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Interferon-alpha treatment rapidly clears Hepatitis E virus infection in humanized mice. Sci Rep 2017; 7:8267. [PMID: 28811492 PMCID: PMC5557905 DOI: 10.1038/s41598-017-07434-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 06/27/2017] [Indexed: 12/17/2022] Open
Abstract
Antiviral treatment options for chronic Hepatitis E Virus (HEV) infections are limited and immunological determinants of viral persistence remain largely unexplored. We studied the antiviral potency of pegylated interferon-α (pegIFNα) against HEV infections in humanized mice and modelled intrahepatic interferon stimulated gene (ISG) responses. Human gene expression levels in humanized mouse livers were analyzed by qPCR and Nanostring. Human CXCL10 was measured in mouse serum. HEV genotype 3 (gt3) infections were cleared from liver and feces within 8 pegIFNα doses in all mice and relapsed after a single pegIFNα injection in only half of treated animals. Rapid viral clearance by pegIFNα was confirmed in HEV gt1, but not in Hepatitis B Virus infected animals. No ISG induction was observed in untreated HEV gt3 and gt1 infected humanized livers compared to control chimeric mice, irrespective of the human hepatocyte donor, viral isolate or HEV infection duration. Human specific ISG transcript levels in mouse liver increased significantly after pegIFNα treatment and induced high circulating human CXCL10 in mouse serum. In conclusion, HEV gt1 and gt3 infections do not elicit innate intrahepatic immune responses and remain highly sensitive to pegIFNα in immunocompromised humanized mice.
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Roy N, Pacini G, Berlioz-Torrent C, Janvier K. Characterization of E3 ligases involved in lysosomal sorting of the HIV-1 restriction factor BST2. J Cell Sci 2017; 130:1596-1611. [PMID: 28320822 PMCID: PMC5450231 DOI: 10.1242/jcs.195412] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 02/17/2017] [Indexed: 12/17/2022] Open
Abstract
The cellular protein BST2 (also known as tetherin) acts as a major intrinsic antiviral protein that prevents the release of enveloped viruses by trapping nascent viral particles at the surface of infected cells. Viruses have evolved specific strategies to displace BST2 from viral budding sites in order to promote virus egress. In HIV-1, the accessory protein Vpu counters BST2 antiviral activity and promotes sorting of BST2 for lysosomal degradation. Vpu increases polyubiquitylation of BST2, a post-translation modification required for Vpu-induced BST2 downregulation, through recruitment of the E3 ligase complex SCF adaptors β-TrCP1 and β-TrCP2 (two isoforms encoded by BTRC and FBXW11, respectively). Herein, we further investigate the role of the ubiquitylation machinery in the lysosomal sorting of BST2. Using a small siRNA screen, we highlighted two additional regulators of BST2 constitutive ubiquitylation and sorting to the lysosomes: the E3 ubiquitin ligases NEDD4 and MARCH8. Interestingly, Vpu does not hijack the cellular machinery that is constitutively involved in BST2 ubiquitylation to sort BST2 for degradation in the lysosomes but instead promotes the recognition of BST2 by β-TrCP proteins. Altogether, our results provide further understanding of the mechanisms underlying BST2 turnover in cells. Highlighted Article: We identify two E3 ubiquitin ligases, NEDD4 and MARCH8, as regulators of BST2 (tetherin) – a protein that restricts viral release; we thus provide further understanding of the mechanisms underlying BST2 turnover in cells.
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Affiliation(s)
- Nicolas Roy
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Grégory Pacini
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Clarisse Berlioz-Torrent
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Katy Janvier
- Inserm, U1016, Institut Cochin, Paris, France .,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
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Single Amino Acid Substitution N659D in HIV-2 Envelope Glycoprotein (Env) Impairs Viral Release and Hampers BST-2 Antagonism. Viruses 2016; 8:v8100285. [PMID: 27754450 PMCID: PMC5086617 DOI: 10.3390/v8100285] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 09/30/2016] [Accepted: 10/06/2016] [Indexed: 12/11/2022] Open
Abstract
BST-2 or tetherin is a host cell restriction factor that prevents the budding of enveloped viruses at the cell surface, thus impairing the viral spread. Several countermeasures to evade this antiviral factor have been positively selected in retroviruses: the human immunodeficiency virus type 2 (HIV-2) relies on the envelope glycoprotein (Env) to overcome BST-2 restriction. The Env gp36 ectodomain seems involved in this anti-tetherin activity, however residues and regions interacting with BST-2 are not clearly defined. Among 32 HIV-2 ROD Env mutants tested, we demonstrated that the asparagine residue at position 659 located in the gp36 ectodomain is mandatory to exert the anti-tetherin function. Viral release assays in cell lines expressing BST-2 showed a loss of viral release ability for the HIV-2 N659D mutant virus compared to the HIV-2 wild type virus. In bst-2 inactivated H9 cells, those differences were lost. Subtilisin treatment of infected cells demonstrated that the N659D mutant was more tethered at the cell surface. Förster resonance energy transfer (FRET) experiments confirmed a direct molecular link between Env and BST-2 and highlighted an inability of the mutant to bind BST-2. We also tested a virus presenting a truncation of 109 amino acids at the C-terminal part of Env, a cytoplasmic tail partial deletion that is spontaneously selected in vitro. Interestingly, viral release assays and FRET experiments indicated that a full Env cytoplasmic tail was essential in BST-2 antagonism. In HIV-2 infected cells, an efficient Env-mediated antagonism of BST-2 is operated through an intermolecular link involving the asparagine 659 residue as well as the C-terminal part of the cytoplasmic tail.
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Liu Y, Li M, Zhang D, Zhang M, Hu Q. HSV-2 glycoprotein gD targets the CC domain of tetherin and promotes tetherin degradation via lysosomal pathway. Virol J 2016; 13:154. [PMID: 27630089 PMCID: PMC5024446 DOI: 10.1186/s12985-016-0610-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/08/2016] [Indexed: 11/16/2022] Open
Abstract
Background HSV-2 is the major cause of genital herpes. We previously demonstrated that the host viral restriction factor tetherin restricts HSV-2 release and is antagonized by several HSV-2 glycoproteins. However, the mechanisms underlying HSV-2 glycoproteins mediated counteraction of tetherin remain unclear. In this study, we investigated whether tetherin restricts the cell-to-cell spread of HSV-2 and the mechanisms underlying HSV-2 gD mediated antagonism of tetherin. Methods Infectious center assays were used to test whether tetherin could affect cell-to-cell spread of HSV-2. Coimmunoprecipitation assays were performed to map the tetherin domains required for HSV-2 gD-mediated downregulation. Immunoflurence assays were performed to detect the accumulation of tetherin in lysosomes or proteasomes. All experiments were repeated for at least three times and the data were performed statistical analysis. Results 1) Tetherin restricts cell-to-cell spread of HSV-2; 2) HSV-2 gD specifically interacts with the CC domain of tetherin; 3) HSV-2 gD promotes tetherin to the lysosomal degradation pathway. Conclusions Tetherin not only restricts HSV-2 release but also its cell-to-cell spread. In turn, HSV-2 gD targets the CC domain of tetherin and promotes its degradation in the lysosome. Findings in this study have increased our understanding of tetherin restriction and viral countermeasures.
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Affiliation(s)
- Yalan Liu
- State Key Laboratory of Virology, Chinese Academy of Sciences, Wuhan Institute of Virology, Wuhan, 430071, China.
| | - Mei Li
- State Key Laboratory of Virology, Chinese Academy of Sciences, Wuhan Institute of Virology, Wuhan, 430071, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Di Zhang
- State Key Laboratory of Virology, Chinese Academy of Sciences, Wuhan Institute of Virology, Wuhan, 430071, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Mudan Zhang
- State Key Laboratory of Virology, Chinese Academy of Sciences, Wuhan Institute of Virology, Wuhan, 430071, China
| | - Qinxue Hu
- State Key Laboratory of Virology, Chinese Academy of Sciences, Wuhan Institute of Virology, Wuhan, 430071, China.,Institute for Infection and Immunity, St George's University of London, London, SW17 0RE, UK
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Shih C, Chou SF, Yang CC, Huang JY, Choijilsuren G, Jhou RS. Control and Eradication Strategies of Hepatitis B Virus. Trends Microbiol 2016; 24:739-749. [DOI: 10.1016/j.tim.2016.05.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Revised: 05/04/2016] [Accepted: 05/23/2016] [Indexed: 02/07/2023]
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56
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The Evolutionary Histories of Antiretroviral Proteins SERINC3 and SERINC5 Do Not Support an Evolutionary Arms Race in Primates. J Virol 2016; 90:8085-9. [PMID: 27356902 DOI: 10.1128/jvi.00972-16] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 06/23/2016] [Indexed: 01/06/2023] Open
Abstract
UNLABELLED Molecular evolutionary arms races between viruses and their hosts are important drivers of adaptation. These Red Queen dynamics have been frequently observed in primate retroviruses and their antagonists, host restriction factor genes, such as APOBEC3F/G, TRIM5-α, SAMHD1, and BST-2. Host restriction factors have experienced some of the most intense and pervasive adaptive evolution documented in primates. Recently, two novel host factors, SERINC3 and SERINC5, were identified as the targets of HIV-1 Nef, a protein crucial for the optimal infectivity of virus particles. Here, we compared the evolutionary fingerprints of SERINC3 and SERINC5 to those of other primate restriction factors and to a set of other genes with diverse functions. SERINC genes evolved in a manner distinct from the canonical arms race dynamics seen in the other restriction factors. Despite their antiviral activity against HIV-1 and other retroviruses, SERINC3 and SERINC5 have a relatively uneventful evolutionary history in primates. IMPORTANCE Restriction factors are host proteins that block viral infection and replication. Many viruses, like HIV-1 and related retroviruses, evolved accessory proteins to counteract these restriction factors. The importance of these interactions is evidenced by the intense adaptive selection pressures that dominate the evolutionary histories of both the host and viral genes involved in this so-called arms race. The dynamics of these arms races can point to mechanisms by which these viral infections can be prevented. Two human genes, SERINC3 and SERINC5, were recently identified as targets of an HIV-1 accessory protein important for viral infectivity. Unexpectedly, we found that these SERINC genes, unlike other host restriction factor genes, show no evidence of a recent evolutionary arms race with viral pathogens.
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MT1-MMP Inhibits the Activity of Bst-2 via Their Cytoplasmic Domains Dependent Interaction. Int J Mol Sci 2016; 17:ijms17060818. [PMID: 27240342 PMCID: PMC4926352 DOI: 10.3390/ijms17060818] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Revised: 05/12/2016] [Accepted: 05/16/2016] [Indexed: 01/30/2023] Open
Abstract
Bst-2 (bone marrow stromal cell antigen 2) is a type II membrane protein, and it acts as a tetherin to inhibit virion releasing from infectious cells. Membrane type-1 matrix metalloproteinase (MT1-MMP) is a protease. It plays a pivotal role in cellular growth and migration by activating proMMP-2 into active MMP2. Our results here elaborate that MT1-MMP inhibits the tetherin activity of Bst-2 by interacting with Bst-2, and the cytoplasmic domains of both Bst-2 and MT1-MMP play critical roles within this interaction. Based on our experimental data, the assays for virion release and co-immunoprecipitation have clearly demonstrated that the activity of Bst-2 is markedly inhibited by MT1-MMP via their interaction; and both the N-terminal domain of Bst-2 and the C-terminal domain of MT1-MMP are important in the interaction. Immunostaining and Confocal Microscopy assay shows that MT1-MMP interacts with Bst-2 to form granular particles trafficking into cytoplasm from membrane and, finally, results in Bst-2 and MT1-MMP both being inhibited. In addition, mutant experiments elucidate that the N-terminal domain of Bst-2 is not only important in relating to the activity of Bst-2 itself, but is important for inhibiting the MT1-MMP/proMMP2/MMP2 pathway. These findings suggest that MT1-MMP is a novel inhibitor of Bst-2 in MT1-MMP expressed cell lines and also indicate that both the N-terminal domain of Bst-2 and the C-terminal domain of MT1-MMP are crucial in down-regulation.
