to activate ILT7 and suppress pDC antiviral responses. This is in contrast to the pandemic HIV-1 group M-specified BST2 countermeasure Vpu, which displays a diverse array of mechanisms to counteract short and long BST2 isoforms, an attribute that allows the effective control of pDC antiviral responses. These findings may help explain the limited spread of HIV-1 group O as well as the continued predominance of HIV-1 group M throughout the world.
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14
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Crespo H, Bertolotti L, Proffiti M, Cascio P, Cerruti F, Acutis PL, de Andrés D, Reina R, Rosati S. Low proviral small ruminant lentivirus load as biomarker of natural restriction in goats. Vet Microbiol 2016; 192:152-162. [PMID: 27527777 DOI: 10.1016/j.vetmic.2016.07.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 07/05/2016] [Accepted: 07/06/2016] [Indexed: 11/16/2022]
Abstract
Small ruminant lentiviruses (SRLV) globally affect welfare and production of sheep and goats and are mainly controlled through elimination of infected animals, independently of the viral kinetics within the single animal. Control programs are based on highly sensitive serological tests, however the existence of low antibody responders leads to the permanent presence of seronegative infected animals in the flock, thus perpetuating the infection. On the other hand, long-term non-progressors show a detectable antibody response not indicative of a shedding animal, suggesting immune contention of infection. In this study, we analyse two goat populations within the same herd, harbouring low or high proviral SRLV loads respectively, both showing a robust antibody response. In vivo findings were confirmed in vitro since fibroblastic cell lines obtained from one high and one low proviral load representative goats, showed respectively a high and a faint production of virus upon infection with reference and field circulating SRLV strains. Differences in virus production were relieved when strain CAEV-Co was used for experimental infection. We analysed LTR promoter activity, proviral load, entry step and production of virus and viral proteins. Intriguingly, proteasomal activity was higher in fibroblasts from low proviral load animals and proteasome inhibition increased viral production in both cell lines, suggesting the implication of active proteasome-dependent restriction factors. Among them, we analysed relative expression and sequences of TRIM5α, APOBEC3 (Z1, Z2, Z3 and Z2-Z3) and BST-2 (Tetherin) and found a global antiviral status in low proviral carriers that may confer protection against viral shedding and disease onset.
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Affiliation(s)
- Helena Crespo
- Instituto de Agrobiotecnología, UPNA-CSIC-Gob, de Navarra, Avda. Pamplona 123, 31192 Mutilva, Spain
| | - Luigi Bertolotti
- Dipartimento di Scienze Veterinarie, Università degli Studi di Torino, L.go P. Braccini 2, 10095 Grugliasco (TO), Italy
| | - Margherita Proffiti
- Dipartimento di Scienze Veterinarie, Università degli Studi di Torino, L.go P. Braccini 2, 10095 Grugliasco (TO), Italy
| | - Paolo Cascio
- Dipartimento di Scienze Veterinarie, Università degli Studi di Torino, L.go P. Braccini 2, 10095 Grugliasco (TO), Italy
| | - Fulvia Cerruti
- Dipartimento di Scienze Veterinarie, Università degli Studi di Torino, L.go P. Braccini 2, 10095 Grugliasco (TO), Italy
| | - Pier Luigi Acutis
- Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Torino, Italy
| | - Damián de Andrés
- Instituto de Agrobiotecnología, UPNA-CSIC-Gob, de Navarra, Avda. Pamplona 123, 31192 Mutilva, Spain
| | - Ramsés Reina
- Instituto de Agrobiotecnología, UPNA-CSIC-Gob, de Navarra, Avda. Pamplona 123, 31192 Mutilva, Spain.
| | - Sergio Rosati
- Dipartimento di Scienze Veterinarie, Università degli Studi di Torino, L.go P. Braccini 2, 10095 Grugliasco (TO), Italy
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15
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Remodeling of the Host Cell Plasma Membrane by HIV-1 Nef and Vpu: A Strategy to Ensure Viral Fitness and Persistence. Viruses 2016; 8:67. [PMID: 26950141 PMCID: PMC4810257 DOI: 10.3390/v8030067] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2016] [Revised: 02/09/2016] [Accepted: 02/16/2016] [Indexed: 02/07/2023] Open
Abstract
The plasma membrane protects the cell from its surroundings and regulates cellular communication, homing, and metabolism. Not surprisingly, the composition of this membrane is highly controlled through the vesicular trafficking of proteins to and from the cell surface. As intracellular pathogens, most viruses exploit the host plasma membrane to promote viral replication while avoiding immune detection. This is particularly true for the enveloped human immunodeficiency virus (HIV), which assembles and obtains its lipid shell directly at the plasma membrane. HIV-1 encodes two proteins, negative factor (Nef) and viral protein U (Vpu), which function primarily by altering the quantity and localization of cell surface molecules to increase virus fitness despite host antiviral immune responses. These proteins are expressed at different stages in the HIV-1 life cycle and employ a variety of mechanisms to target both unique and redundant surface proteins, including the viral receptor CD4, host restriction factors, immunoreceptors, homing molecules, tetraspanins and membrane transporters. In this review, we discuss recent progress in the study of the Nef and Vpu targeting of host membrane proteins with an emphasis on how remodeling of the cell membrane allows HIV-1 to avoid host antiviral immune responses leading to the establishment of systemic and persistent infection.
