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Wilk AJ, Marceau JO, Kazer SW, Fleming I, Miao VN, Galvez-Reyes J, Kimata JT, Shalek AK, Holmes S, Overbaugh J, Blish CA. Pro-inflammatory feedback loops define immune responses to pathogenic Lentivirus infection. Genome Med 2024; 16:24. [PMID: 38317183 PMCID: PMC10840164 DOI: 10.1186/s13073-024-01290-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 01/19/2024] [Indexed: 02/07/2024] Open
Abstract
BACKGROUND The Lentivirus human immunodeficiency virus (HIV) causes chronic inflammation and AIDS in humans, with variable rates of disease progression between individuals driven by both host and viral factors. Similarly, simian lentiviruses vary in their pathogenicity based on characteristics of both the host species and the virus strain, yet the immune underpinnings that drive differential Lentivirus pathogenicity remain incompletely understood. METHODS We profile immune responses in a unique model of differential lentiviral pathogenicity where pig-tailed macaques are infected with highly genetically similar variants of SIV that differ in virulence. We apply longitudinal single-cell transcriptomics to this cohort, along with single-cell resolution cell-cell communication techniques, to understand the immune mechanisms underlying lentiviral pathogenicity. RESULTS Compared to a minimally pathogenic lentiviral variant, infection with a highly pathogenic variant results in a more delayed, broad, and sustained activation of inflammatory pathways, including an extensive global interferon signature. Conversely, individual cells infected with highly pathogenic Lentivirus upregulated fewer interferon-stimulated genes at a lower magnitude, indicating that highly pathogenic Lentivirus has evolved to partially escape from interferon responses. Further, we identify CXCL10 and CXCL16 as important molecular drivers of inflammatory pathways specifically in response to highly pathogenic Lentivirus infection. Immune responses to highly pathogenic Lentivirus infection are characterized by amplifying regulatory circuits of pro-inflammatory cytokines with dense longitudinal connectivity. CONCLUSIONS Our work presents a model of lentiviral pathogenicity where failures in early viral control mechanisms lead to delayed, sustained, and amplifying pro-inflammatory circuits, which in turn drives disease progression.
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Affiliation(s)
- Aaron J Wilk
- Stanford Immunology Program, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Medical Scientist Training Program, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Joshua O Marceau
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Samuel W Kazer
- Institute for Medical Engineering & Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, 02139, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Ira Fleming
- Institute for Medical Engineering & Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, 02139, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Vincent N Miao
- Institute for Medical Engineering & Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, 02139, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
- Program in Health Sciences & Technology, Harvard Medical School & MIT, Boston, MA, 02115, USA
| | - Jennyfer Galvez-Reyes
- Institute for Medical Engineering & Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, 02139, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Jason T Kimata
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Alex K Shalek
- Institute for Medical Engineering & Science, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Ragon Institute of MGH, MIT, and Harvard, Cambridge, MA, 02139, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Susan Holmes
- Department of Statistics, Stanford University, Stanford, CA, 94305, USA
| | - Julie Overbaugh
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA
| | - Catherine A Blish
- Stanford Immunology Program, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Medical Scientist Training Program, Stanford University School of Medicine, Stanford, CA, 94305, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA.
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Lungu C, Overmars RJ, Grundeken E, Boers PHM, van der Ende ME, Mesplède T, Gruters RA. Genotypic and Phenotypic Characterization of Replication-Competent HIV-2 Isolated from Controllers and Progressors. Viruses 2023; 15:2236. [PMID: 38005913 PMCID: PMC10675771 DOI: 10.3390/v15112236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 11/03/2023] [Accepted: 11/07/2023] [Indexed: 11/26/2023] Open
Abstract
Although some individuals with HIV-2 develop severe immunodeficiency and AIDS-related complications, most may never progress to AIDS. Replication-competent HIV-2 isolated from asymptomatic long-term non-progressors (controllers) have lower replication rates than viruses from individuals who progress to AIDS (progressors). To investigate potential retroviral factors that correlate with disease progression in HIV-2, we sequenced the near full-length genomes of replication-competent viruses previously outgrown from controllers and progressors and used phylogeny to seek genotypic correlates of disease progression. We validated the integrity of all open reading frames and used cell-based assays to study the retroviral transcriptional activity of the long terminal repeats (LTRs) and Tat proteins of HIV-2 from controllers and progressors. Overall, we did not identify genotypic defects that may contribute to HIV-2 non-progression. Tat-induced, LTR-mediated transcription was comparable between viruses from controllers and progressors. Our results were obtained from a small number of participants and should be interpreted accordingly. Overall, they suggest that progression may be determined before or during integration of HIV-2.
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Affiliation(s)
- Cynthia Lungu
- Viroscience Department, Erasmus Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands; (C.L.); (R.J.O.); (E.G.); (P.H.M.B.)
| | - Ronald J. Overmars
- Viroscience Department, Erasmus Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands; (C.L.); (R.J.O.); (E.G.); (P.H.M.B.)
| | - Esmée Grundeken
- Viroscience Department, Erasmus Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands; (C.L.); (R.J.O.); (E.G.); (P.H.M.B.)
| | - Patrick H. M. Boers
- Viroscience Department, Erasmus Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands; (C.L.); (R.J.O.); (E.G.); (P.H.M.B.)
| | - Marchina E. van der Ende
- Department of Internal Medicine, Erasmus Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands;
| | - Thibault Mesplède
- Viroscience Department, Erasmus Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands; (C.L.); (R.J.O.); (E.G.); (P.H.M.B.)
| | - Rob A. Gruters
- Viroscience Department, Erasmus Medical Center, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands; (C.L.); (R.J.O.); (E.G.); (P.H.M.B.)
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Geographical distribution of host's specific SARS-CoV-2 mutations in the early phase of the COVID-19 pandemic. Gene 2022; 851:147020. [PMCID: PMC9635256 DOI: 10.1016/j.gene.2022.147020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 10/24/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022]
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Substitutions in Nef That Uncouple Tetherin and SERINC5 Antagonism Impair Simian Immunodeficiency Virus Replication in Primary Rhesus Macaque Lymphocytes. J Virol 2022; 96:e0017622. [PMID: 35536019 DOI: 10.1128/jvi.00176-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Most simian immunodeficiency viruses (SIVs) use Nef to counteract restriction by the tetherin proteins of their nonhuman primate hosts. In addition to counteracting tetherin, SIV Nef has a number of other functions, including the downmodulation of CD3, CD4, and major histocompatibility complex class I (MHC I) molecules from the surface of SIV-infected cells and the enhancement of viral infectivity by preventing the incorporation of SERINC5 into virions. Although these activities require different surfaces of Nef, they can be difficult to separate because of their dependence on similar interactions with AP-1 or AP-2 for clathrin-mediated endocytosis. We previously observed extensive overlap of the SIV Nef residues required for counteracting tetherin and SERINC5. Here, we define substitutions in Nef that separate anti-tetherin activity from SERINC5 antagonism and other activities of Nef. This information was used to engineer an infectious molecular clone of SIV (SIVmac239nefSA) that is sensitive to tetherin but retains CD3, CD4, MHC I, and SERINC5 downmodulation. In primary rhesus macaque CD4+ T cells, SIVmac239nefSA exhibits impaired replication compared to wild-type SIVmac239 under conditions of interferon-induced upregulation of tetherin. These results demonstrate that tetherin antagonism can be separated from other Nef functions and that resistance to tetherin is essential for optimal replication in primary CD4+ T cells. IMPORTANCE Tetherin is an interferon-inducible transmembrane protein that prevents the detachment of enveloped viruses from infected cells by physically tethering nascent virions to cellular membranes. SIV Nef downmodulates simian tetherin to overcome this restriction in nonhuman primate hosts. Nef also enhances virus infectivity by preventing the incorporation of SERINC5 into virions and contributes to immune evasion by downmodulating other proteins from the cell surface. To assess the contribution of tetherin antagonism to virus replication, we engineered an infectious molecular clone of SIV with substitutions in Nef that uncouple tetherin antagonism from other Nef functions. These substitutions impaired virus replication in interferon-treated macaque CD4+ T cells, revealing the impact of tetherin on SIV replication under physiological conditions in primary CD4+ lymphocytes.