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58
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Nishitsuji H, Sugiyama R, Abe M, Takaku H. ATP1B3 Protein Modulates the Restriction of HIV-1 Production and Nuclear Factor κ Light Chain Enhancer of Activated B Cells (NF-κB) Activation by BST-2. J Biol Chem 2015; 291:4754-62. [PMID: 26694617 DOI: 10.1074/jbc.m115.679357] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Indexed: 11/06/2022] Open
Abstract
Here, we identify ATP1B3 and fibrillin-1 as novel BST-2-binding proteins. ATP1B3 depletion in HeLa cells (BST-2-positive cells), but not 293T cells (BST-2-negative cells), induced the restriction of HIV-1 production in a BST-2-dependent manner. In contrast, fibrillin-1 knockdown reduced HIV-1 production in 293T and HeLa cells in a BST-2-independent manner. Moreover, NF-κB activation was enhanced by siATP1B3 treatment in HIV-1- and HIV-1ΔVpu-infected HeLa cells. In addition, ATP1B3 silencing induced high level BST-2 expression on the surface of HeLa cells. These results indicate that ATP1B3 is a co-factor that accelerates BST-2 degradation and reduces BST-2-mediated restriction of HIV-1 production and NF-κB activation.
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Affiliation(s)
- Hironori Nishitsuji
- From the Research Center for Hepatitis and Immunology, National Center for Global Health and Medicine, Ichikawa, Chiba 272-8516
| | - Ryuichi Sugiyama
- the Department of Life and Environmental Sciences and the Department of Microbiology, Yokohama City University School of Medicine, Kanagawa 236-0004, Japan
| | - Makoto Abe
- the Department of Life and Environmental Sciences and
| | - Hiroshi Takaku
- the Department of Life and Environmental Sciences and Research Institute, Chiba Institute of Technology, 2-17-1 Tsudanuma, Narashino-shi, Chiba 275-0016, Japan, and
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Mussil B, Javed A, Töpfer K, Sauermann U, Sopper S. Increased BST2 expression during simian immunodeficiency virus infection is not a determinant of disease progression in rhesus monkeys. Retrovirology 2015; 12:92. [PMID: 26554913 PMCID: PMC4641394 DOI: 10.1186/s12977-015-0219-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 10/23/2015] [Indexed: 12/21/2022] Open
Abstract
Background Bone marrow stromal cell antigen 2 (BST2), also known as tetherin, HM1.24 or CD317 represents a type 2 integral membrane protein, which has been described to restrict the production of some enveloped viruses by inhibiting the virus release from the cell surface. This innate antiviral mechanism is counteracted by the HIV-1 viral factor Vpu, targeting BST2 for cellular degradation. Since antiviral BST2 activity has been mainly confirmed by in vitro data, we investigated its role in vivo on the disease progression using the SIV/macaque model for AIDS. We determined BST2 expression in PBMC and leukocyte subsets of uninfected and SIV-infected rhesus macaques by real-time PCR and flow cytometry and correlated it with disease progression and viral load. Results Compared to pre-infection levels, we found increased BST2 expression in PBMC, purified CD4+ lymphocytes and CD14+ monocytes of SIV-infected animals, which correlated with viral load. Highest BST2 levels were found in progressors and lowest levels comparable to uninfected macaques were observed in long-term non-progressors (LTNPs). During acute viremia, BST2 mRNA increased in parallel with MX1, a prototype interferon-stimulated gene. This association was maintained during the whole disease course. Conclusion The detected relationship between BST2 expression and viral load as well as with MX1 indicate a common regulation by the interferon response and suggest rather limited influence of BST2 in vivo on the disease outcome. Electronic supplementary material The online version of this article (doi:10.1186/s12977-015-0219-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Bianka Mussil
- Unit of Infection Models, German Primate Centre, Goettingen, Germany.
| | - Aneela Javed
- Unit of Infection Models, German Primate Centre, Goettingen, Germany. .,Department of Healthcare Biotechnology, Atta-ur-Rahman School of Applied Biosciences (ASAB), National University of Science and Technology (NUST), H12, Islamabad, Pakistan.
| | - Katharina Töpfer
- Unit of Infection Models, German Primate Centre, Goettingen, Germany.
| | - Ulrike Sauermann
- Unit of Infection Models, German Primate Centre, Goettingen, Germany.
| | - Sieghart Sopper
- Department of Hematology and Oncology, Medical University Innsbruck, ZVG 7G5 009A, Anichstr. 35, 6020, Innsbruck, Austria. .,Tyrolean Cancer Research Institute, Innsbruck, Austria.
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60
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Takeuchi JS, Ren F, Yoshikawa R, Yamada E, Nakano Y, Kobayashi T, Matsuda K, Izumi T, Misawa N, Shintaku Y, Wetzel KS, Collman RG, Tanaka H, Hirsch VM, Koyanagi Y, Sato K. Coevolutionary dynamics between tribe Cercopithecini tetherins and their lentiviruses. Sci Rep 2015; 5:16021. [PMID: 26531727 PMCID: PMC4631996 DOI: 10.1038/srep16021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 10/08/2015] [Indexed: 02/03/2023] Open
Abstract
Human immunodeficiency virus, a primate lentivirus (PLV), causes AIDS in humans, whereas most PLVs are less or not pathogenic in monkeys. These notions suggest that the co-evolutionary process of PLVs and their hosts associates with viral pathogenicity, and therefore, that elucidating the history of virus-host co-evolution is one of the most intriguing topics in the field of virology. To address this, recent studies have focused on the interplay between intrinsic anti-viral proteins, such as tetherin, and viral antagonists. Through an experimental-phylogenetic approach, here we investigate the co-evolutionary interplay between tribe Cercopithecini tetherin and viral antagonists, Nef and Vpu. We reveal that tribe Cercopithecini tetherins are positively selected, possibly triggered by ancient Nef-like factor(s). We reconstruct the ancestral sequence of tribe Cercopithecini tetherin and demonstrate that all Nef proteins are capable of antagonizing ancestral Cercopithecini tetherin. Further, we consider the significance of evolutionary arms race between tribe Cercopithecini and their PLVs.
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Affiliation(s)
- Junko S Takeuchi
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan
| | - Fengrong Ren
- Department of Bioinformatics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 1138510, Japan
| | - Rokusuke Yoshikawa
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan
| | - Eri Yamada
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan
| | - Yusuke Nakano
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.,Department of Medical Virology, Faculty of Life Sciences, Kumamoto University, Kumamoto 8608556, Japan
| | - Tomoko Kobayashi
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan
| | - Kenta Matsuda
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Taisuke Izumi
- Department of Microbiology, Institute of Health Biosciences, The University of Tokushima, Tokushima 7708503, Japan
| | - Naoko Misawa
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan
| | - Yuta Shintaku
- Wildlife Research Center, Kyoto University, Kyoto 6068203, Japan.,Japan Monkey Centre, Aichi 4840081, Japan
| | - Katherine S Wetzel
- Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Ronald G Collman
- Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Hiroshi Tanaka
- Department of Bioinformatics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 1138510, Japan
| | - Vanessa M Hirsch
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Yoshio Koyanagi
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan
| | - Kei Sato
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.,CREST, Japan Science and Technology Agency, Saitama 3220012, Japan
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Bone Marrow Stromal Antigen 2 Is a Novel Plasma Biomarker and Prognosticator for Colorectal Carcinoma: A Secretome-Based Verification Study. DISEASE MARKERS 2015; 2015:874054. [PMID: 26494939 PMCID: PMC4606116 DOI: 10.1155/2015/874054] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 06/22/2015] [Indexed: 01/21/2023]
Abstract
BACKGROUND The cancer cell secretome has been recognized as a valuable reservoir for identifying novel serum/plasma biomarkers for different cancers, including colorectal cancer (CRC). This study aimed to verify four CRC cell-secreted proteins (tumor-associated calcium signal transducer 2/trophoblast cell surface antigen 2 (TACSTD2/TROP2), tetraspanin-6 (TSPAN6), bone marrow stromal antigen 2 (BST2), and tumor necrosis factor receptor superfamily member 16 (NGFR)) as potential plasma CRC biomarkers. METHODS The study population comprises 152 CRC patients and 152 controls. Target protein levels in plasma and tissue samples were assessed by ELISA and immunohistochemistry, respectively. RESULTS Among the four candidate proteins examined by ELISA in a small sample set, only BST2 showed significantly elevated plasma levels in CRC patients versus controls. Immunohistochemical analysis revealed the overexpression of BST2 in CRC tissues, and higher BST2 expression levels correlated with poorer 5-year survival (46.47% versus 65.57%; p = 0.044). Further verification confirmed the elevated plasma BST2 levels in CRC patients (2.35 ± 0.13 ng/mL) versus controls (1.04 ± 0.03 ng/mL) (p < 0.01), with an area under the ROC curve (AUC) being 0.858 comparable to that of CEA (0.867). CONCLUSION BST2, a membrane protein selectively detected in CRC cell secretome, may be a novel plasma biomarker and prognosticator for CRC.
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Bst2/Tetherin Is Induced in Neurons by Type I Interferon and Viral Infection but Is Dispensable for Protection against Neurotropic Viral Challenge. J Virol 2015; 89:11011-8. [PMID: 26311886 DOI: 10.1128/jvi.01745-15] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 08/17/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED In permissive mouse central nervous system (CNS) neurons, measles virus (MV) spreads in the absence of hallmark viral budding or neuronal death, with transmission occurring efficiently and exclusively via the synapse. MV infection also initiates a robust type I interferon (IFN) response, resulting in the synthesis of a large number of genes, including bone marrow stromal antigen 2 (Bst2)/tetherin/CD317. Bst2 restricts the release of some enveloped viruses, but to date, its role in viral infection of neurons has not been assessed. Consequently, we investigated how Bst2 was induced and what role it played in MV neuronal infection. The magnitude of induction of neuronal Bst2 RNA and protein following IFN exposure and viral infection was notably higher than in similarly treated mouse embryo fibroblasts (MEFs). Bst2 synthesis was both IFN and Stat1 dependent. Although Bst2 prevented MV release from nonneuronal cells, its deletion had no effect on viral pathogenesis in MV-challenged mice. Our findings underscore how cell-type-specific differences impact viral infection and pathogenesis. IMPORTANCE Viral infections of the central nervous system can lead to debilitating disease and death. Moreover, it is becoming increasingly clear that nonrenewable cells, including most central nervous system neurons, combat neurotropic viral infections in fundamentally different ways than other rapidly dividing and renewable cell populations. Here we identify type I interferon signaling as a key inducer of a known antiviral protein (Bst2) in neurons. Unexpectedly, the gene is dispensable for clearance of neurotropic viral infection despite its well-defined contribution to limiting the spread of enveloped viruses in proliferating cells. A deeper appreciation of the importance of cell type heterogeneity in antiviral immunity will aid in the identification of unique therapeutic targets for life-threatening viral infections.
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Viral Membrane Channels: Role and Function in the Virus Life Cycle. Viruses 2015; 7:3261-84. [PMID: 26110585 PMCID: PMC4488738 DOI: 10.3390/v7062771] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 05/20/2015] [Accepted: 06/12/2015] [Indexed: 12/23/2022] Open
Abstract
Viroporins are small, hydrophobic trans-membrane viral proteins that oligomerize to form hydrophilic pores in the host cell membranes. These proteins are crucial for the pathogenicity and replication of viruses as they aid in various stages of the viral life cycle, from genome uncoating to viral release. In addition, the ion channel activity of viroporin causes disruption in the cellular ion homeostasis, in particular the calcium ion. Fluctuation in the calcium level triggers the activation of the host defensive programmed cell death pathways as well as the inflammasome, which in turn are being subverted for the viruses’ replication benefits. This review article summarizes recent developments in the functional investigation of viroporins from various viruses and their contributions to viral replication and virulence.