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16
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Serine Phosphorylation of HIV-1 Vpu and Its Binding to Tetherin Regulates Interaction with Clathrin Adaptors. PLoS Pathog 2015; 11:e1005141. [PMID: 26317613 PMCID: PMC4552633 DOI: 10.1371/journal.ppat.1005141] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 08/11/2015] [Indexed: 02/07/2023] Open
Abstract
HIV-1 Vpu prevents incorporation of tetherin (BST2/ CD317) into budding virions and targets it for ESCRT-dependent endosomal degradation via a clathrin-dependent process. This requires a variant acidic dileucine-sorting motif (ExxxLV) in Vpu. Structural studies demonstrate that recombinant Vpu/tetherin fusions can form a ternary complex with the clathrin adaptor AP-1. However, open questions still exist about Vpu’s mechanism of action. Particularly, whether endosomal degradation and the recruitment of the E3 ubiquitin ligase SCFβTRCP1/2 to a conserved phosphorylated binding site, DSGNES, are required for antagonism. Re-evaluation of the phenotype of Vpu phosphorylation mutants and naturally occurring allelic variants reveals that the requirement for the Vpu phosphoserine motif in tetherin antagonism is dissociable from SCFβTRCP1/2 and ESCRT-dependent tetherin degradation. Vpu phospho-mutants phenocopy ExxxLV mutants, and can be rescued by direct clathrin interaction in the absence of SCFβTRCP1/2 recruitment. Moreover, we demonstrate physical interaction between Vpu and AP-1 or AP-2 in cells. This requires Vpu/tetherin transmembrane domain interactions as well as the ExxxLV motif. Importantly, it also requires the Vpu phosphoserine motif and adjacent acidic residues. Taken together these data explain the discordance between the role of SCFβTRCP1/2 and Vpu phosphorylation in tetherin antagonism, and indicate that phosphorylation of Vpu in Vpu/tetherin complexes regulates promiscuous recruitment of adaptors, implicating clathrin-dependent sorting as an essential first step in tetherin antagonism. Counteraction of tetherin, a host antiviral protein that blocks viral release from infected cells, is an essential attribute of HIV-1 and its related viruses. The HIV-1 accessory protein Vpu binds to tetherin, preventing its incorporation into viral particles, and targets it for ubiquitin-dependent degradation. This involves mis-trafficking of tetherin by a Vpu-dependent mechanism through the engagement of clathrin adaptor proteins. Although structural evidence exists for Vpu and tetherin interacting with clathrin adaptor 1 (AP-1), evidence that it is required for Vpu-mediated tetherin counteraction is still lacking. Tetherin degradation by Vpu also requires an E3 ubiquitin ligase, SCFβTRCP1/2 that binds to phosphorylated serine residues in the Vpu cytoplasmic tail. Again, discrepancies exist about the importance of this interaction in tetherin’s counteraction. Here we show that Vpu phosphorylation, in combination with its physical interaction with tetherin, regulates interaction with both AP-1 and the other major cellular clathrin adaptor, AP-2. These interactions can be decoupled from SCFβTRCP1/2 recruitment, thus indicating clathrin-dependent mis-trafficking as a critical step in tetherin antagonism by Vpu. Additionally, the ability to interact both with AP-1 and AP-2 in a tetherin-dependent manner indicates a redundancy in host cofactors used by Vpu that explains disparate previous observations of its mechanism of action.