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Selective Disruption of SERINC5 Antagonism by Nef Impairs SIV Replication in Primary CD4 + T Cells. J Virol 2021; 95:JVI.01911-20. [PMID: 33504599 PMCID: PMC8103682 DOI: 10.1128/jvi.01911-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Nef proteins of HIV-1 and SIV enhance viral infectivity by preventing the incorporation of the multipass transmembrane protein serine incorporator 5 (SERINC5), and to a lesser extent SERINC3, into virions. In addition to counteracting SERINCs, SIV Nef also downmodulates several transmembrane proteins from the surface of virus-infected cells, including simian tetherin, CD4 and MHC class I (MHC I) molecules. From a systematic analysis of alanine substitutions throughout the SIVmac239 Nef protein, we identified residues that are required to counteract SERINC5. This information was used to engineer an infectious molecular clone of SIV (SIVmac239nef AV), which differs by two amino acids in the N-terminal domain of Nef that make the virus sensitive to SERINC5 while retaining other activities of Nef. SIVmac239nef AV downmodulates CD3, CD4, MHC I and simian tetherin, but cannot counteract SERINC5. In primary rhesus macaque CD4+ T cells, SIVmac239nef AV exhibits impaired infectivity and replication compared to wild-type SIVmac239. These results demonstrate that SERINC5 antagonism can be separated from other Nef functions and reveal the impact of SERINC5 on lentiviral replication.Importance: SERINC5, a multipass transmembrane protein, is incorporated into retroviral particles during assembly. This leads to a reduction of particle infectivity by inhibiting virus fusion with the target cell membrane. The Nef proteins of HIV-1 and SIV enhance viral infectivity by preventing the incorporation of SERINC5 into virions. However, the relevance of this restriction factor in viral replication has not been elucidated. Here we report a systematic mapping of Nef residues required for SERINC5 antagonism. Counter screens for three other functions of Nef helped identify two residues in the N-terminal domain of Nef, which when mutated make Nef selectively susceptible to SERINC5. Since Nef is multi-functional, genetic separation of SERINC5 antagonism from its other functions affords comparison of the replication of isogenic viruses that are or are not sensitive to SERINC5. Such a strategy revealed the impact of SERINC5 on SIV replication in primary rhesus macaque CD4+ T-cells.
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Joas S, Sauermann U, Roshani B, Klippert A, Daskalaki M, Mätz-Rensing K, Stolte-Leeb N, Heigele A, Tharp GK, Gupta PM, Nelson S, Bosinger S, Parodi L, Giavedoni L, Silvestri G, Sauter D, Stahl-Hennig C, Kirchhoff F. Nef-Mediated CD3-TCR Downmodulation Dampens Acute Inflammation and Promotes SIV Immune Evasion. Cell Rep 2021; 30:2261-2274.e7. [PMID: 32075764 PMCID: PMC7052273 DOI: 10.1016/j.celrep.2020.01.069] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 12/10/2019] [Accepted: 01/21/2020] [Indexed: 01/05/2023] Open
Abstract
The inability of Nef to downmodulate the CD3-T cell receptor (TCR) complex distinguishes HIV-1 from other primate lentiviruses and may contribute to its high virulence. However, the role of this Nef function in virus-mediated immune activation and pathogenicity remains speculative. Here, we selectively disrupted this Nef activity in SIVmac239 and analyzed the consequences for the virological, immunological, and clinical outcome of infection in rhesus macaques. The inability to downmodulate CD3-TCR does not impair viral replication during acute infection but is associated with increased immune activation and antiviral gene expression. Subsequent early reversion in three of six animals suggests strong selective pressure for this Nef function and is associated with high viral loads and progression to simian AIDS. In the absence of reversions, however, viral replication and the clinical course of infection are attenuated. Thus, Nef-mediated downmodulation of CD3 dampens the inflammatory response to simian immunodeficiency virus (SIV) infection and seems critical for efficient viral immune evasion. HIV-1 lacks the CD3 downmodulation function of Nef that is otherwise conserved in primate lentiviruses. Joas et al. disrupted this Nef activity in SIVmac239 and show that Nef-mediated downmodulation of CD3 dampens inflammatory responses to SIV. This promotes effective immune evasion and maintenance of high viral loads in infected rhesus macaques.
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Affiliation(s)
- Simone Joas
- Institute of Molecular Virology - Ulm University Medical Center, Meyerhofstraße 1, 89081 Ulm, Germany
| | | | - Berit Roshani
- German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
| | | | - Maria Daskalaki
- German Primate Center, Kellnerweg 4, 37077 Göttingen, Germany
| | | | | | - Anke Heigele
- Institute of Molecular Virology - Ulm University Medical Center, Meyerhofstraße 1, 89081 Ulm, Germany
| | - Gregory K Tharp
- Yerkes Primate Research Center, Emory Vaccine Center, and Department of Pathology, Emory University, Atlanta, GA, USA
| | - Prachi Mehrotra Gupta
- Yerkes Primate Research Center, Emory Vaccine Center, and Department of Pathology, Emory University, Atlanta, GA, USA
| | - Sydney Nelson
- Yerkes Primate Research Center, Emory Vaccine Center, and Department of Pathology, Emory University, Atlanta, GA, USA
| | - Steven Bosinger
- Yerkes Primate Research Center, Emory Vaccine Center, and Department of Pathology, Emory University, Atlanta, GA, USA
| | - Laura Parodi
- Host-Pathogen Interactions Program, Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Luis Giavedoni
- Host-Pathogen Interactions Program, Southwest National Primate Research Center, Texas Biomedical Research Institute, San Antonio, TX, USA
| | - Guido Silvestri
- Yerkes Primate Research Center, Emory Vaccine Center, and Department of Pathology, Emory University, Atlanta, GA, USA
| | - Daniel Sauter
- Institute of Molecular Virology - Ulm University Medical Center, Meyerhofstraße 1, 89081 Ulm, Germany
| | | | - Frank Kirchhoff
- Institute of Molecular Virology - Ulm University Medical Center, Meyerhofstraße 1, 89081 Ulm, Germany.
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Schouest B, Leslie GJ, Hoxie JA, Maness NJ. Tetherin downmodulation by SIVmac Nef lost with the H196Q escape variant is restored by an upstream variant. PLoS One 2020; 15:e0225420. [PMID: 32764749 PMCID: PMC7413475 DOI: 10.1371/journal.pone.0225420] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 07/13/2020] [Indexed: 01/17/2023] Open
Abstract
The H196 residue in SIVmac239 Nef is conserved across the majority of HIV and SIV isolates, lies immediately adjacent to the AP-2 (adaptor protein 2) binding di-leucine domain (ExxxLM195), and is critical for several described AP-2 dependent Nef functions, including the downregulation of tetherin (BST-2/CD317), CD4, and others. Surprisingly, many stocks of the closely related SIVmac251 swarm virus harbor a nef allele encoding a Q196. In SIVmac239, this variant is associated with loss of multiple AP-2 dependent functions. Publicly available sequences for SIVmac251 stocks were mined for variants linked to Q196 that might compensate for functional defects associated with this residue. Variants were engineered into the SIVmac239 backbone and in Nef expression plasmids and flow cytometry was used to examine surface tetherin expression in primary CD4 T cells and surface CD4 expression in SupT1 cells engineered to express rhesus CD4. We found that SIVmac251 stocks that encode a Q196 residue in Nef uniformly also encode an upstream R191 residue. We show that R191 restores the ability of Nef to downregulate tetherin in the presence of Q196 and has a similar but less pronounced impact on CD4 expression. However, a published report showed Q196 commonly evolves to H196 in vivo, suggesting a fitness cost. R191 may represent compensatory evolution to restore the ability to downregulate tetherin lost in viruses harboring Q196.