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64
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Hertoghs N, van der Aar AMG, Setiawan LC, Kootstra NA, Gringhuis SI, Geijtenbeek TBH. SAMHD1 degradation enhances active suppression of dendritic cell maturation by HIV-1. THE JOURNAL OF IMMUNOLOGY 2015; 194:4431-7. [PMID: 25825449 DOI: 10.4049/jimmunol.1403016] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/26/2015] [Indexed: 11/19/2022]
Abstract
A hallmark of HIV-1 infection is the lack of sterilizing immunity. Dendritic cells (DCs) are crucial in the induction of immunity, and lack of DC activation might underlie the absence of an effective anti-HIV-1 response. We have investigated how HIV-1 infection affects maturation of DCs. Our data show that even though DCs are productively infected by HIV-1, infection does not induce DC maturation. HIV-1 infection actively suppresses DC maturation, as HIV-1 infection inhibited TLR-induced maturation of DCs and thereby decreased the immune stimulatory capacity of DCs. Interfering with SAMHD1 restriction further increased infection of DCs, but did not lead to DC maturation. Notably, higher infection observed with SAMHD1 depletion correlated with a stronger suppression of maturation. Furthermore, blocking reverse transcription rescued TLR-induced maturation. These data strongly indicate that HIV-1 replication does not trigger immune activation in DCs, but that HIV-1 escapes immune surveillance by actively suppressing DC maturation independent of SAMHD1. Elucidation of the mechanism of suppression can lead to promising targets for therapy or vaccine design.
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Affiliation(s)
- Nina Hertoghs
- Department of Experimental Immunology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands; and
| | - Angelic M G van der Aar
- Department of Experimental Immunology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands; and
| | - Laurentia C Setiawan
- Department of Experimental Immunology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands; and Laboratory of Viral Immune Pathogenesis, Department of Experimental Immunology, Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands
| | - Neeltje A Kootstra
- Department of Experimental Immunology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands; and Laboratory of Viral Immune Pathogenesis, Department of Experimental Immunology, Center for Infection and Immunity Amsterdam, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands
| | - Sonja I Gringhuis
- Department of Experimental Immunology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands; and
| | - Teunis B H Geijtenbeek
- Department of Experimental Immunology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, the Netherlands; and
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Yamada E, Yoshikawa R, Nakano Y, Misawa N, Koyanagi Y, Sato K. Impacts of humanized mouse models on the investigation of HIV-1 infection: illuminating the roles of viral accessory proteins in vivo. Viruses 2015; 7:1373-90. [PMID: 25807049 PMCID: PMC4379576 DOI: 10.3390/v7031373] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 03/10/2015] [Accepted: 03/10/2015] [Indexed: 12/26/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) encodes four accessory genes: vif, vpu, vpr, and nef. Recent investigations using in vitro cell culture systems have shed light on the roles of these HIV-1 accessory proteins, Vif, Vpr, Vpu, and Nef, in counteracting, modulating, and evading various cellular factors that are responsible for anti-HIV-1 intrinsic immunity. However, since humans are the exclusive target for HIV-1 infection, conventional animal models are incapable of mimicking the dynamics of HIV-1 infection in vivo. Moreover, the effects of HIV-1 accessory proteins on viral infection in vivo remain unclear. To elucidate the roles of HIV-1 accessory proteins in the dynamics of viral infection in vivo, humanized mouse models, in which the mice are xenotransplanted with human hematopoietic stem cells, has been utilized. This review describes the current knowledge of the roles of HIV-1 accessory proteins in viral infection, replication, and pathogenicity in vivo, which are revealed by the studies using humanized mouse models.
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Affiliation(s)
- Eri Yamada
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.
| | - Rokusuke Yoshikawa
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.
| | - Yusuke Nakano
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.
| | - Naoko Misawa
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.
| | - Yoshio Koyanagi
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.
| | - Kei Sato
- Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto 6068507, Japan.
- CREST, Japan Science and Technology Agency, Saitama 3220012, Japan.
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Less is more: Ebola virus surface glycoprotein expression levels regulate virus production and infectivity. J Virol 2014; 89:1205-17. [PMID: 25392212 DOI: 10.1128/jvi.01810-14] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
UNLABELLED The Ebola virus (EBOV) surface glycoprotein (GP1,2) mediates host cell attachment and fusion and is the primary target for host neutralizing antibodies. Expression of GP1,2 at high levels disrupts normal cell physiology, and EBOV uses an RNA-editing mechanism to regulate expression of the GP gene. In this study, we demonstrate that high levels of GP1,2 expression impair production and release of EBOV virus-like particles (VLPs) as well as infectivity of GP1,2-pseudotyped viruses. We further show that this effect is mediated through two mechanisms. First, high levels of GP1,2 expression reduce synthesis of other proteins needed for virus assembly. Second, viruses containing high levels of GP1,2 are intrinsically less infectious, possibly due to impaired receptor binding or endosomal processing. Importantly, proteolysis can rescue the infectivity of high-GP1,2-containing viruses. Taken together, our findings indicate that GP1,2 expression levels have a profound effect on factors that contribute to virus fitness and that RNA editing may be an important mechanism employed by EBOV to regulate GP1,2 expression in order to optimize virus production and infectivity. IMPORTANCE The Ebola virus (EBOV), as well as other members of the Filoviridae family, causes severe hemorrhagic fever that is highly lethal, with up to 90% mortality. The EBOV surface glycoprotein (GP1,2) plays important roles in virus infection and pathogenesis, and its expression is tightly regulated by an RNA-editing mechanism during virus replication. Our study demonstrates that the level of GP1,2 expression profoundly affects virus particle production and release and uncovers a new mechanism by which Ebola virus infectivity is regulated by the level of GP1,2 expression. These findings extend our understanding of EBOV infection and replication in adaptation of host environments, which will aid the development of countermeasures against EBOV infection.
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Wang X, Li C, Zhou L, Zhang N, Wang X, Ge X, Guo X, Yang H. Porcine reproductive and respiratory syndrome virus counteracts the porcine intrinsic virus restriction factors-IFITM1 and Tetherin in MARC-145 cells. Virus Res 2014; 191:92-100. [PMID: 25102331 DOI: 10.1016/j.virusres.2014.07.025] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 07/22/2014] [Accepted: 07/25/2014] [Indexed: 12/12/2022]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) has been recognized to modulate the innate immune response of host. However, little is known about the effects of PRRSV infection on porcine intrinsic virus-restriction factors. This study presents the first demonstration that the nonstructural protein 3 (Nsp3) or envelope (E) protein of PRRSV interacted with porcine intrinsic virus-restriction factor IFITM1 or Tetherin. Next, in PRRSV-infected MARC-145 cells and the transfected cells with the IFITM1- or Tetherin-expressing plasmid, IFITM1 was shown to be mainly distributed perinuclear, and Tetherin was proposed to be partially removed away from cell surface. Moreover, the overexpression of IFITM1 and Tetherin were shown to have no obvious effects on the replication of PRRSV in MARC-145 cells. The Nsp3 of PRRSV was demonstrated to induce the proteasome-dependent degradation of IFITM1 upon PRRSV infection. These findings suggest that PRRSV might counteract the antiviral functions of IFITM1 and Tetherin by the interaction of the Nsp3 with IFITM1 and the E protein with Tetherin, providing a novel clue for exploring possible mechanisms associated with the evasion of PRRSV from immune recognition of host.
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Affiliation(s)
- Xiaolong Wang
- Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China
| | - Congcong Li
- Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China
| | - Lei Zhou
- Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China
| | - Ning Zhang
- Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China
| | - Xingchen Wang
- Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China
| | - Xinna Ge
- Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China
| | - Xin Guo
- Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China
| | - Hanchun Yang
- Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China.
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Targeted therapy for HM1.24 (CD317) on multiple myeloma cells. BIOMED RESEARCH INTERNATIONAL 2014; 2014:965384. [PMID: 25143955 PMCID: PMC4124849 DOI: 10.1155/2014/965384] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 07/02/2014] [Indexed: 11/18/2022]
Abstract
Multiple myeloma (MM) still remains an incurable disease, at least because of the existence of cell-adhesion mediated drug-resistant MM cells and/or continuous recruitment of presumed MM cancer stem cell-like cells (CSCs). As a new alternative treatment modality, immunological approaches using monoclonal antibodies (mAbs) and/or cytotoxic T lymphocytes (CTLs) are now attracting much attention as a novel strategy attacking MM cells. We have identified that HM1.24 [also known as bone marrow stromal cell antigen 2 (BST2) or CD317] is overexpressed on not only mature MM cells but also MM CSCs. We then have developed a humanized mAb to HM1.24 and defucosylated version of the mAb to adapt to clinical practice. Moreover, we have successfully induced HM1.24-specific CTLs against MM cells. The combination of these innovative therapeutic modalities may likely exert an anti-MM activity by evading the drug resistance mechanism and eliminating presumed CSCs in MM.
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69
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Characterization of red-capped mangabey tetherin: implication for the co-evolution of primates and their lentiviruses. Sci Rep 2014; 4:5529. [PMID: 24984862 PMCID: PMC4078312 DOI: 10.1038/srep05529] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 06/11/2014] [Indexed: 11/11/2022] Open
Abstract
Primate lentiviruses including human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency viruses (SIVs) evolved through the acquisition of antagonists against intrinsic host restriction factors, such as tetherin. It is widely accepted that HIV-1 has emerged by zoonotic transmission of SIV in chimpanzee (SIVcpz), and that SIVcpz Nef protein antagonizes chimpanzee tetherin. Although Nef of SIVcpz shares a common ancestor with that of SIVrcm, an SIV in red-capped mangabey (Cercocebus torquatus), it remains unclear whether SIVrcm Nef can antagonize tetherin of its natural host. In this study, we determine the sequence of red-capped mangabey tetherin for the first time and directly demonstrate that SIVrcm Nef is the bona fide antagonist of red-capped mangabey tetherin. These findings suggest that SIVrcm Nef is the functional ancestor of SIVcpz Nef. Moreover, molecular phylogenetic analyses reveal that tetherins of the genus Cercocebus have experienced adaptive evolution, which is presumably promoted by primate lentiviruses.