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17
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Bego MG, Côté É, Aschman N, Mercier J, Weissenhorn W, Cohen ÉA. Vpu Exploits the Cross-Talk between BST2 and the ILT7 Receptor to Suppress Anti-HIV-1 Responses by Plasmacytoid Dendritic Cells. PLoS Pathog 2015; 11:e1005024. [PMID: 26172439 PMCID: PMC4501562 DOI: 10.1371/journal.ppat.1005024] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 06/16/2015] [Indexed: 11/25/2022] Open
Abstract
Plasmacytoid dendritic cells (pDCs) constitute a major source of type-I interferon (IFN-I) production during acute HIV infection. Their activation results primarily from TLR7-mediated sensing of HIV-infected cells. However, the interactions between HIV-infected T cells and pDCs that modulate this sensing process remain poorly understood. BST2/Tetherin is a restriction factor that inhibits HIV release by cross-linking virions onto infected cell surface. BST2 was also shown to engage the ILT7 pDC-specific inhibitory receptor and repress TLR7/9-mediated IFN-I production by activated pDCs. Here, we show that Vpu, the HIV-1 antagonist of BST2, suppresses TLR7-mediated IFN-I production by pDC through a mechanism that relies on the interaction of BST2 on HIV-producing cells with ILT7. Even though Vpu downregulates surface BST2 as a mean to counteract the restriction on HIV-1 release, we also find that the viral protein re-locates remaining BST2 molecules outside viral assembly sites where they are free to bind and activate ILT7 upon cell-to-cell contact. This study shows that through a targeted regulation of surface BST2, Vpu promotes HIV-1 release and limits pDC antiviral responses upon sensing of infected cells. This mechanism of innate immune evasion is likely to be important for an efficient early viral dissemination during acute infection. Plasmacytoid dendritic cells (pDCs) produce large quantities of type I interferon (IFN-I) upon stimulation by many viruses, including HIV. Their activation is very effective following cell contacts with HIV-1-infected CD4+ T cells. We investigated whether HIV-1 could regulate the antiviral responses of pDCs triggered upon sensing of infected cells. We show that HIV-1 suppresses the levels of IFN-I produced by pDCs through a process that requires expression of the Vpu accessory protein in virus-producing cells. A well-described role of Vpu is to promote efficient HIV-1 production by counteracting BST2, a host factor that entraps nascent viral particle at the cell surface. Apart from its antiviral activity, BST2 was reported to inhibit IFN-I production by pDCs through binding and activation of the ILT7 pDC-specific inhibitory receptor. Our results reveal that through a highly sophisticated targeted regulation of BST2 levels at the surface of infected cells, Vpu promotes HIV-1 release and limits IFN-I production by pDCs via the negative signaling exerted by the BST2-ILT7 pair. Overall, this study sheds light on a novel Vpu-BST2 interaction that allows HIV-1 to escape pDC antiviral responses. This modulation of pDC antiviral response by HIV Vpu may facilitate the initial viral expansion during acute infection.
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Affiliation(s)
- Mariana G. Bego
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
| | - Édouard Côté
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
| | - Nick Aschman
- Université Grenoble Alpes, Unit of Virus Host Cell Interactions (UVHCI), CNRS, UVHCI, Grenoble, France
| | - Johanne Mercier
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
| | - Winfried Weissenhorn
- Université Grenoble Alpes, Unit of Virus Host Cell Interactions (UVHCI), CNRS, UVHCI, Grenoble, France
| | - Éric A. Cohen
- Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, Quebec, Canada
- * E-mail:
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18
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Galão RP, Pickering S, Curnock R, Neil SJD. Retroviral retention activates a Syk-dependent HemITAM in human tetherin. Cell Host Microbe 2015; 16:291-303. [PMID: 25211072 PMCID: PMC4161388 DOI: 10.1016/j.chom.2014.08.005] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 07/18/2014] [Accepted: 08/07/2014] [Indexed: 12/27/2022]
Abstract
Tetherin (BST2/CD317) restricts the release of enveloped viral particles from infected cells. Coupled to this virion retention, hominid tetherins induce proinflammatory gene expression via activating NF-κB. We investigated the events initiating this tetherin-induced signaling and show that physical retention of retroviral particles induces the phosphorylation of conserved tyrosine residues in the cytoplasmic tails of tetherin dimers. This phosphorylation induces the recruitment of spleen tyrosine kinase (Syk), which is required for downstream NF-κB activation, indicating that the tetherin cytoplasmic tail resembles the hemi-immunoreceptor tyrosine-based activation motifs (hemITAMs) found in C-type lectin pattern recognition receptors. Retroviral-induced tetherin signaling is coupled to the cortical actin cytoskeleton via the Rac-GAP-containing protein RICH2 (ARHGAP44), and a naturally occurring tetherin polymorphism with reduced RICH2 binding exhibits decreased phosphorylation and NF-κB activation. Thus, upon virion retention, this linkage to the actin cytoskeleton likely triggers tetherin phosphorylation and subsequent signal transduction to induce an antiviral state. A hemITAM in human tetherin is phosphorylated upon viral restriction Tetherin phosphorylation recruits and is dependent upon the kinase Syk The RICH2-tetherin interaction couples tetherin signaling to the actin cytoskeleton A human polymorphism in tetherin abolishes RICH2 interactions and signal transduction
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Affiliation(s)
- Rui Pedro Galão
- Department of Infectious Disease, King's College London School of Medicine, Guy's Hospital, London SE1 9RT, UK
| | - Suzanne Pickering
- Department of Infectious Disease, King's College London School of Medicine, Guy's Hospital, London SE1 9RT, UK
| | - Rachel Curnock
- School of Biochemistry, Faculty of Medical and Veterinary Sciences, University of Bristol, Bristol BS8 1TD, UK
| | - Stuart J D Neil
- Department of Infectious Disease, King's College London School of Medicine, Guy's Hospital, London SE1 9RT, UK.