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Affiliation(s)
- Blake Schouest
- Division of Microbiology, Tulane National Primate Research Center, Covington, LA, United States of America
| | - George J. Leslie
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - James A. Hoxie
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Nicholas J. Maness
- Division of Microbiology, Tulane National Primate Research Center, Covington, LA, United States of America
- Department of Microbiology and Immunology, School of Medicine, Tulane University Health Sciences Center, New Orleans, LA, United States of America
- * E-mail:
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Loss of Nef-mediated CD3 down-regulation in the HIV-1 lineage increases viral infectivity and spread. Proc Natl Acad Sci U S A 2020; 117:7382-7391. [PMID: 32179688 PMCID: PMC7132320 DOI: 10.1073/pnas.1921135117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Lentiviruses encode accessory proteins to manipulate their host cells in order to efficiently replicate and evade antiviral defenses. Interestingly, most lentiviral Nefs down-regulate CD3 from the surface of infected T cells to perturb immune responses. However, for reasons that are incompletely understood, HIV-1 and its simian immunodeficiency virus ancestors lack this function. Here, we report that engineering HIV-1 for Nef-mediated down-regulation of CD3 reduces Env-dependent HIV-1 infectivity, resulting in less efficient cell-to-cell spread and replication. Our data suggest that HIV-1 may have evolved to lose the CD3 down-modulation function of Nef in order to allow T cell activation and to boost viral replication, possibly at the cost of less effective immune evasion and increased pathogenicity. Nef is an accessory protein of primate lentiviruses that is essential for efficient replication and pathogenesis of HIV-1. A conserved feature of Nef proteins from different lentiviral lineages is the ability to modulate host protein trafficking and down-regulate a number of cell surface receptors to enhance replication and promote immune evasion. Notably, the inability of Nef to down-regulate CD3 from infected T cells distinguishes HIV-1 Nef and its direct simian precursors from other primate lentiviruses. Why HIV-1 does not employ this potential immune evasion strategy is not fully understood. Using chimeric HIV-1 constructs expressing lentiviral Nef proteins that differ in their ability to down-modulate CD3, we show that retaining CD3 on the surface of infected primary T cells results in increased viral replication and cell-to-cell spread. We identified increased expression of envelope (Env) trimers at the cell surface and increased Env incorporation into virions as the determinants for the Nef- and CD3-dependent enhancement of viral infectivity. Importantly, this was independent of Nef-mediated antagonism of the host restriction factor SERINC5. CD3 retention on the surface of infected primary T cells also correlated with increased T cell signaling, activation, and cell death during cell-to-cell spread. Taken together, our results show that loss of an otherwise conserved function of Nef has a positive effect on HIV-1 replication, allowing for more efficient replication while potentially contributing to HIV-1 pathogenesis by triggering T cell activation and cell death during viral spread.
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Hirao K, Andrews S, Kuroki K, Kusaka H, Tadokoro T, Kita S, Ose T, Rowland-Jones SL, Maenaka K. Structure of HIV-2 Nef Reveals Features Distinct from HIV-1 Involved in Immune Regulation. iScience 2019; 23:100758. [PMID: 31927483 PMCID: PMC6956826 DOI: 10.1016/j.isci.2019.100758] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 11/24/2019] [Accepted: 12/03/2019] [Indexed: 01/07/2023] Open
Abstract
The human immunodeficiency virus (HIV) accessory protein Nef plays a major role in establishing and maintaining infection, particularly through immune evasion. Many HIV-2-infected people experience long-term viral control and survival, resembling HIV-1 elite control. HIV-2 Nef has overlapping but also distinct functions from HIV-1 Nef. Here we report the crystal structure of HIV-2 Nef core. The di-leucine sorting motif forms a helix bound to neighboring molecules, and moreover, isothermal titration calorimetry demonstrated that the CD3 endocytosis motif can directly bind to HIV-2 Nef, ensuring AP-2-mediated endocytosis for CD3. The highly conserved C-terminal region forms a α-helix, absent from HIV-1. We further determined the structure of simian immunodeficiency virus (SIV) Nef harboring this region, demonstrating similar C-terminal α-helix, which may contribute to AP-1 binding for MHC-I downregulation. These results provide insights into the distinct pathogenesis of HIV-2 infection. Structure of HIV-2 Nef revealed a conserved C-terminal α-helix not present in HIV-1 C-terminal structure is conserved in SIV Nef, likely involved in MHC-I downregulation Di-leucine AP-2-mediated sorting motif forms a helix bound to the α1 and α2 helices ITC demonstrated that the CD3 endocytosis motif can directly bind to HIV-2 Nef
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Affiliation(s)
- Kengo Hirao
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Sophie Andrews
- Nuffield Department of Medicine, University of Oxford, NDM Research Building, Oxford OX3 7FZ, UK
| | - Kimiko Kuroki
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Hiroki Kusaka
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Takashi Tadokoro
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Shunsuke Kita
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Toyoyuki Ose
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan; Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Sarah L Rowland-Jones
- Nuffield Department of Medicine, University of Oxford, NDM Research Building, Oxford OX3 7FZ, UK.
| | - Katsumi Maenaka
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
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Abstract
The accessory protein Nef of human immunodeficiency virus (HIV) is a primary determinant of viral pathogenesis. Nef is abundantly expressed during infection and reroutes a variety of cell surface proteins to disrupt host immunity and promote the viral replication cycle. Nef counteracts host defenses by sequestering and/or degrading its targets via the endocytic and secretory pathways. Nef does this by physically engaging a number of host trafficking proteins. Substantial progress has been achieved in identifying the targets of Nef, and a structural and mechanistic understanding of Nef's ability to command the protein trafficking machinery has recently started to coalesce. Comparative analysis of HIV and simian immunodeficiency virus (SIV) Nef proteins in the context of recent structural advances sheds further light on both viral evolution and the mechanisms whereby trafficking is hijacked. This review describes how advances in cell and structural biology are uncovering in growing detail how Nef subverts the host immune system, facilitates virus release, and enhances viral infectivity.