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70
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Maturation and vesicle-mediated egress of primate gammaherpesvirus rhesus monkey rhadinovirus require inner tegument protein ORF52. J Virol 2014; 88:9111-28. [PMID: 24899183 DOI: 10.1128/jvi.01502-14] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
UNLABELLED The tegument layer of herpesviruses comprises a collection of proteins that is unique to each viral species. In rhesus monkey rhadinovirus (RRV), a close relative of the human oncogenic pathogen Kaposi's sarcoma-associated herpesvirus, ORF52 is a highly abundant tegument protein tightly associated with the capsid. We now report that ORF52 knockdown during RRV infection of rhesus fibroblasts led to a greater than 300-fold reduction in the viral titer by 48 h but had little effect on the number of released particles and caused only modest reductions in the levels of intracellular viral genomic DNA and no appreciable change in viral DNA packaging into capsids. These data suggested that the lack of ORF52 resulted in the production and release of defective particles. In support of this interpretation, transmission electron microscopy (TEM) revealed that without ORF52, capsid-like particles accumulated in the cytoplasm and were unable to enter egress vesicles, where final tegumentation and envelopment normally occur. TEM also demonstrated defective particles in the medium that closely resembled the accumulating intracellular particles, having neither a full tegument nor an envelope. The disruption in tegument formation from ORF52 suppression, therefore, prevented the incorporation of ORF45, restricting its subcellular localization to the nucleus and appearing, by confocal microscopy, to inhibit particle transport toward the periphery. Ectopic expression of small interfering RNA (siRNA)-resistant ORF52 was able to partially rescue all of these phenotypic changes. In sum, our results indicate that efficient egress of maturing virions and, in agreement with studies on murine gammaherpesvirus 68 (MHV-68), complete tegumentation and secondary envelopment are dependent on intact ORF52. IMPORTANCE The tegument, or middle layer, of herpesviruses comprises both viral and cellular proteins that play key roles in the viral life cycle. A subset of these proteins is present only within members of one of the three subfamilies (alphaherpesviruses, betaherpesviruses, or gammaherpesviruses) of Herpesviridae. In this report, we show that the gammaherpesvirus-specific tegument protein ORF52 is critical for maturation of RRV, the closest relative of Kaposi's sarcoma-associated herpesvirus (KSHV) (a human cancer-causing pathogen) that has undergone this type of analysis. Without ORF52, the nascent subviral particles are essentially stuck in maturation limbo, unable to acquire the tegument or outer (envelope) layers. This greatly attenuates infectivity. Our data, together with earlier work on a murine homolog, as well as a more distantly related human homolog, provide a more complete understanding of how early protein interactions involving virus-encoded tegument proteins are critical for virus assembly and are also, therefore, potentially attractive therapeutic targets.
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71
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Nityanandam R, Serra-Moreno R. BCA2/Rabring7 targets HIV-1 Gag for lysosomal degradation in a tetherin-independent manner. PLoS Pathog 2014; 10:e1004151. [PMID: 24852021 PMCID: PMC4031200 DOI: 10.1371/journal.ppat.1004151] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Accepted: 04/14/2014] [Indexed: 12/04/2022] Open
Abstract
BCA2 (Rabring7, RNF115 or ZNF364) is a RING-finger E3 ubiquitin ligase that was identified as a co-factor in the restriction imposed by tetherin/BST2 on HIV-1. Contrary to the current model, in which BCA2 lacks antiviral activity in the absence of tetherin, we found that BCA2 possesses tetherin-independent antiviral activity. Here we show that the N-terminus of BCA2 physically interacts with the Matrix region of HIV-1 and other retroviral Gag proteins and promotes their ubiquitination, redistribution to endo-lysosomal compartments and, ultimately, lysosomal degradation. The targeted depletion of BCA2 in tetherin-expressing and tetherin-deficient cells results in a significant increase in virus release and replication, indicating that endogenous BCA2 possesses antiviral activity. Therefore, these results indicate that BCA2 functions as an antiviral factor that targets HIV-1 Gag for degradation, impairing virus assembly and release. Tetherin (also known as BST2, CD317 or HM1.24) is an interferon-inducible cellular factor that interferes with the release of enveloped viruses from infected cells. A recent study identified BCA2 (Breast Cancer-Associated gene 2, also known as RNF115, ZNF364 or Rabring7), a RING-finger E3 ubiquitin ligase, as a co-factor in the tetherin-mediated restriction of HIV-1. According to this model, BCA2 interacts with sequences in the N-terminus of tetherin to promote the internalization and lysosomal degradation of tethered HIV-1 particles, with no apparent antiviral activity in cells not expressing tetherin. However, here we show for the first time that BCA2 inhibits virus production for HIV-1 and other retroviruses in a tetherin-independent manner by reducing the cellular levels of Gag – the precursor of the structural proteins Matrix, Capsid, Nucleocapsid and p6. Hence, contrary to its reported role as a tetherin co-factor, BCA2 functions as a tetherin-independent antiviral factor that impairs virus assembly and release.
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Affiliation(s)
- Ramya Nityanandam
- Division of Immunology, New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts, United States of America
| | - Ruth Serra-Moreno
- Division of Immunology, New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts, United States of America
- * E-mail:
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Arias JF, Heyer LN, von Bredow B, Weisgrau KL, Moldt B, Burton DR, Rakasz EG, Evans DT. Tetherin antagonism by Vpu protects HIV-infected cells from antibody-dependent cell-mediated cytotoxicity. Proc Natl Acad Sci U S A 2014; 111:6425-30. [PMID: 24733916 PMCID: PMC4035966 DOI: 10.1073/pnas.1321507111] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tetherin is an IFN-inducible transmembrane protein that inhibits the detachment of enveloped viruses from infected cells. HIV-1 overcomes this restriction factor by expressing HIV-1 viral protein U (Vpu), which down-regulates and degrades tetherin. We report that mutations in Vpu that impair tetherin antagonism increase the susceptibility of HIV-infected cells to antibody-dependent cell-mediated cytotoxicity (ADCC), and conversely that RNAi knockdown of tetherin, but not other cellular proteins down-modulated by Vpu, decreases the susceptibility of HIV-infected cells to ADCC. These results reveal that Vpu protects HIV-infected cells from ADCC as a function of its ability to counteract tetherin. By serving as link between innate and adaptive immunity, the antiviral activity of tetherin may be augmented by virus-specific antibodies, and hence much greater than previously appreciated.
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Affiliation(s)
- Juan F. Arias
- Department of Microbiology and Immunobiology, New England Primate Research Center, Harvard Medical School, Southborough, MA 01772
| | - Lisa N. Heyer
- Department of Microbiology and Immunobiology, New England Primate Research Center, Harvard Medical School, Southborough, MA 01772
| | - Benjamin von Bredow
- Department of Microbiology and Immunobiology, New England Primate Research Center, Harvard Medical School, Southborough, MA 01772
| | - Kim L. Weisgrau
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53715
| | - Brian Moldt
- Department of Immunology and Microbial Science, International AIDS Vaccine Initiative Neutralizing Antibody Center and Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, CA 92037; and
| | - Dennis R. Burton
- Department of Immunology and Microbial Science, International AIDS Vaccine Initiative Neutralizing Antibody Center and Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, CA 92037; and
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA 02139
| | - Eva G. Rakasz
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53715
| | - David T. Evans
- Department of Microbiology and Immunobiology, New England Primate Research Center, Harvard Medical School, Southborough, MA 01772
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Jia X, Weber E, Tokarev A, Lewinski M, Rizk M, Suarez M, Guatelli J, Xiong Y. Structural basis of HIV-1 Vpu-mediated BST2 antagonism via hijacking of the clathrin adaptor protein complex 1. eLife 2014; 3:e02362. [PMID: 24843023 PMCID: PMC4018625 DOI: 10.7554/elife.02362] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
BST2/tetherin, an antiviral restriction factor, inhibits the release of enveloped viruses from the cell surface. Human immunodeficiency virus-1 (HIV-1) antagonizes BST2 through viral protein u (Vpu), which downregulates BST2 from the cell surface. We report the crystal structure of a protein complex containing Vpu and BST2 cytoplasmic domains and the core of the clathrin adaptor protein complex 1 (AP1). This, together with our biochemical and functional validations, reveals how Vpu hijacks the AP1-dependent membrane trafficking pathways to mistraffick BST2. Vpu mimics a canonical acidic dileucine-sorting motif to bind AP1 in the cytosol, while simultaneously interacting with BST2 in the membrane. These interactions enable Vpu to build on an intrinsic interaction between BST2 and AP1, presumably causing the observed retention of BST2 in juxtanuclear endosomes and stimulating its degradation in lysosomes. The ability of Vpu to hijack AP-dependent trafficking pathways suggests a potential common theme for Vpu-mediated downregulation of host proteins. DOI:http://dx.doi.org/10.7554/eLife.02362.001 HIV is a retrovirus that attacks the immune system, making the body increasingly susceptible to opportunistic infections and disease and eventually leading to AIDS. While antiretroviral drugs have allowed people with AIDS to live longer, there is no cure or vaccine for HIV. Two types of HIV exist, with HIV-1 being much more common and pathogenic than HIV-2. Like other ‘complex’ retroviruses, the HIV-1 genome contains genes that encode various proteins that allow the virus to disrupt the immune response of the host it is attacking. Viral protein u is a protein encoded by HIV-1 (but not HIV-2) that counteracts an antiviral protein called BST2 in the host. BST2, which is part of the host's innate immune response, prevents newly formed viruses from leaving the surface of infected cells. By counteracting BST2, viral protein u allows the virus to spread in the host more efficiently. Like many proteins, newly produced BST2 is packaged inside structures called vesicles in a part of the cell called the trans-Golgi network, and then sent to its destination. Complexes formed by various proteins make sure that the vesicles take their cargo to their correct destinations within the cell. Two adaptor protein complexes—known as AP1 and AP2—are thought to be involved the transport of BST2. However, it is not known how viral protein u stops BST2 from reaching the cell surface, or how it decreases the amount of BST2 in the cell as a whole. Jia et al. show how viral protein u and BST2 jointly interact with AP1. This interaction leads to the mistrafficking and degradation of BST2 and the counteraction of its antiviral activity. DOI:http://dx.doi.org/10.7554/eLife.02362.002
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Affiliation(s)
- Xiaofei Jia
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
| | - Erin Weber
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
| | - Andrey Tokarev
- Department of Medicine, University of California San Diego, La Jolla, United States The VA San Diego Healthcare System, San Diego, United States
| | - Mary Lewinski
- Department of Medicine, University of California San Diego, La Jolla, United States The VA San Diego Healthcare System, San Diego, United States
| | - Maryan Rizk
- Department of Medicine, University of California San Diego, La Jolla, United States The VA San Diego Healthcare System, San Diego, United States
| | - Marissa Suarez
- Department of Medicine, University of California San Diego, La Jolla, United States The VA San Diego Healthcare System, San Diego, United States
| | - John Guatelli
- Department of Medicine, University of California San Diego, La Jolla, United States The VA San Diego Healthcare System, San Diego, United States
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States
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Herbert C, Shadie AM, Bunting MM, Tedla N, Garthwaite L, Freeman A, Yoo H, Park SH, Kumar RK. Anti-inflammatory and anti-remodelling effects of ISU201, a modified form of the extracellular domain of human BST2, in experimental models of asthma: association with inhibition of histone acetylation. PLoS One 2014; 9:e90436. [PMID: 24594933 PMCID: PMC3940910 DOI: 10.1371/journal.pone.0090436] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Accepted: 01/31/2014] [Indexed: 11/19/2022] Open
Abstract
There are few alternatives to glucocorticosteroids for treatment of asthma. We assessed the activity of a novel protein drug designated ISU201, the extracellular domain of the human cell surface protein BST2, stabilised by fusion with the Fc region of IgG, in mouse models of mild chronic asthma and an acute exacerbation of asthma. The ability of ISU201 to suppress airway inflammation and remodelling was compared with that of dexamethasone. Female BALB/c mice were systemically sensitised with ovalbumin, then received controlled low-level challenge with aerosolised ovalbumin for 6 weeks, which induced lesions of mild chronic asthma, and were treated with drugs during the final 2 weeks. Alternatively, sensitised mice received 4 weeks of chronic low-level challenge and were treated 24 and 2 hours before a final single moderate-level challenge, which triggered acute airway inflammation simulating an asthmatic exacerbation. Inflammation and remodelling were quantified, as was the expression of pro-inflammatory cytokines in bronchoalveolar lavage fluid and tissues. To identify cellular targets of ISU201, we assessed the effects of the drug on activated lymphocytes, macrophages and airway epithelial cells. In the model of mild chronic asthma, ISU201 was as effective as dexamethasone in suppressing airway inflammation and most changes of remodelling. In the model of an allergen-induced acute exacerbation of chronic asthma, ISU201 was also an effective anti-inflammatory agent, although it was less active than dexamethasone. The drug acted on multiple cellular targets, suppressing production of pro-inflammatory cytokines by lymphocytes and macrophages. ISU201 significantly reduced acetylation of histone H4 in airway epithelial cells, suggesting at least one potential mechanism of action. We conclude that in these models of asthma, ISU201 is a broad-spectrum inhibitor of both airway inflammation and remodelling. Thus, unlike drugs which target specific mediators, it could potentially be an alternative or an adjunct to glucocorticoids for the treatment of asthma.