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The sheep tetherin paralog oBST2B blocks envelope glycoprotein incorporation into nascent retroviral virions. J Virol 2014; 89:535-44. [PMID: 25339764 DOI: 10.1128/jvi.02751-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
UNLABELLED Bone marrow stromal cell antigen 2 (BST2) is a cellular restriction factor with a broad antiviral activity. In sheep, the BST2 gene is duplicated into two paralogs termed oBST2A and oBST2B. oBST2A impedes viral exit of the Jaagsiekte sheep retroviruses (JSRV), most probably by retaining virions at the cell membrane, similar to the "tethering" mechanism exerted by human BST2. In this study, we provide evidence that unlike oBST2A, oBST2B is limited to the Golgi apparatus and disrupts JSRV envelope (Env) trafficking by sequestering it. In turn, oBST2B leads to a reduction in Env incorporation into viral particles, which ultimately results in the release of virions that are less infectious. Furthermore, the activity of oBST2B does not seem to be restricted to retroviruses, as it also acts on vesicular stomatitis virus glycoproteins. Therefore, we suggest that oBST2B exerts antiviral activity using a mechanism distinct from the classical tethering restriction observed for oBST2A. IMPORTANCE BST2 is a powerful cellular restriction factor against a wide range of enveloped viruses. Sheep possess two paralogs of the BST2 gene called oBST2A and oBST2B. JSRV, the causative agent of a transmissible lung cancer of sheep, is known to be restricted by oBST2A. In this study, we show that unlike oBST2A, oBST2B impairs the normal cellular trafficking of JSRV envelope glycoproteins by sequestering them within the Golgi apparatus. We also show that oBST2B decreases the incorporation of envelope glycoprotein into JSRV viral particles, which in turn reduces virion infectivity. In conclusion, oBST2B exerts a novel antiviral activity that is distinct from those of BST2 proteins of other species.
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20
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Yin X, Guo M, Gu Q, Wu X, Wei P, Wang X. Antiviral potency and functional analysis of tetherin orthologues encoded by horse and donkey. Virol J 2014; 11:151. [PMID: 25158826 PMCID: PMC4152588 DOI: 10.1186/1743-422x-11-151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 08/22/2014] [Indexed: 12/11/2022] Open
Abstract
Background Tetherin is an interferon-inducible host cell factor that blocks the viral particle release of the enveloped viruses. Most knowledge regarding the interaction between tetherin and viruses has been obtained using the primate lentiviral system. However, much less is known about the functional roles of tetherin on other lentiviruses. Equine infectious anemia virus (EIAV) is an important macrophage-tropic lentivirus that has been widely used as a practical model for investigating the evolution of the host-virus relationship. The host range of EIAV is reported to include all members of the Equidae family. However, EIAV has different clinical responses in horse and donkey. It’s intriguing to investigate the similarities and differences between the tetherin orthologues encoded by horse and donkey. Results We report here that there are two equine tetherin orthologues. Compared to horse tetherin, there are three valine amino acid deletions within the transmembrane domain and three distinct mutations within the ectodomain of donkey tetherin. However, the antiviral activity of donkey tetherin was not affected by amino acid deletion or substitution. In addition, both tetherin orthologues encoded by horse and donkey are similarly sensitive to EIAV Env protein, and equally activate NF-κB signaling. Conclusion Our data suggest that both tetherin orthologues encoded by horse and donkey showed similar antiviral activities and abilities to induce NF-κB signaling. In addition, the phenomenon about the differential responses of horses and donkeys to infection with EIAV was not related with the differences in the structure of the corresponding tetherin orthologues.
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Affiliation(s)
| | | | | | | | - Ping Wei
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China.
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