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HIV-2 Depletes CD4 T Cells through Pyroptosis despite Vpx-Dependent Degradation of SAMHD1. J Virol 2019; 93:JVI.00666-19. [PMID: 31578293 DOI: 10.1128/jvi.00666-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 09/11/2019] [Indexed: 02/07/2023] Open
Abstract
Human immunodeficiency virus type 2 (HIV-2) infection results in a milder course of disease and slower progression to AIDS than does HIV-1. We hypothesized that this difference may be due to degradation of the sterile alpha motif and HD domain 1 (SAMHD1) host restriction factor by the HIV-2 Vpx gene product, thereby diminishing abortive infection and pyroptotic cell death within bystander CD4 T cells. We have compared CD4 T cell death in tonsil-derived human lymphoid aggregate cultures (HLACs) infected with wild-type HIV-2, HIV-2 ΔVpx, or HIV-1. In contrast to our hypothesis, HIV-2, HIV-2 ΔVpx, and HIV-1 induced similar levels of bystander CD4 T cell death. In all cases, cell death was blocked by AMD3100, a CXCR4 entry inhibitor, but not by raltegravir, an integrase, indicating that only early life cycle events were required. Cell death was also blocked by a caspase-1 inhibitor, a key enzyme promoting pyroptosis, but not by a caspase-3 inhibitor, an important enzyme in apoptosis. HIV-1-induced abortive infection and pyroptotic cell death were also not reduced by forced encapsidation of HIV-2 Vpx into HIV-1 virions. Together, these findings indicate that HIV-2 and HIV-1 support similar levels of CD4 T cell depletion in vitro despite HIV-2 Vpx-mediated degradation of the SAMHD1 transcription factor. The milder disease course observed with HIV-2 infection likely stems from factors other than abortive infection and caspase-1-dependent pyroptosis in bystander CD4 T cells.IMPORTANCE CD4 T cell depletion during HIV-1 infection involves the demise of bystander CD4 T cells due to abortive infection, viral DNA sensing, inflammasome assembly, and death by caspase-1-dependent pyroptosis. HIV-2 infection is associated with milder disease and lower rates of CD4 T cell loss. We hypothesized that HIV-2 infection produces lower levels of pyroptosis due to the action of its Vpx gene product. Vpx degrades the SAMHD1 restriction factor, potentially reducing abortive forms of infection. However, in tonsil cell cultures, HIV-2, HIV-2 ΔVpx, and HIV-1 induced indistinguishable levels of pyroptosis. Forced encapsidation of Vpx into HIV-1 virions also did not reduce pyroptosis. Thus, SAMHD1 does not appear to play a key role in the induction of bystander cell pyroptosis. Additionally, the milder clinical course of HIV-2-induced disease is apparently not explained by a decrease in this inflammatory form of programmed cell death.
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T-cell and B-cell perturbations identify distinct differences in HIV-2 compared with HIV-1-induced immunodeficiency. AIDS 2019; 33:1131-1141. [PMID: 30845070 DOI: 10.1097/qad.0000000000002184] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND For unknown reasons, HIV-2 is less pathogenic than HIV-1, and HIV-2-induced immunodeficiency may be different from that caused by HIV-1. Previous immunological studies have hinted at possible shifts in both T-cell and B-cell subsets, which we aimed to characterize further. METHODS From an HIV clinic in Guinea-Bissau, 63 HIV-2, 83 HIV-1, and 26 HIV-negative participants were included. All HIV-infected participants were ART-naive. The following cell subsets were analysed by flow cytometry; T cells (maturation and activation), regulatory T cells, and B cells (maturation and activation). RESULTS After standardizing for sex, age, and CD4 T-cell count HIV-2 had 0.938 log10 copies/ml lower HIV RNA levels than the HIV-1-infected patients. Whereas T-cell maturation and regulatory T-cell profiles were similar between patients, HIV-2-infected patients had higher proportions of CD8CD28 and lower proportions of CD8PD-1+ T cells than HIV-1-infected patients. This finding was independent of HIV RNA levels. HIV-2 was also associated with a more preserved proportion of naive B cells. CONCLUSION HIV-2 is characterized by lower viral load, and lower T-cell activation, which may account for the slower disease progression.
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Preadaptation of Simian Immunodeficiency Virus SIVsmm Facilitated Env-Mediated Counteraction of Human Tetherin by Human Immunodeficiency Virus Type 2. J Virol 2018; 92:JVI.00276-18. [PMID: 29976668 DOI: 10.1128/jvi.00276-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 06/23/2018] [Indexed: 12/14/2022] Open
Abstract
The host restriction factor tetherin inhibits virion release from infected cells and poses a significant barrier to successful zoonotic transmission of primate lentiviruses to humans. While most simian immunodeficiency viruses (SIV), including the direct precursors of human immunodeficiency virus type 1 (HIV-1) and HIV-2, use their Nef protein to counteract tetherin in their natural hosts, they fail to antagonize the human tetherin ortholog. Pandemic HIV-1 group M and epidemic group O strains overcame this hurdle by adapting their Vpu and Nef proteins, respectively, whereas HIV-2 group A uses its envelope (Env) glycoprotein to counteract human tetherin. Whether or how the remaining eight groups of HIV-2 antagonize this antiviral factor has remained unclear. Here, we show that Nef proteins from diverse groups of HIV-2 do not or only modestly antagonize human tetherin, while their ability to downmodulate CD3 and CD4 is highly conserved. Experiments in transfected cell lines and infected primary cells revealed that not only Env proteins of epidemic HIV-2 group A but also those of a circulating recombinant form (CRF01_AB) and rare groups F and I decrease surface expression of human tetherin and significantly enhance progeny virus release. Intriguingly, we found that many SIVsmm Envs also counteract human as well as smm tetherin. Thus, Env-mediated tetherin antagonism in different groups of HIV-2 presumably stems from a preadaptation of their SIVsmm precursors to humans. In summary, we identified a phenotypic trait of SIVsmm that may have facilitated its successful zoonotic transmission to humans and the emergence of HIV-2.IMPORTANCE HIV-2 groups A to I resulted from nine independent cross-species transmission events of SIVsmm to humans and differ considerably in their prevalence and geographic spread. Thus, detailed characterization of these viruses offers a valuable means to elucidate immune evasion mechanisms and human-specific adaptations determining viral spread. In a systematic comparison of rare and epidemic HIV-2 groups and their simian SIVsmm counterparts, we found that the ability of Nef to downmodulate the primary viral entry receptor CD4 and the T cell receptor CD3 is conserved, while effects on CD28, CD74, and major histocompatibility complex class I surface expression vary considerably. Furthermore, we show that not only the Env proteins of HIV-2 groups A, AB, F, and I but also those of some SIVsmm isolates antagonize human tetherin. This finding helps to explain why SIVsmm has been able to cross the species barrier to humans on at least nine independent occasions.