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Affiliation(s)
- Cristan Herbert
- Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Alexander M. Shadie
- Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Melissa M. Bunting
- Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Nicodemus Tedla
- Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Linda Garthwaite
- Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Araluen Freeman
- Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | | | | | - Rakesh K. Kumar
- Inflammation and Infection Research Centre, School of Medical Sciences, University of New South Wales, Sydney, Australia
- * E-mail:
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Activities of transmitted/founder and chronic clade B HIV-1 Vpu and a C-terminal polymorphism specifically affecting virion release. J Virol 2014; 88:5062-78. [PMID: 24574397 DOI: 10.1128/jvi.03472-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
UNLABELLED Acute HIV-1 infection is characterized by a type I interferon response, resulting in the induction of host restriction factors. HIV-1 has evolved to counteract these factors, and one such adaptation, the ability of Vpu to counteract BST2/tetherin, is associated with the evolution of simian immunodeficiency virus (SIVcpz) into pandemic group M human immunodeficiency virus type 1 (HIV-1). During transmission between individuals, very few viruses or even a single virus, the "transmitted/founder" (T/F) virus, gives rise to the new infection, but in the new host the selective pressure of the immune response yields the diverse "quasispecies" of chronic infection. Here we examine the functional characteristics of Vpu proteins encoded by T/F viruses compared to acute and chronic viruses from longitudinally sampled subjects. The studied T/F Vpu proteins showed a trend toward optimized CD4 downregulation compared to chronic Vpu proteins but did not differ substantially in their ability to downregulate BST2 or enhance virion release, although individual clones from each group were impaired in these activities. Analysis of the functionally impaired clones identified a C-terminal residue, W76, as important specifically for Vpu enhancement of virion release. Primary Vpu clones encoding a W76G polymorphism, or site-directed mutants encoding a W76G substitution, were impaired in their ability to enhance virion release, but they were not defective for BST2 surface downregulation. Conversely, the virion release function of impaired primary clones was restored by creating a G76W substitution. The identification of W76 as important for virion release enhancement that is independent of BST2 surface downregulation supports the potential to mechanistically separate these functions of Vpu. IMPORTANCE To establish infection in a host, HIV-1 must evade the host's immune response, including the production of antiviral factors. HIV-1 encodes proteins that antagonize these defenses, including Vpu. Vpu counteracts the host protein BST2, which blocks the release of progeny viruses from the host cell. To determine the importance of Vpu activity to HIV-1 transmission, this study assessed the functionality of Vpu from viruses isolated soon after transmission ("transmitted/founder" viruses) compared to isolates from chronic infection. Although the anti-BST2 activity of Vpu proteins from the tested transmitted/founder viruses did not differ from the activity of the chronic Vpu proteins, the transmitted/founder Vpu proteins trended toward having superior activity against another host protein, CD4. Further, this study identified an amino acid near the C terminus of Vpu that is specifically important for Vpu's ability to enhance the release of progeny virus from the host cell, supporting the notion of a new mechanism for this function of Vpu.
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Feline immunodeficiency virus envelope glycoproteins antagonize tetherin through a distinctive mechanism that requires virion incorporation. J Virol 2014; 88:3255-72. [PMID: 24390322 DOI: 10.1128/jvi.03814-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED BST2/tetherin inhibits the release of enveloped viruses from cells. Primate lentiviruses have evolved specific antagonists (Vpu, Nef, and Env). Here we characterized tetherin proteins of species representing both branches of the order Carnivora. Comparison of tiger and cat (Feliformia) to dog and ferret (Caniformia) genes demonstrated that the tiger and cat share a start codon mutation that truncated most of the tetherin cytoplasmic tail early in the Feliformia lineage (19 of 27 amino acids, including the dual tyrosine motif). Alpha interferon (IFN-α) induced tetherin and blocked feline immunodeficiency virus (FIV) replication in lymphoid and nonlymphoid feline cells. Budding of bald FIV and HIV particles was blocked by carnivore tetherins. However, infectious FIV particles were resistant, and spreading FIV replication was uninhibited. Antagonism mapped to the envelope glycoprotein (Env), which rescued FIV from carnivore tetherin restriction when expressed in trans but, in contrast to known antagonists, did not rescue noncognate particles. Also unlike the primate lentiviral antagonists, but similar to the Ebola virus glycoprotein, FIV Env did not reduce intracellular or cell surface tetherin levels. Furthermore, FIV-enveloped FIV particles actually required tetherin for optimal release from cells. The results show that FIV Envs mediate a distinctive tetherin evasion. Well adapted to a phylogenetically ancient tetherin tail truncation in the Felidae, it requires functional virion incorporation of Env, and it shields the budding particle without downregulating plasma membrane tetherin. Moreover, FIV has evolved dependence on this protein: particles containing FIV Env need tetherin for optimal release from the cell, while Env(-) particles do not. IMPORTANCE HIV-1 antagonizes the restriction factor tetherin with the accessory protein Vpu, while HIV-2 and the filovirus Ebola use their envelope (Env) glycoproteins for this purpose. It turns out that the FIV tetherin antagonist is also its Env protein, but the mechanism is distinctive. Unlike other tetherin antagonists, FIV Env cannot act in trans to rescue vpu-deficient HIV-1. It must be incorporated specifically into FIV virions to be active. Also unlike other retroviral antagonists, but similar to Ebola virus Env, it does not act by downregulating or degrading tetherin. FIV Env might exclude tetherin locally or direct assembly to tetherin-negative membrane domains. Other distinctive features are apparent, including evidence that this virus evolved an equilibrium in which tetherin is both restriction factor and cofactor, as FIV requires tetherin for optimal particle release.
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Rahmberg AR, Neidermyer WJ, Breed MW, Alvarez X, Midkiff CC, Piatak M, Lifson JD, Evans DT. Tetherin upregulation in simian immunodeficiency virus-infected macaques. J Virol 2013; 87:13917-21. [PMID: 24109219 PMCID: PMC3838227 DOI: 10.1128/jvi.01757-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 10/02/2013] [Indexed: 11/20/2022] Open
Abstract
Here we show that simian immunodeficiency virus (SIV) infection of rhesus macaques results in rapid upregulation of tetherin (BST-2 or CD317) on peripheral blood lymphocytes, including the CD4(+) CCR5(+) T cell targets of virus infection, with a peak of induction that coincides with peak alpha interferon (IFN-α) levels in plasma, and that tetherin remains above baseline levels throughout chronic infection. These observations are consistent with a role for tetherin in innate immunity to immunodeficiency virus infection.
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Affiliation(s)
- Andrew R. Rahmberg
- Department of Microbiology and Immunobiology, Harvard Medical School, New England Primate Research Center, Southborough, Massachusetts, USA
| | - William J. Neidermyer
- Department of Microbiology and Immunobiology, Harvard Medical School, New England Primate Research Center, Southborough, Massachusetts, USA
| | - Matthew W. Breed
- Division of Comparative Pathology, Tulane National Primate Research Center, Covington, Louisiana, USA
| | - Xavier Alvarez
- Division of Comparative Pathology, Tulane National Primate Research Center, Covington, Louisiana, USA
| | - Cecily C. Midkiff
- Division of Comparative Pathology, Tulane National Primate Research Center, Covington, Louisiana, USA
| | - Michael Piatak
- SAIC—Frederick, National Cancer Institute at Frederick, Frederick, Maryland, USA
| | - Jeffrey D. Lifson
- SAIC—Frederick, National Cancer Institute at Frederick, Frederick, Maryland, USA
| | - David T. Evans
- Department of Microbiology and Immunobiology, Harvard Medical School, New England Primate Research Center, Southborough, Massachusetts, USA
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Emerging Role of the Host Restriction Factor Tetherin in Viral Immune Sensing. J Mol Biol 2013; 425:4956-64. [DOI: 10.1016/j.jmb.2013.09.029] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/20/2013] [Accepted: 09/22/2013] [Indexed: 12/22/2022]
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Equine tetherin blocks retrovirus release and its activity is antagonized by equine infectious anemia virus envelope protein. J Virol 2013; 88:1259-70. [PMID: 24227834 DOI: 10.1128/jvi.03148-13] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Human tetherin is a host restriction factor that inhibits replication of enveloped viruses by blocking viral release. Tetherin has an unusual topology that includes an N-terminal cytoplasmic tail, a single transmembrane domain, an extracellular domain, and a C-terminal glycosylphosphatidylinositol anchor. Tetherin is not well conserved across species, so it inhibits viral replication in a species-specific manner. Thus, studies of tetherin activities from different species provide an important tool for understanding its antiviral mechanism. Here, we report cloning of equine tetherin and characterization of its antiviral activity. Equine tetherin shares 53%, 40%, 36%, and 34% amino acid sequence identity with feline, human, simian, and murine tetherins, respectively. Like the feline tetherin, equine tetherin has a shorter N-terminal domain than human tetherin. Equine tetherin is localized on the cell surface and strongly blocks human immunodeficiency virus type 1 (HIV-1), simian immunodeficiency virus (SIV), and equine infectious anemia virus (EIAV) release from virus-producing cells. The antiviral activity of equine tetherin is neutralized by EIAV envelope protein, but not by the HIV-1 accessory protein Vpu, which is a human tetherin antagonist, and EIAV envelope protein does not counteract human tetherin. These results shed new light on our understanding of the species-specific tetherin antiviral mechanism.
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80
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Perrotti E, Marsili G, Sgarbanti M, Remoli AL, Fragale A, Acchioni C, Orsatti R, Battistini A. IRF-7: an antiviral factor and beyond. Future Virol 2013. [DOI: 10.2217/fvl.13.88] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
This review will summarize main characteristics and functions of IRF-7. IRF-7 and the highly homologous IRF-3 are two members of the IRF family of transcription factors that have emerged as crucial regulators of type I interferon (IFN) in response to pathogenic infections downstream pathogen recognition receptors. IRF-7 is also part of a positive-feedback regulatory loop essential for sustained IFN responses. Thus, tight regulation of its expression and activity is necessary to balance IFN-mediated beneficial effects and unwanted pathological consequences of IFN overproduction. Its role as an antiviral factor independent of IFN expression, and its involvement in other cellular functions beyond antiviral functions, including regulation of oncogenesis and metabolism, underscore its important role in the regulation of cellular homeostasis.
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Affiliation(s)
- Edvige Perrotti
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Giulia Marsili
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Marco Sgarbanti
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Anna Lisa Remoli
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Alessandra Fragale
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Chiara Acchioni
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Roberto Orsatti
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
| | - Angela Battistini
- Department of Infectious, Parasitic & Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 299, 00161 Rome, Italy
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81
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Viral channel proteins in intracellular protein-protein communication: Vpu of HIV-1, E5 of HPV16 and p7 of HCV. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:1113-21. [PMID: 24035804 DOI: 10.1016/j.bbamem.2013.08.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 08/06/2013] [Accepted: 08/09/2013] [Indexed: 01/20/2023]
Abstract
Viral channel forming proteins are known for their capability to make the lipid membrane of the host cell and its subcellular compartments permeable to ions and small compounds. There is increasing evidence that some of the representatives of this class of proteins are also strongly interacting with host proteins and the effectiveness of this interaction seems to be high. Interaction of viral channel proteins with host factors has been proposed by bioinformatics approaches and has also been identified experimentally. An overview of the interactions with host proteins is given for Vpu from HIV-1, E5 from HPV-16 and p7 from HCV. This article is part of a Special Issue entitled: Viral Membrane Proteins - Channels for Cellular Networking.
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Rodriguez Rodrigues C, Remes Lenicov F, Jancic C, Sabatté J, Cabrini M, Ceballos A, Merlotti A, Gonzalez H, Ostrowski M, Geffner J. Candida albicans delays HIV-1 replication in macrophages. PLoS One 2013; 8:e72814. [PMID: 24009706 PMCID: PMC3751824 DOI: 10.1371/journal.pone.0072814] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2013] [Accepted: 07/21/2013] [Indexed: 11/19/2022] Open
Abstract
Macrophages are one of the most important HIV-1 target cells. Unlike CD4(+) T cells, macrophages are resistant to the cytophatic effect of HIV-1. They are able to produce and harbor the virus for long periods acting as a viral reservoir. Candida albicans (CA) is a commensal fungus that colonizes the portals of HIV-1 entry, such as the vagina and the rectum, and becomes an aggressive pathogen in AIDS patients. In this study, we analyzed the ability of CA to modulate the course of HIV-1 infection in human monocyte-derived macrophages. We found that CA abrogated HIV-1 replication in macrophages when it was evaluated 7 days after virus inoculation. A similar inhibitory effect was observed in monocyte-derived dendritic cells. The analysis of the mechanisms responsible for the inhibition of HIV-1 production in macrophages revealed that CA efficiently sequesters HIV-1 particles avoiding its infectivity. Moreover, by acting on macrophages themselves, CA diminishes their permissibility to HIV-1 infection by reducing the expression of CD4, enhancing the production of the CCR5-interacting chemokines CCL3/MIP-1α, CCL4/MIP-1β, and CCL5/RANTES, and stimulating the production of interferon-α and the restriction factors APOBEC3G, APOBEC3F, and tetherin. Interestingly, abrogation of HIV-1 replication was overcome when the infection of macrophages was evaluated 2-3 weeks after virus inoculation. However, this reactivation of HIV-1 infection could be silenced by CA when added periodically to HIV-1-challenged macrophages. The induction of a silent HIV-1 infection in macrophages at the periphery, where cells are continuously confronted with CA, might help HIV-1 to evade the immune response and to promote resistance to antiretroviral therapy.
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Affiliation(s)
- Christian Rodriguez Rodrigues
- Instituto de Investigaciones Médicas en Retrovirus y SIDA (INBIRS), Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Federico Remes Lenicov
- Instituto de Investigaciones Médicas en Retrovirus y SIDA (INBIRS), Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Carolina Jancic
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), Hospital de Clínicas “José de San Martín”, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Juan Sabatté
- Instituto de Investigaciones Médicas en Retrovirus y SIDA (INBIRS), Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Mercedes Cabrini
- Instituto de Investigaciones Médicas en Retrovirus y SIDA (INBIRS), Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Ana Ceballos
- Instituto de Investigaciones Médicas en Retrovirus y SIDA (INBIRS), Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Antonela Merlotti
- Instituto de Investigaciones Médicas en Retrovirus y SIDA (INBIRS), Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Heidi Gonzalez
- Instituto de Investigaciones Médicas en Retrovirus y SIDA (INBIRS), Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Matías Ostrowski
- Instituto de Investigaciones Médicas en Retrovirus y SIDA (INBIRS), Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
| | - Jorge Geffner
- Instituto de Investigaciones Médicas en Retrovirus y SIDA (INBIRS), Facultad de Medicina, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), Hospital de Clínicas “José de San Martín”, Universidad de Buenos Aires, Ciudad de Buenos Aires, Argentina
- * E-mail:
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83
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Müller B, Heilemann M. Shedding new light on viruses: super-resolution microscopy for studying human immunodeficiency virus. Trends Microbiol 2013; 21:522-33. [PMID: 23916730 DOI: 10.1016/j.tim.2013.06.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 06/20/2013] [Accepted: 06/27/2013] [Indexed: 01/09/2023]
Abstract
For more than 70 years electron microscopy (EM) techniques have played an important role in investigating structures of enveloped viruses. By contrast, use of fluorescence microscopy (FM) methods for this purpose was limited by the fact that the size of virus particles is generally around or below the diffraction limit of light microscopy. Various super-resolution (SR) fluorescence imaging techniques developed over the past two decades bypass the diffraction limit of light microscopy, allowing visualization of subviral details and bridging the gap between conventional FM and EM methods. We summarize here findings on human immunodeficiency virus (HIV-1) obtained using SR-FM techniques. Although the number of published studies is currently limited and some of the pioneering analyses also covered methodological or descriptive aspects, recent publications clearly indicate the potential to approach open questions in HIV-1 replication from a new angle.
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Affiliation(s)
- Barbara Müller
- Department of Infectious Diseases, Virology, University of Heidelberg, Germany.
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84
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Chung J, DiGiusto DL, Rossi JJ. Combinatorial RNA-based gene therapy for the treatment of HIV/AIDS. Expert Opin Biol Ther 2013; 13:437-45. [PMID: 23394377 DOI: 10.1517/14712598.2013.761968] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
INTRODUCTION HIV/AIDS continues to be a worldwide health problem and viral eradication has been an elusive goal. HIV+ patients are currently treated with combination antiretroviral therapy (cART) which is not curative. For many patients, cART is inaccessible, intolerable or unaffordable. Therefore, a new class of therapeutics for HIV is required to overcome these limitations. Cell and gene therapy for HIV has been proposed as a way to provide a functional cure for HIV in the form of a virus/infection resistant immune system. AREAS COVERED In this review, the authors describe the standard therapy for HIV/AIDS, its limitations, current areas of investigation and the potential of hematopoietic stem cells modified with anti-HIV RNAs as a means to affect a functional cure for HIV. EXPERT OPINION Cell and gene therapy for HIV/AIDS is a promising alternative to antiviral drug therapy and may provide a functional cure. In order to show clinical benefit, multiple mechanisms of inhibition of HIV entry and lifecycle are likely to be required. Among the most promising antiviral strategies is the use of transgenic RNA molecules that provide protection from HIV infection. When these molecules are delivered as gene-modified hematopoietic stem and progenitor cells, long-term repopulation of the patient's immune system with gene-modified progeny has been observed.
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Affiliation(s)
- Janet Chung
- Beckman Research Institute of City of Hope, Department of Molecular and Cell Biology, 1500 East Duarte Road, CA 91010, USA
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85
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Abstract
Tetherin, an interferon-inducible membrane protein, inhibits the release of nascent enveloped viral particles from the surface of infected cells. However, the mechanisms underlying virion retention have not yet been fully delineated. Here, we employ biochemical assays and engineered tetherin proteins to demonstrate conclusively that virion tethers are composed of the tetherin protein itself, and to elucidate the configuration and topology that tetherin adopts during virion entrapment. We demonstrate that tetherin dimers adopt an “axial” configuration, in which pairs of transmembrane domains or pairs of glycosylphosphatidyl inositol anchors are inserted into assembling virion particles, while the remaining pair of membrane anchors remains embedded in the infected cell membrane. We use quantitative western blotting to determine that a few dozen tetherin dimers are used to tether each virion particle, and that there is ∼3- to 5-fold preference for the insertion of glycosylphosphatidyl inositol anchors rather than transmembrane domains into tethered virions. Cumulatively, these results demonstrate that axially configured tetherin homodimers are directly responsible for trapping virions at the cell surface. We suggest that insertion of glycosylphosphatidyl inositol anchors may be preferred so that effector functions that require exposure of the tetherin N-terminus to the cytoplasm of infected cells are retained. The cellular restriction factor, tetherin, prevents HIV-1 and other enveloped virus particles from being disseminated into the extracellular milieu by infiltrating their envelopes and by physically crosslinking them to the cell surface. It is known that tetherin consists of pairs of membrane anchors, situated at either end of a rod-shaped molecule, but how tetherin causes virion tethering has been difficult to unambiguously determine. In this work, we develop genetic and biochemical approaches to probe tetherin molecules that have infiltrated tethered virions. We show that tetherin adopts an “axial” configuration in its functional state, with a pair of membrane anchors situated at one end of the rod-like structure inserted into a tethered virion. While either end of the rod can be inserted into a virion, there is a preference for the insertion of its lipid (glycosylphosphatidyl inositol) modified carboxyl-terminus into virion envelopes. These studies demonstrate unequivocally that the tetherin molecule itself is directly responsible for trapping virions, and dissect the molecular mechanism underpinning its antiviral activity.
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86
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Serra-Moreno R, Zimmermann K, Stern LJ, Evans DT. Tetherin/BST-2 antagonism by Nef depends on a direct physical interaction between Nef and tetherin, and on clathrin-mediated endocytosis. PLoS Pathog 2013; 9:e1003487. [PMID: 23853598 PMCID: PMC3708871 DOI: 10.1371/journal.ppat.1003487] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2012] [Accepted: 05/28/2013] [Indexed: 11/30/2022] Open
Abstract
Nef is the viral gene product employed by the majority of primate lentiviruses to overcome restriction by tetherin (BST-2 or CD317), an interferon-inducible transmembrane protein that inhibits the detachment of enveloped viruses from infected cells. Although the mechanisms of tetherin antagonism by HIV-1 Vpu and HIV-2 Env have been investigated in detail, comparatively little is known about tetherin antagonism by SIV Nef. Here we demonstrate a direct physical interaction between SIV Nef and rhesus macaque tetherin, define the residues in Nef required for tetherin antagonism, and show that the anti-tetherin activity of Nef is dependent on clathrin-mediated endocytosis. SIV Nef co-immunoprecipitated with rhesus macaque tetherin and the Nef core domain bound directly to a peptide corresponding to the cytoplasmic domain of rhesus tetherin by surface plasmon resonance. An analysis of alanine-scanning substitutions identified residues throughout the N-terminal, globular core and flexible loop regions of Nef that were required for tetherin antagonism. Although there was significant overlap with sequences required for CD4 downregulation, tetherin antagonism was genetically separable from this activity, as well as from other Nef functions, including MHC class I-downregulation and infectivity enhancement. Consistent with a role for clathrin and dynamin 2 in the endocytosis of tetherin, dominant-negative mutants of AP180 and dynamin 2 impaired the ability of Nef to downmodulate tetherin and to counteract restriction. Taken together, these results reveal that the mechanism of tetherin antagonism by Nef depends on a physical interaction between Nef and tetherin, requires sequences throughout Nef, but is genetically separable from other Nef functions, and leads to the removal of tetherin from sites of virus release at the plasma membrane by clathrin-mediated endocytosis. Tetherin (BST-2, CD317 or HM1.24) is an interferon-inducible cellular restriction factor that prevents the release of enveloped viruses from infected cells. Human and simian immunodeficiency viruses have evolved to use different viral proteins to overcome the anti-viral effects of tetherin. Whereas HIV-1 Vpu and HIV-2 Env counteract human tetherin, most SIVs use the accessory protein Nef to counteract tetherin in their non-human primate hosts. Here we show that the mechanism of tetherin antagonism by SIV Nef involves a direct physical interaction between the core domain of Nef and the cytoplasmic domain of tetherin, which results in the removal of tetherin from sites of virus assembly and release on the cell surface by a mechanism that depends on clathrin and dynamin 2. The Nef-mediated internalization of tetherin leads to the accumulation of tetherin within lysosomal compartments, suggesting that, similar to CD4− and MHC I-downregulation, Nef promotes the lysosomal degradation of tetherin.