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14
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Kmiec D, Akbil B, Ananth S, Hotter D, Sparrer KMJ, Stürzel CM, Trautz B, Ayouba A, Peeters M, Yao Z, Stagljar I, Passos V, Zillinger T, Goffinet C, Sauter D, Fackler OT, Kirchhoff F. SIVcol Nef counteracts SERINC5 by promoting its proteasomal degradation but does not efficiently enhance HIV-1 replication in human CD4+ T cells and lymphoid tissue. PLoS Pathog 2018; 14:e1007269. [PMID: 30125328 PMCID: PMC6117100 DOI: 10.1371/journal.ppat.1007269] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 08/30/2018] [Accepted: 08/08/2018] [Indexed: 12/18/2022] Open
Abstract
SERINC5 is a host restriction factor that impairs infectivity of HIV-1 and other primate lentiviruses and is counteracted by the viral accessory protein Nef. However, the importance of SERINC5 antagonism for viral replication and cytopathicity remained unclear. Here, we show that the Nef protein of the highly divergent SIVcol lineage infecting mantled guerezas (Colobus guereza) is a potent antagonist of SERINC5, although it lacks the CD4, CD3 and CD28 down-modulation activities exerted by other primate lentiviral Nefs. In addition, SIVcol Nefs decrease CXCR4 cell surface expression, suppress TCR-induced actin remodeling, and counteract Colobus but not human tetherin. Unlike HIV-1 Nef proteins, SIVcol Nef induces efficient proteasomal degradation of SERINC5 and counteracts orthologs from highly divergent vertebrate species, such as Xenopus frogs and zebrafish. A single Y86F mutation disrupts SERINC5 and tetherin antagonism but not CXCR4 down-modulation by SIVcol Nef, while mutation of a C-proximal di-leucine motif has the opposite effect. Unexpectedly, the Y86F change in SIVcol Nef had little if any effect on viral replication and CD4+ T cell depletion in preactivated human CD4+ T cells and in ex vivo infected lymphoid tissue. However, SIVcol Nef increased virion infectivity up to 10-fold and moderately increased viral replication in resting peripheral blood mononuclear cells (PBMCs) that were first infected with HIV-1 and activated three or six days later. In conclusion, SIVcol Nef lacks several activities that are conserved in other primate lentiviruses and utilizes a distinct proteasome-dependent mechanism to counteract SERINC5. Our finding that evolutionarily distinct SIVcol Nefs show potent anti-SERINC5 activity supports a relevant role of SERINC5 antagonism for viral fitness in vivo. Our results further suggest this Nef function is particularly important for virion infectivity under conditions of limited CD4+ T cell activation. The accessory protein Nef promotes primate lentiviral replication and enhances the pathogenicity of HIV-1 by mechanisms of immune evasion and enhancing viral infectivity and replication. Here, we show that the evolutionarily most isolated primate lentivirus SIVcol lacks several otherwise conserved Nef functions. Nevertheless, SIVcol Nef potently antagonizes SERINC5, a recently discovered inhibitor of viral infectivity, by down-modulating it from the cell surface and inducing its proteasomal degradation. We identified Y86 in SIVcol Nef as a key determinant of SERINC5 antagonism. Efficient counteraction of SERINC5 did not increase HIV-1 replication in preactivated CD4+ T cells and in ex vivo infected lymphoid tissue but had modest enhancing effects when resting PBMCs were first infected and activated six days later. Evolution of high anti-SERINC5 activity by SIVcol Nef supports a relevant role of this antagonism in vivo, for instance by enhancing virion infectivity under conditions of limited T cell activation.
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Affiliation(s)
- Dorota Kmiec
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Bengisu Akbil
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Swetha Ananth
- Department of Infectious Diseases, Integrative Virology, CIID, University Hospital Heidelberg, Heidelberg, Germany
- German Center for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - Dominik Hotter
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | | | | | - Birthe Trautz
- Department of Infectious Diseases, Integrative Virology, CIID, University Hospital Heidelberg, Heidelberg, Germany
- German Center for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - Ahidjo Ayouba
- TransVIHMI, Institut de Recherche pour le Développement, University of Montpellier, INSERM, Montpellier, France
| | - Martine Peeters
- TransVIHMI, Institut de Recherche pour le Développement, University of Montpellier, INSERM, Montpellier, France
| | - Zhong Yao
- Donnelly Centre, University of Toronto, Ontario, Canada
| | - Igor Stagljar
- Donnelly Centre, University of Toronto, Ontario, Canada
- Departments of Biochemistry and Molecular Genetics, University of Toronto, Ontario, Canada
| | - Vânia Passos
- Institute of Virology, Hannover Medical School, Hannover, Germany
| | - Thomas Zillinger
- Institute of Clinical Chemistry and Clinical Pharmacology, University of Bonn, Bonn, Germany
| | | | - Daniel Sauter
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
| | - Oliver T. Fackler
- Department of Infectious Diseases, Integrative Virology, CIID, University Hospital Heidelberg, Heidelberg, Germany
- German Center for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany
- * E-mail:
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15
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Li W, Li C, Xia W, Li X. HLA-DQB1*06 and breadth of Nef core region-specific T-cell response are associated with slow disease progression in antiretroviral therapy-naive Chinese HIV-1 subtype B patients. Hum Vaccin Immunother 2018; 13:2341-2347. [PMID: 28771107 DOI: 10.1080/21645515.2017.1340138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Vaccines still are an important way to prevent and treat acquired immunodeficiency syndrome (AIDS). 1 For developing an effective T cell-based AIDS vaccine, it is critical to define the human leukocyte antigen (HLA) type and epitope that elicit the most potent responses. This study involved 29 antiretroviral therapy-naive and chronic human immunodeficiency virus (HIV)-1 subtype B-infected individuals. A polymerase chain reaction-sequence-specific primer was used to detect the HLA typing, and the enzyme-linked immunospot assay to quantify the T-cell immune function. The results showed that the HLA-DQB1*06-positive group had higher CD4 counts and lower viral load (VL) compared with the HLA-DQB1*06-negative group; A higher magnitude of HIV-1-specific T-cell response and breadth were observed in the HLA-DQB1*06-positive group; the T-cell response was proportional to VL (R2 = 0.488, P = 0.0368) in the HLA-DQB1*06-positive group. The total T-cell responses to HIV-1 Nef core region were quantified at the single-peptide level. Nine (90%) peptides were recognized in 18 (62.1%) individuals. The breath of Nef core region-specific T-cell response was correlated positively with CD4+ T cell count and inversely with VL, which improved disease outcomes. These data revealed that HLA-DQB1*06 had a protective effect on the course of HIV-1 and T-cell targeting of certain specific Nef epitopes, contributing to HIV-1 suppression. The results suggested the potential use of HLA-DQB1*06 and Nef core region in HIV-1 T-cell vaccine design.
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Affiliation(s)
- Weihua Li
- a YouAn Hospital , Capital Medical University , Beijing , China.,b Beijing Liver Disease Research Institute , Beijing , China
| | - Chuanyun Li
- a YouAn Hospital , Capital Medical University , Beijing , China
| | - Wei Xia
- a YouAn Hospital , Capital Medical University , Beijing , China
| | - Xiuhui Li
- a YouAn Hospital , Capital Medical University , Beijing , China
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16
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Joas S, Parrish EH, Gnanadurai CW, Lump E, Stürzel CM, Parrish NF, Learn GH, Sauermann U, Neumann B, Rensing KM, Fuchs D, Billingsley JM, Bosinger SE, Silvestri G, Apetrei C, Huot N, Garcia-Tellez T, Müller-Trutwin M, Hotter D, Sauter D, Stahl-Hennig C, Hahn BH, Kirchhoff F. Species-specific host factors rather than virus-intrinsic virulence determine primate lentiviral pathogenicity. Nat Commun 2018; 9:1371. [PMID: 29636452 PMCID: PMC5893559 DOI: 10.1038/s41467-018-03762-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 03/07/2018] [Indexed: 12/23/2022] Open
Abstract
HIV-1 causes chronic inflammation and AIDS in humans, whereas related simian immunodeficiency viruses (SIVs) replicate efficiently in their natural hosts without causing disease. It is currently unknown to what extent virus-specific properties are responsible for these different clinical outcomes. Here, we incorporate two putative HIV-1 virulence determinants, i.e., a Vpu protein that antagonizes tetherin and blocks NF-κB activation and a Nef protein that fails to suppress T cell activation via downmodulation of CD3, into a non-pathogenic SIVagm strain and test their impact on viral replication and pathogenicity in African green monkeys. Despite sustained high-level viremia over more than 4 years, moderately increased immune activation and transcriptional signatures of inflammation, the HIV-1-like SIVagm does not cause immunodeficiency or any other disease. These data indicate that species-specific host factors rather than intrinsic viral virulence factors determine the pathogenicity of primate lentiviruses.