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Affiliation(s)
- Ruth Serra-Moreno
- Division of Microbiology, New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts, United States of America
- * E-mail: (RSM); (DTE)
| | - Kerstin Zimmermann
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Lawrence J. Stern
- Department of Pathology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - David T. Evans
- Division of Microbiology, New England Primate Research Center, Harvard Medical School, Southborough, Massachusetts, United States of America
- * E-mail: (RSM); (DTE)
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87
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BST-2/tetherin: Structural biology, viral antagonism, and immunobiology of a potent host antiviral factor. Mol Immunol 2013; 54:132-9. [DOI: 10.1016/j.molimm.2012.11.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 11/20/2012] [Indexed: 12/21/2022]
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88
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Santos da Silva E, Mulinge M, Perez Bercoff D. The frantic play of the concealed HIV envelope cytoplasmic tail. Retrovirology 2013; 10:54. [PMID: 23705972 PMCID: PMC3686653 DOI: 10.1186/1742-4690-10-54] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 05/01/2013] [Indexed: 11/18/2022] Open
Abstract
Lentiviruses have unusually long envelope (Env) cytoplasmic tails, longer than those of other retroviruses. Whereas the Env ectodomain has received much attention, the gp41 cytoplasmic tail (gp41-CT) is one of the least studied parts of the virus. It displays relatively high conservation compared to the rest of Env. It has been long established that the gp41-CT interacts with the Gag precursor protein to ensure Env incorporation into the virion. The gp41-CT contains distinct motifs and domains that mediate both intensive Env intracellular trafficking and interactions with numerous cellular and viral proteins, optimizing viral infectivity. Although they are not fully understood, a multiplicity of interactions between the gp41-CT and cellular factors have been described over the last decade; these interactions illustrate how Env expression and incorporation into virions is a finely tuned process that has evolved to best exploit the host system with minimized genetic information. This review addresses the structure and topology of the gp41-CT of lentiviruses (mainly HIV and SIV), their domains and believed functions. It also considers the cellular and viral proteins that have been described to interact with the gp41-CT, with a particular focus on subtype-related polymorphisms.
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89
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Rogers NM, Isenberg JS, Thomson AW. Plasmacytoid dendritic cells: no longer an enigma and now key to transplant tolerance? Am J Transplant 2013; 13:1125-33. [PMID: 23617754 PMCID: PMC3977341 DOI: 10.1111/ajt.12229] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 02/22/2013] [Accepted: 02/25/2013] [Indexed: 01/25/2023]
Abstract
Plasmacytoid (p) dendritic cells (DC) are a specialized subset of DC whose primary role was initially defined by the production of type I interferons in response to viral infection. They are now known to also possess a repertoire of functions capable of determining T cell fate and activation. Under homeostatic conditions, non-lymphoid tissue-resident pDC play a critical role in the regulation of mucosal immunity, as well as the development of central and peripheral tolerance. Although these cells display a number of characteristics that differ from conventional DC, particularly altered costimulatory molecule expression and poor allostimulatory capacity when interacting with T cells, this phenotype favors the generation of alloantigen-specific regulatory CD4(+) or CD8(+) T cells critical to the development of graft tolerance. In this minireview, we discuss pDC ontogeny, functional biology and the emerging data that demonstrate the importance of pDC in the induction of tolerance, as well as recent studies that define mechanisms underlying pDC-mediated tolerance to both solid organ and haematopoietic stem cell transplants. We also highlight their use in clinical settings and the potential of pDC both as targets and cellular therapeutic agents to improve the outcome of organ transplantation.
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Affiliation(s)
- NM Rogers
- Vascular Medicine Institute, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213,Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
| | - JS Isenberg
- Vascular Medicine Institute, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213,Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213,Division of Pulmonary Allergy and Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213
| | - AW Thomson
- Starzl Transplantation Institute, Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213,Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213,Corresponding author: Angus W. Thomson Ph.D., D.Sc., W1544 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15261, Phone: (412) 624-6392,
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90
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Abstract
Comparing the origins of AIDS and malaria may provide insight for gauging the prospect of future pathogen transmissions from apes to humans.
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Affiliation(s)
- Paul M. Sharp
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JT, UK
| | - Julian C. Rayner
- Malaria Programme, Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | - Beatrice H. Hahn
- Departments of Medicine and Microbiology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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91
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Grover JR, Llewellyn GN, Soheilian F, Nagashima K, Veatch SL, Ono A. Roles played by capsid-dependent induction of membrane curvature and Gag-ESCRT interactions in tetherin recruitment to HIV-1 assembly sites. J Virol 2013; 87:4650-64. [PMID: 23408603 PMCID: PMC3624355 DOI: 10.1128/jvi.03526-12] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 02/04/2013] [Indexed: 12/17/2022] Open
Abstract
Tetherin/BST-2 (here called tetherin) is an antiviral protein that restricts release of diverse enveloped viruses from infected cells through physically tethering virus envelope and host plasma membrane. For HIV-1, specific recruitment of tetherin to assembly sites has been observed as its colocalization with the viral structural protein Gag or its accumulation in virus particles. Because of its broad range of targets, we hypothesized that tetherin is recruited through conserved features shared among various enveloped viruses, such as lipid raft association, membrane curvature, or ESCRT dependence. We observed that reduction of cellular cholesterol does not block tetherin anti-HIV-1 function, excluding an essential role for lipid rafts. In contrast, mutations in the capsid domain of Gag, which inhibit induction of membrane curvature, prevented tetherin-Gag colocalization detectable by confocal microscopy. Disruption of Gag-ESCRT interactions also inhibited tetherin-Gag colocalization when disruption was accomplished via amino acid substitutions in late domain motifs, expression of a dominant-negative Tsg101 derivative, or small interfering RNA (siRNA)-mediated depletion of Tsg101 or Alix. However, further analyses of these conditions by quantitative superresolution localization microscopy revealed that Gag-tetherin coclustering is significantly reduced but persists at intermediate levels. Notably, this residual tetherin recruitment was still sufficient for the full restriction of HIV-1 release. Unlike the late domain mutants, the capsid mutants defective in inducing membrane curvature showed little or no coclustering with tetherin in superresolution analyses. These results support a model in which both Gag-induced membrane curvature and Gag-ESCRT interactions promote tetherin recruitment, but the recruitment level achieved by the former is sufficient for full restriction.
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Affiliation(s)
| | - G. Nicholas Llewellyn
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Ferri Soheilian
- Electron Microscopy Laboratory, SAIC-Frederick, Inc., National Cancer Institute, Frederick, Maryland, USA
| | - Kunio Nagashima
- Electron Microscopy Laboratory, SAIC-Frederick, Inc., National Cancer Institute, Frederick, Maryland, USA
| | - Sarah L. Veatch
- Department of Biophysics, University of Michigan, Ann Arbor, Michigan, USA
| | - Akira Ono
- Department of Microbiology and Immunology
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, Michigan, USA
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92
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Abstract
Acquired immunodeficiency syndrome (AIDS) of humans is caused by two lentiviruses, human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2). Here, we describe the origins and evolution of these viruses, and the circumstances that led to the AIDS pandemic. Both HIVs are the result of multiple cross-species transmissions of simian immunodeficiency viruses (SIVs) naturally infecting African primates. Most of these transfers resulted in viruses that spread in humans to only a limited extent. However, one transmission event, involving SIVcpz from chimpanzees in southeastern Cameroon, gave rise to HIV-1 group M-the principal cause of the AIDS pandemic. We discuss how host restriction factors have shaped the emergence of new SIV zoonoses by imposing adaptive hurdles to cross-species transmission and/or secondary spread. We also show that AIDS has likely afflicted chimpanzees long before the emergence of HIV. Tracing the genetic changes that occurred as SIVs crossed from monkeys to apes and from apes to humans provides a new framework to examine the requirements of successful host switches and to gauge future zoonotic risk.
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Affiliation(s)
- Paul M Sharp
- Institute of Evolutionary Biology and Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
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93
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Dai L, Lidie KB, Chen Q, Adelsberger JW, Zheng X, Huang D, Yang J, Lempicki RA, Rehman T, Dewar RL, Wang Y, Hornung RL, Canizales KA, Lockett SJ, Lane HC, Imamichi T. IL-27 inhibits HIV-1 infection in human macrophages by down-regulating host factor SPTBN1 during monocyte to macrophage differentiation. J Exp Med 2013; 210:517-34. [PMID: 23460728 PMCID: PMC3600911 DOI: 10.1084/jem.20120572] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 01/31/2013] [Indexed: 02/06/2023] Open
Abstract
The susceptibility of macrophages to HIV-1 infection is modulated during monocyte differentiation. IL-27 is an anti-HIV cytokine that also modulates monocyte activation. In this study, we present new evidence that IL-27 promotes monocyte differentiation into macrophages that are nonpermissive for HIV-1 infection. Although IL-27 treatment does not affect expression of macrophage differentiation markers or macrophage biological functions, it confers HIV resistance by down-regulating spectrin β nonerythrocyte 1 (SPTBN1), a required host factor for HIV-1 infection. IL-27 down-regulates SPTBN1 through a TAK-1-mediated MAPK signaling pathway. Knockdown of SPTBN1 strongly inhibits HIV-1 infection of macrophages; conversely, overexpression of SPTBN1 markedly increases HIV susceptibility of IL-27-treated macrophages. Moreover, we demonstrate that SPTBN1 associates with HIV-1 gag proteins. Collectively, our results underscore the ability of IL-27 to protect macrophages from HIV-1 infection by down-regulating SPTBN1, thus indicating that SPTBN1 is an important host target to reduce HIV-1 replication in one major element of the viral reservoir.
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Affiliation(s)
- Lue Dai
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Kristy B. Lidie
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Qian Chen
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Joseph W. Adelsberger
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Xin Zheng
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - DaWei Huang
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Jun Yang
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Richard A. Lempicki
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Tauseef Rehman
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Robin L. Dewar
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Yanmei Wang
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Ronald L. Hornung
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Kelsey A. Canizales
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - Stephen J. Lockett
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
| | - H. Clifford Lane
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Tomozumi Imamichi
- Applied and Developmental Directorate and Advanced Technology Program Directorate, Science Applications International Corporation-Frederick, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702
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94
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Abstract
Tetherin is an interferon-inducible factor that restricts viral particle production. We show here that Sendai virus (SeV) induces a drastic decrease in tetherin levels in infected HeLa cells. Using ectopic expression of tetherin in Madin-Darby canine kidney cells, we find that infectious SeV production is sensitive to restriction by tetherin, suggesting that SeV downregulates tetherin to counter this form of cellular restriction. By using radioactive tetherin in pulse-chase experiments, applying conditions that limit protein degradation, and by estimating tetherin mRNA levels, we find that tetherin degradation is the mechanism of downregulation. Suppression of the virus envelope proteins matrix, fusion (F) or haemagglutinin-neuraminidase protein (HN) during the course of infection demonstrates that F and HN, in concert, are responsible for tetherin degradation. The mechanism(s) by which these two viral glycoproteins participate in degrading tetherin remains to be determined.