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Affiliation(s)
- Simone Joas
- Institute of Molecular Virology, Ulm University Medical Center, 89081, Ulm, Germany
| | - Erica H Parrish
- Departments of Medicine and Microbiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, 372327, USA
| | - Clement W Gnanadurai
- Institute of Molecular Virology, Ulm University Medical Center, 89081, Ulm, Germany
- Department of Veterinary Pathology, University of Georgia, Athens, GA, 30602, USA
| | - Edina Lump
- Institute of Molecular Virology, Ulm University Medical Center, 89081, Ulm, Germany
| | - Christina M Stürzel
- Institute of Molecular Virology, Ulm University Medical Center, 89081, Ulm, Germany
| | - Nicholas F Parrish
- Departments of Medicine and Microbiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Surgery, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Gerald H Learn
- Departments of Medicine and Microbiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | | | | | | | - Dietmar Fuchs
- Division of Biological Chemistry, Biocenter Innsbruck Medical University, Center for Chemistry and Biomedicine, A-6020, Innsbruck, Austria
| | - James M Billingsley
- Emory Vaccine Center and Yerkes National Primate Research Center, Emory University, Atlanta, GA, 30322, USA
| | - Steven E Bosinger
- Emory Vaccine Center and Yerkes National Primate Research Center, Emory University, Atlanta, GA, 30322, USA
| | - Guido Silvestri
- Emory Vaccine Center and Yerkes National Primate Research Center, Emory University, Atlanta, GA, 30322, USA
| | - Cristian Apetrei
- WA Center for Vaccine Research, University of Pittsburgh, Pittsburgh, PA, 15261, USA
| | - Nicolas Huot
- Institut Pasteur, Unité HIV, Inflammation and Persistence, Paris, 75015, France
- Vaccine Research Institute, Hôpital Henri Mondor, Créteil, 94010, France
| | | | | | - Dominik Hotter
- Institute of Molecular Virology, Ulm University Medical Center, 89081, Ulm, Germany
| | - Daniel Sauter
- Institute of Molecular Virology, Ulm University Medical Center, 89081, Ulm, Germany
| | | | - Beatrice H Hahn
- Departments of Medicine and Microbiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, 89081, Ulm, Germany.
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17
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Maintenance of AP-2-Dependent Functional Activities of Nef Restricts Pathways of Immune Escape from CD8 T Lymphocyte Responses. J Virol 2018; 92:JVI.01822-17. [PMID: 29237831 DOI: 10.1128/jvi.01822-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 12/02/2017] [Indexed: 01/28/2023] Open
Abstract
Nef-specific CD8+ T lymphocytes (CD8TL) are linked to extraordinary control of primate lentiviral replication, but the mechanisms underlying their efficacy remain largely unknown. The immunodominant, Mamu-B*017:01+-restricted Nef195-203MW9 epitope in SIVmac239 partially overlaps a sorting motif important for interactions with host AP-2 proteins and, hence, downmodulation of several host proteins, including Tetherin (CD317/BST-2), CD28, CD4, SERINC3, and SERINC5. We reasoned that CD8TL-driven evolution in this epitope might compromise Nef's ability to modulate these important molecules. Here, we used deep sequencing of SIV from nine B*017:01+ macaques throughout infection with SIVmac239 to characterize the patterns of viral escape in this epitope and then assayed the impacts of these variants on Nef-mediated modulation of multiple host molecules. Acute variation in multiple Nef195-203MW9 residues significantly compromised Nef's ability to downregulate surface Tetherin, CD4, and CD28 and reduced its ability to prevent SERINC5-mediated reduction in viral infectivity but did not impact downregulation of CD3 or major histocompatibility complex class I, suggesting the selective disruption of immunomodulatory pathways involving Nef AP-2 interactions. Together, our data illuminate a pattern of viral escape dictated by a selective balance to maintain AP-2-mediated downregulation while evading epitope-specific CD8TL responses. These data could shed light on mechanisms of both CD8TL-driven viral control generally and on Mamu-B*017:01-mediated viral control specifically.IMPORTANCE A rare subset of humans infected with HIV-1 and macaques infected with SIV can control the virus without aid of antiviral medications. A common feature of these individuals is the ability to mount unusually effective CD8 T lymphocyte responses against the virus. One of the most formidable aspects of HIV is its ability to evolve to evade immune responses, particularly CD8 T lymphocytes. We show that macaques that target a specific peptide in the SIV Nef protein are capable of better control of the virus and that, as the virus evolves to escape this response, it does so at a cost to specific functions performed by the Nef protein. Our results help show how the virus can be controlled by an immune response, which could help in designing effective vaccines.
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18
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Heusinger E, Kirchhoff F. Primate Lentiviruses Modulate NF-κB Activity by Multiple Mechanisms to Fine-Tune Viral and Cellular Gene Expression. Front Microbiol 2017; 8:198. [PMID: 28261165 PMCID: PMC5306280 DOI: 10.3389/fmicb.2017.00198] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 01/27/2017] [Indexed: 12/15/2022] Open
Abstract
The transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) plays a complex role during the replication of primate lentiviruses. On the one hand, NF-κB is essential for induction of efficient proviral gene expression. On the other hand, this transcription factor contributes to the innate immune response and induces expression of numerous cellular antiviral genes. Recent data suggest that primate lentiviruses cope with this challenge by boosting NF-κB activity early during the replication cycle to initiate Tat-driven viral transcription and suppressing it at later stages to minimize antiviral gene expression. Human and simian immunodeficiency viruses (HIV and SIV, respectively) initially exploit their accessory Nef protein to increase the responsiveness of infected CD4+ T cells to stimulation. Increased NF-κB activity initiates Tat expression and productive replication. These events happen quickly after infection since Nef is rapidly expressed at high levels. Later during infection, Nef proteins of HIV-2 and most SIVs exert a very different effect: by down-modulating the CD3 receptor, an essential factor for T cell receptor (TCR) signaling, they prevent stimulation of CD4+ T cells via antigen-presenting cells and hence suppress further induction of NF-κB and an effective antiviral immune response. Efficient LTR-driven viral transcription is maintained because it is largely independent of NF-κB in the presence of Tat. In contrast, human immunodeficiency virus type 1 (HIV-1) and its simian precursors have lost the CD3 down-modulation function of Nef and use the late viral protein U (Vpu) to inhibit NF-κB activity by suppressing its nuclear translocation. In this review, we discuss how HIV-1 and other primate lentiviruses might balance viral and antiviral gene expression through a tight temporal regulation of NF-κB activity throughout their replication cycle.
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Affiliation(s)
- Elena Heusinger
- Institute of Molecular Virology, Ulm University Medical Center Ulm, Germany
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center Ulm, Germany
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19
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Darcis G, Van Driessche B, Bouchat S, Kirchhoff F, Van Lint C. Molecular Control of HIV and SIV Latency. Curr Top Microbiol Immunol 2017; 417:1-22. [PMID: 29071474 DOI: 10.1007/82_2017_74] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The HIV latent reservoirs are considered as the main hurdle to viral eradication. Numerous mechanisms lead to the establishment of HIV latency and act at the transcriptional and post-transcriptional levels. A better understanding of latency is needed in order to ultimately achieve a cure for HIV. The mechanisms underlying latency vary between patients, tissues, anatomical compartments, and cell types. From this point of view, simian immunodeficiency virus (SIV) infection and the use of nonhuman primate (NHP) models that recapitulate many aspects of HIV-associated latency establishment and disease progression are essential tools since they allow extensive tissue sampling as well as a control of infection parameters (virus type, dose, route, and time).