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Affiliation(s)
- Carole Bampi
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Lara Rasga
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Laurent Roux
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
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95
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Moffat JM, Segura E, Khoury G, Caminschi I, Cameron PU, Lewin SR, Villadangos JA, Mintern JD. Targeting antigen to bone marrow stromal cell-2 expressed by conventional and plasmacytoid dendritic cells elicits efficient antigen presentation. Eur J Immunol 2013; 43:595-605. [PMID: 23303646 DOI: 10.1002/eji.201242799] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 11/19/2012] [Accepted: 01/04/2013] [Indexed: 11/08/2022]
Abstract
Bone marrow stromal cell-2 (BST-2) has major roles in viral tethering and modulation of interferon production. Here we investigate BST-2 as a receptor for the delivery of antigen to dendritic cells (DCs). We show that BST-2 is expressed by a panel of mouse and human DC subsets, particularly under inflammatory conditions. The outcome of delivering antigen to BST-2 expressed by steady state and activated plasmacytoid DC (pDC) or conventional CD8(+) and CD8(-) DCs was determined. T-cell responses were measured for both MHC class I (MHCI) and MHC class II (MHCII) antigen presentation pathways in vitro. Delivering antigen via BST-2 was compared with that via receptors DEC205 or Siglec-H. We show that despite a higher antigen load and faster receptor internalisation, when antigen is delivered to steady state or activated pDC via BST-2, BST-2-targeted activated conventional DCs present antigen more efficiently. Relative to DEC205, BST-2 was inferior in its capacity to deliver antigen to the MHCI cross-presentation pathway. In contrast, BST-2 was superior to Siglec-H at initiating either MHCI or MHCII antigen presentation. In summary, BST-2 is a useful receptor to target with antigen, given its broad expression pattern and ability to access both MHCI and MHCII presentation pathways with relative efficiency.
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96
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Tokarev A, Suarez M, Kwan W, Fitzpatrick K, Singh R, Guatelli J. Stimulation of NF-κB activity by the HIV restriction factor BST2. J Virol 2013; 87:2046-57. [PMID: 23221546 PMCID: PMC3571454 DOI: 10.1128/jvi.02272-12] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 11/21/2011] [Indexed: 11/20/2022] Open
Abstract
BST2 (HM1.24; CD317; tetherin) is an interferon-inducible transmembrane protein that restricts the release of several enveloped viruses, including HIV, from infected cells. Before its activity as an antiviral factor was described, BST2 was identified as an inducer of NF-κB activity. Here we show that human BST2 induces NF-κB in a dose-dependent manner. This activity is separable from the restriction of virus release: a YxY sequence in the cytoplasmic domain of BST2 is required for the induction of NF-κB but is dispensable for restriction, whereas the glycosylphosphatidylinositol (GPI) addition site in the protein's ectodomain is required for restriction but is largely dispensable for the induction of NF-κB. Mutations predicted to disrupt the coiled-coil structure of the BST2 ectodomain impaired both signaling and restriction, but disruption of the tetramerization interface differentially affected signaling. The induction of NF-κB by BST2 was impaired by inhibition of transforming growth factor β (TGF-β)-activated kinase 1 (TAK1) or by calcium chelation, suggesting potential linkage to the mitogen-activated protein kinase and endoplasmic reticulum (ER) stress response pathways. Consistent with a role for TAK1, BST2 coimmunoprecipitated with TAK1 and the TAK1-associated pseudophosphatase TAB1; these interactions required the YxY sequence in BST2. Moreover, signaling by BST2 was blocked by expression of an IκB-mutant that inhibits the canonical pathway of NF-κB activation. The expression of HIV-1 Vpu inhibited the induction of NF-κB by BST2; this inhibition required Vpu's ability to bind the cellular β-TrCP-E3-ubiquitin ligase complex. The expression of HIV-1 lacking vpu augmented the induction of NF-κB activity by BST2, suggesting that BST2 can act as a virus sensor. This augmentation was also inhibited by Vpu in a β-TrCP-dependent manner. The role of BST2 in the host-pathogen relationship is apparently multifaceted: signaling during the innate immune response, sensing of viral gene expression, and direct restriction of virus release. HIV-1 Vpu counteracts each of these functions.
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Affiliation(s)
- Andrey Tokarev
- The University of California—San Diego, La Jolla California, USA
| | - Marissa Suarez
- The Veterans Affairs San Diego Healthcare System, San Diego, California, USA
| | - Wilson Kwan
- The University of California—San Diego, La Jolla California, USA
| | | | - Rajendra Singh
- The University of California—San Diego, La Jolla California, USA
| | - John Guatelli
- The University of California—San Diego, La Jolla California, USA
- The Veterans Affairs San Diego Healthcare System, San Diego, California, USA
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97
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Pham QT, Veillette M, Brandariz-Nuñez A, Pawlica P, Thibert-Lefebvre C, Chandonnet N, Diaz-Griffero F, Berthoux L. A novel aminoacid determinant of HIV-1 restriction in the TRIM5α variable 1 region isolated in a random mutagenic screen. Virus Res 2013; 173:306-314. [PMID: 23357295 DOI: 10.1016/j.virusres.2013.01.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 01/16/2013] [Accepted: 01/17/2013] [Indexed: 12/31/2022]
Abstract
Human-derived antiretroviral transgenes are of great biomedical interest and are actively pursued. HIV-1 is efficiently inhibited at post-entry, pre-integration replication stages by point mutations in the variable region 1 (v1) of the human restriction factor TRIM5α. Here we use a mutated megaprimer approach to create a mutant library of TRIM5αHu v1 and to isolate a mutation at Gly330 (G330E) that inhibits transduction of an HIV-1 vector as efficiently as the previously described mutants at positions Arg332 and Arg335. As was the case for these other mutations, modification of the local v1 charge toward increased acidity was key to inhibiting HIV-1. G330E TRIM5αHu also disrupted replication-competent HIV-1 propagation in a human T cell line. Interestingly, G330E did not enhance restriction of HIV-1 when combined with mutations at Arg332 or Arg335. Accordingly, the triple mutant G330E-R332G-R335G bound purified recombinant HIV-1 capsid tubes less efficiently than the double mutant R332G-R335G did. In a structural model of the TRIM5αHu PRYSPRY domain, the addition of G330E to the double mutant R332G-R335G caused extensive changes to the capsid-binding surface, which may explain why the triple mutant was no more restrictive than the double mutant. The HIV-1 inhibitory potential of Gly330 mutants was not predicted by examination of natural TRIM5α orthologs that are known to strongly inhibit HIV-1. This work underlines the potential of random mutagenesis to isolate novel variants of human proteins with antiviral properties.
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Affiliation(s)
- Quang Toan Pham
- Laboratory of Retrovirology, Department of Medical Biology, Université du Québec à Trois-Rivières, 3351 Boulevard des Forges, CP500, Trois-Rivières, QC, G9A 5H7, Canada
| | - Maxime Veillette
- Laboratory of Retrovirology, Department of Medical Biology, Université du Québec à Trois-Rivières, 3351 Boulevard des Forges, CP500, Trois-Rivières, QC, G9A 5H7, Canada
| | - Alberto Brandariz-Nuñez
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1301 Morris Park-Price Center 501, Bronx, NY 10461, USA
| | - Paulina Pawlica
- Laboratory of Retrovirology, Department of Medical Biology, Université du Québec à Trois-Rivières, 3351 Boulevard des Forges, CP500, Trois-Rivières, QC, G9A 5H7, Canada
| | - Caroline Thibert-Lefebvre
- Laboratory of Retrovirology, Department of Medical Biology, Université du Québec à Trois-Rivières, 3351 Boulevard des Forges, CP500, Trois-Rivières, QC, G9A 5H7, Canada
| | - Nadia Chandonnet
- Laboratory of Retrovirology, Department of Medical Biology, Université du Québec à Trois-Rivières, 3351 Boulevard des Forges, CP500, Trois-Rivières, QC, G9A 5H7, Canada
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1301 Morris Park-Price Center 501, Bronx, NY 10461, USA
| | - Lionel Berthoux
- Laboratory of Retrovirology, Department of Medical Biology, Université du Québec à Trois-Rivières, 3351 Boulevard des Forges, CP500, Trois-Rivières, QC, G9A 5H7, Canada
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98
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Johnson WE. Rapid adversarial co-evolution of viruses and cellular restriction factors. Curr Top Microbiol Immunol 2013; 371:123-51. [PMID: 23686234 DOI: 10.1007/978-3-642-37765-5_5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Since the discovery of viruses over a century ago, virologists have recognized that host genetics plays a major role in viral tropism and the distribution of viruses in nature. Traditionally, studies of tropism have centered on identification of cellular factors required for viral replication, such as cell-surface entry receptors. However, over the past 20 years, there has been a steady increase in the identification and characterization of restriction factors (RFs), here defined as dominant cellular factors that have evolved specifically to interfere with viral replication. Genetic studies suggest that restriction factors impose significant barriers to interspecies movement of viruses and are therefore critical determinants of viral tropism. Furthermore, the scope of the ever-expanding list of restriction factors, and the variety of antiviral mechanisms they represent, testifies to the extraordinary impact viruses have had on organismal evolution-an impact hitherto underappreciated by evolutionary biologists and virologists alike. Recent studies of RF-encoding genes that combine molecular evolutionary analysis with functional assays illustrate the potential for asking questions about virus-host interactions as they play out in natural populations and across evolutionary timescales. Most notably, it has become common to apply tests of positive selection to RF genes and couple these analyses with virological assays, to reveal evidence for antagonistic virus-host co-evolution. Herein, I summarize recent work on the evolutionary genetics of mammalian RFs, particularly those of humans, non-human primates, and model organisms, and how RFs can reveal the influence of virus-host interactions on organismal evolution. Because intensive investigation of RF evolution is fairly new (and because there is still much to learn), the discussion is organized around five broad, outstanding questions that will need to be answered before we can fully appreciate the evolutionary biology of restriction.
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99
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[Multifunctional HIV accessory proteins are hub proteins antagonizing host antiviral factors]. Uirusu 2013; 63:187-98. [PMID: 25366053 DOI: 10.2222/jsv.63.187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
HIV has several accessory proteins (Vif, Vpu, Vpr, Vpx, and Nef) along with structural /enzymatic (Gag, Pol, and Env) and gene-expression regulatory proteins (Tat and Rev) essential for viral replication. The accessory proteins are neither required in some kinds of cells and nor all conserved between HIV-1 and HIV-2. For these reasons, their functional roles and mechanisms had been unclear. However, since a finding of Vif's neutralizing function against host restriction factor APOBEC3G, it has been elucidated that the accessory proteins play critical roles to antagonize host intrinsic antiviral activity. So far, in addition to Vif-APOBEC3, Vpu-BST-2/Tetherin and Vpx-SAMHD1 have been identified as such examples. Here, we summarize the biological functions and features on HIV accessory proteins in terms of antagonizing factors against the host antiviral factors.
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100
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Abstract
Envelope glycoproteins (Env) of lentiviruses typically possess unusually long cytoplasmic domains, often 150 amino acids or longer. It is becoming increasingly clear that these sequences contribute a diverse array of functional activities to the life cycle of their viruses. The cytoplasmic domain of gp41 (gp41CD) is required for replication of human immunodeficiency virus type 1 (HIV-1) in most but not all cell types, whereas it is largely dispensable for replication of simian immunodeficiency virus (SIV). Functionally, gp41CD has been shown to regulate rapid clathrin-mediated endocytosis of Env. The resultant low levels of Env expression at the cell surface likely serve as an immune avoidance mechanism to limit accessibility to the humoral immune response. Intracellular trafficking of Env is also regulated by gp41CD through interactions with a variety of cellular proteins. Furthermore, gp41CD has been implicated in the incorporation of Env into virions through an interaction with the virally encoded matrix protein. Most recently, the gp41CDs of HIV-1 and SIV were shown to activate the key cellular-transcription factor NF-κB via the serine/threonine kinase TAK1. Less well understood are the cytotoxicity- and apoptosis-inducing activities of gp41CD as well as potential roles in modulating the actin cytoskeleton and overcoming host cell restrictions. In this review, we summarize what is currently known about the cytoplasmic domains of HIV-1 and SIV and attempt to integrate the wealth of information in terms of defined functional activities.
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Affiliation(s)
- Thomas S. Postler
- New England Primate Research Center, Department of Microbiology and Immunobiology, Harvard Medical School, Southborough, Massachusetts, USA
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Ronald C. Desrosiers
- New England Primate Research Center, Department of Microbiology and Immunobiology, Harvard Medical School, Southborough, Massachusetts, USA
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