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Affiliation(s)
- Gilles Darcis
- Service of Molecular Virology, Département de Biologie Moléculaire (DBM), Université Libre de Bruxelles (ULB), Rue des Professeurs Jeener et Brachet 12, 6041, Gosselies, Belgium.,Service des Maladies Infectieuses, Université de Liège, CHU de Liège, Domaine Universitaire du Sart-Tilman, B35, 4000, Liège, Belgium.,Laboratory of Experimental Virology, Department of Medical Microbiology, Academic Medical Center of the University of Amsterdam, Meibergdreef 15, 1105, AZ, Amsterdam, The Netherlands
| | - Benoit Van Driessche
- Service of Molecular Virology, Département de Biologie Moléculaire (DBM), Université Libre de Bruxelles (ULB), Rue des Professeurs Jeener et Brachet 12, 6041, Gosselies, Belgium
| | - Sophie Bouchat
- Service of Molecular Virology, Département de Biologie Moléculaire (DBM), Université Libre de Bruxelles (ULB), Rue des Professeurs Jeener et Brachet 12, 6041, Gosselies, Belgium
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, Meyerhofstraße 1, 89081, Ulm, Germany
| | - Carine Van Lint
- Service of Molecular Virology, Département de Biologie Moléculaire (DBM), Université Libre de Bruxelles (ULB), Rue des Professeurs Jeener et Brachet 12, 6041, Gosselies, Belgium.
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21
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Acute Viral Escape Selectively Impairs Nef-Mediated Major Histocompatibility Complex Class I Downmodulation and Increases Susceptibility to Antiviral T Cells. J Virol 2015; 90:2119-26. [PMID: 26637459 DOI: 10.1128/jvi.01975-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 11/24/2015] [Indexed: 01/29/2023] Open
Abstract
Nef-specific CD8(+) T lymphocytes (CD8TL) are associated with control of simian immunodeficiency virus (SIV) despite extensive nef variation between and within animals. Deep viral sequencing of the immunodominant Mamu-B*017:01-restricted Nef165-173IW9 epitope revealed highly restricted evolution. A common acute escape variant, T170I, unexpectedly and uniquely degraded Nef's major histocompatibility complex class I (MHC-I) downregulatory capacity, rendering the virus more vulnerable to CD8TL targeting other epitopes. These data aid in a mechanistic understanding of Nef functions and suggest means of immunity-mediated control of lentivirus replication.
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Abstract
UNLABELLED The role of the accessory viral Nef protein as a multifunctional manipulator of the host cell that is required for effective replication of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) in vivo is well established. It is unknown, however, whether Nef manipulates all or just specific subsets of CD4(+) T cells, which are the main targets of virus infection and differ substantially in their state of activation and importance for a functional immune system. Here, we analyzed the effect of Nef proteins differing in their T cell receptor (TCR)-CD3 downmodulation function in HIV-infected human lymphoid aggregate cultures and peripheral blood mononuclear cells. We found that Nef efficiently downmodulates TCR-CD3 in naive and memory CD4(+) T cells and protects the latter against apoptosis. In contrast, highly proliferative CD45RA(+) CD45RO(+) CD4(+) T cells were main producers of infectious virus but largely refractory to TCR-CD3 downmodulation. Such T cell subset-specific differences were also observed for Nef-mediated modulation of CD4 but not for enhancement of virion infectivity. Our results indicate that Nef predominantly modulates surface receptors on CD4(+) T cell subsets that are not already fully permissive for viral replication. As a consequence, Nef-mediated downmodulation of TCR-CD3, which distinguishes most primate lentiviruses from HIV type 1 (HIV-1) and its vpu-containing simian precursors, may promote a selective preservation of central memory CD4(+) T cells, which are critical for the maintenance of a functional immune system. IMPORTANCE The Nef proteins of human and simian immunodeficiency viruses manipulate infected CD4(+) T cells in multiple ways to promote viral replication and immune evasion in vivo. Here, we show that some effects of Nef are subset specific. Downmodulation of CD4 and TCR-CD3 is highly effective in central memory CD4(+) T cells, and the latter Nef function protects this T cell subset against apoptosis. In contrast, highly activated/proliferating CD4(+) T cells are largely refractory to receptor downmodulation but are main producers of infectious HIV-1. Nef-mediated enhancement of virion infectivity, however, was observed in all T cell subsets examined. Our results provide new insights into how primate lentiviruses manipulate their target cells and suggest that the TCR-CD3 downmodulation function of Nef may promote a selective preservation of memory CD4(+) T cells, which are critical for immune function, but has little effect on activated/proliferating CD4(+) T cells, which are the main targets for viral replication.
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Lülf S, Matz J, Rouyez MC, Järviluoma A, Saksela K, Benichou S, Geyer M. Structural basis for the inhibition of HIV-1 Nef by a high-affinity binding single-domain antibody. Retrovirology 2014; 11:24. [PMID: 24620746 PMCID: PMC4007562 DOI: 10.1186/1742-4690-11-24] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Accepted: 03/04/2014] [Indexed: 04/01/2023] Open
Abstract
Background The HIV-1 Nef protein is essential for AIDS pathogenesis by its interaction with host cell surface receptors and signaling factors. Despite its critical role as a virulence factor Nef is not targeted by current antiviral strategies. Results We have determined the crystal structure of the complex formed by a camelid single-domain antibody fragment, termed sdAb19, bound to HIV-1 Nef together with a stabilizing SH3 domain. sdAb19 forms a stoichiometric 1:1 complex with Nef and binds to a conformationally conserved surface at the C-terminus of Nef that overlaps with functionally important interaction sites involved in Nef-induced perturbations of signaling and trafficking pathways. The antibody fragment binds Nef with low nanomolar affinity, which could be attenuated to micromolar affinity range by site-directed mutagenesis of key interaction residues in sdAb19. Fusion of the SH3 domain to sdAb19, termed Neffin, leads to a significantly increased affinity for Nef and formation of a stoichiometric 2:2 Nef–Neffin complex. The 19 kDa Neffin protein inhibits all functions of Nef as CD4 and MHC-I downregulation, association with Pak2, and the increase in virus infectivity and replication. Conclusions Together, sdAb19 and Neffin thus represent efficient tools for the rational development of antiviral strategies against HIV-1 Nef.
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Affiliation(s)
| | | | | | | | | | | | - Matthias Geyer
- Center of Advanced European Studies and Research, Group Physical Biochemistry, Bonn, Germany.
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Heigele A, Camerini D, van't Wout AB, Kirchhoff F. Viremic long-term nonprogressive HIV-1 infection is not associated with abnormalities in known Nef functions. Retrovirology 2014; 11:13. [PMID: 24495362 PMCID: PMC3927655 DOI: 10.1186/1742-4690-11-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Accepted: 01/26/2014] [Indexed: 11/12/2022] Open
Abstract
Background A small minority of HIV-1-infected individuals show low levels of immune activation and do not develop immunodeficiency despite high viral loads. Since the accessory viral Nef protein modulates T cell activation and plays a key role in the pathogenesis of AIDS, we investigated whether specific properties of Nef may be associated with this highly unusual clinical outcome of HIV-1 infection. Findings Comprehensive functional analyses of sequential HIV-1 strains from three viremic long-term non-progressors (VNP) showed that they encode full-length Nef proteins that are capable of modulating CD4, CD28, CD8ß, MHC-I and CD74 cell surface expression. Similar to Nef proteins from HIV-1-infected individuals with progressive infection (P-Nefs) and unlike Nefs from simian immunodeficiency viruses (SIVs) that do not cause chronic immune activation and disease in their natural simian hosts, VNP-Nefs were generally unable to down-modulate TCR-CD3 cell surface expression to block T cell activation and apoptosis. On average, VNP-Nefs suppressed NF-AT activation less effectively than P-Nefs and were slightly less active in enhancing NF-κB activity. Finally, we found that VNP-Nefs increased virion infectivity and enhanced HIV-1 replication and cytopathicity in primary human cells and in ex vivo infected lymphoid tissues. Conclusions Our results show that nef alleles from VNPs and progressors of HIV-1 infection show only modest differences in established functions. Thus, the lack of chronic immune activation and disease progression in HIV-1-infected VNPs is apparently not associated with unusual functional properties of the accessory viral Nef protein.
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Affiliation(s)
| | | | | | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical Center, Ulm, Germany.
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Schmökel J, Li H, Shabir A, Yu H, Geyer M, Silvestri G, Sodora DL, Hahn BH, Kirchhoff F. Link between primate lentiviral coreceptor usage and Nef function. Cell Rep 2013; 5:997-1009. [PMID: 24268781 PMCID: PMC4133736 DOI: 10.1016/j.celrep.2013.10.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 10/02/2013] [Accepted: 10/17/2013] [Indexed: 12/02/2022] Open
Abstract
Simian immunodeficiency virus (SIVsmm) infection of sooty mangabeys (Cercocebus atys) is characterized by stable CD4+ T cell counts despite high plasma levels of CCR5-tropic viruses. However, in rare instances, SIVsmm acquires CXCR4 coreceptor tropism and causes severe CD4+ T cell depletion, albeit without clinical signs of immunodeficiency. Here, we show that CXCR4-tropic SIVsmm strains lost their ability to downmodulate TCR-CD3 by evolving unusual Nef mutations that initially reduced (I132V) and subsequently disrupted (I123L and L146F) interaction with the CD3 ζ chain. This coevolution of Env and Nef function suggests that CD3 downmodulation is advantageous for viral replication in activated CCR5+ memory T cells, but not in resting naive CXCR4+ T cells that have not yet undergone TCR-CD3-mediated stimulation. This may explain why HIV-1, which generally lacks the CD3 downmodulation function, commonly switches to CXCR4 usage, whereas this is extremely rare for SIV strains that have retained this Nef activity.
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MESH Headings
- Animals
- Antigen-Presenting Cells/immunology
- CD3 Complex/biosynthesis
- CD3 Complex/immunology
- CD4-Positive T-Lymphocytes/immunology
- Cells, Cultured
- Cercocebus/virology
- Gene Products, env/genetics
- Gene Products, env/immunology
- Gene Products, nef/genetics
- Gene Products, nef/immunology
- HIV Infections/genetics
- HIV Infections/immunology
- HIV-1/genetics
- HIV-1/immunology
- HIV-2/genetics
- HIV-2/immunology
- Immunologic Memory
- Lymphocyte Activation/immunology
- Lymphocyte Count
- Molecular Sequence Data
- Protein Structure, Tertiary
- Receptor-CD3 Complex, Antigen, T-Cell/immunology
- Receptors, CCR5/immunology
- Receptors, CXCR4/immunology
- Simian Acquired Immunodeficiency Syndrome/genetics
- Simian Acquired Immunodeficiency Syndrome/immunology
- Simian Immunodeficiency Virus/genetics
- Simian Immunodeficiency Virus/immunology
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Affiliation(s)
- Jan Schmökel
- Institute of Molecular Virology, University of Ulm, 89069 Ulm, Germany
| | - Hui Li
- Department of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Asma Shabir
- Institute of Molecular Virology, University of Ulm, 89069 Ulm, Germany
| | - Hangxing Yu
- Institute of Molecular Virology, University of Ulm, 89069 Ulm, Germany
| | - Matthias Geyer
- Center of Advanced European Studies and Research (CAESAR), Physical Biochemistry Group, 53175 Bonn, Germany
| | - Guido Silvestri
- Yerkes Regional Primate Research Center, Emory University, Atlanta, GA 30322, USA
| | - Donald L Sodora
- Seattle Biomedical Research Institute, Seattle, WA 98109, USA
| | - Beatrice H Hahn
- Department of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Microbiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Frank Kirchhoff
- Institute of Molecular Virology, University of Ulm, 89069 Ulm, Germany.
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Markle TJ, Philip M, Brockman MA. HIV-1 Nef and T-cell activation: a history of contradictions. Future Virol 2013; 8. [PMID: 24187576 DOI: 10.2217/fvl.13.20] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
HIV-1 Nef is a multifunctional viral protein that contributes to higher plasma viremia and more rapid disease progression. Nef appears to accomplish this, in part, through modulation of T-cell activation; however, the results of these studies over the past 25 years have been inconsistent. Here, the history of contradictory observations related to HIV-1 Nef and its ability to modulate T-cell activation is reviewed, and recent reports that may help to explain Net's apparent ability to both inhibit and activate T cells are highlighted.
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Affiliation(s)
- Tristan J Markle
- Simon Fraser University, 8888 University Drive, Burnaby BC V5A 1S6, Canada
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27
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Yu H, Usmani SM, Borch A, Krämer J, Stürzel CM, Khalid M, Li X, Krnavek D, van der Ende ME, Osterhaus AD, Gruters RA, Kirchhoff F. The efficiency of Vpx-mediated SAMHD1 antagonism does not correlate with the potency of viral control in HIV-2-infected individuals. Retrovirology 2013; 10:27. [PMID: 23497283 PMCID: PMC3599662 DOI: 10.1186/1742-4690-10-27] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 02/22/2013] [Indexed: 11/30/2022] Open
Affiliation(s)
- Hangxing Yu
- Institute of Molecular Virology, Ulm University Medical Center, Ulm 89081, Germany
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28
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Current World Literature. Curr Opin Rheumatol 2013; 25:275-83. [DOI: 10.1097/bor.0b013e32835eb755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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29
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Nyamweya S, Hegedus A, Jaye A, Rowland-Jones S, Flanagan KL, Macallan DC. Comparing HIV-1 and HIV-2 infection: Lessons for viral immunopathogenesis. Rev Med Virol 2013; 23:221-40. [PMID: 23444290 DOI: 10.1002/rmv.1739] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Revised: 11/18/2012] [Accepted: 11/20/2012] [Indexed: 12/18/2022]
Abstract
HIV-1 and HIV-2 share many similarities including their basic gene arrangement, modes of transmission, intracellular replication pathways and clinical consequences: both result in AIDS. However, HIV-2 is characterised by lower transmissibility and reduced likelihood of progression to AIDS. The underlying mechanistic differences between these two infections illuminate broader issues of retroviral pathogenesis, which remain incompletely understood. Comparisons between these two infections from epidemiological, clinical, virologic and immunologic viewpoints provide a basis for hypothesis generation and testing in this 'natural experiment' in viral pathogenesis. In terms of epidemiology, HIV-2 remains largely confined to West Africa, whereas HIV-1 extends worldwide. Clinically, HIV-2 infected individuals seem to dichotomise, most remaining long-term non-progressors, whereas most HIV-1 infected individuals progress. When clinical progression occurs, both diseases demonstrate very similar pathological processes, although progression in HIV-2 occurs at higher CD4 counts. Plasma viral loads are consistently lower in HIV-2, as are average levels of immune activation. Significant differences exist between the two infections in all components of the immune system. For example, cellular responses to HIV-2 tend to be more polyfunctional and produce more IL-2; humoral responses appear broader with lower magnitude intratype neutralisation responses; innate responses appear more robust, possibly through differential effects of tripartite motif protein isoform 5 alpha. Overall, the immune response to HIV-2 appears more protective against disease progression suggesting that pivotal immune factors limit viral pathology. If such immune responses could be replicated or induced in HIV-1 infected patients, they might extend survival and reduce requirements for antiretroviral therapy.
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