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Sperber HS, Raymond KA, Bouzidi MS, Ma T, Valdebenito S, Eugenin EA, Roan NR, Deeks SG, Winning S, Fandrey J, Schwarzer R, Pillai SK. The hypoxia-regulated ectonucleotidase CD73 is a host determinant of HIV latency. Cell Rep 2023; 42:113285. [PMID: 37910505 PMCID: PMC10838153 DOI: 10.1016/j.celrep.2023.113285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 07/04/2023] [Accepted: 09/29/2023] [Indexed: 11/03/2023] Open
Abstract
Deciphering the mechanisms underlying viral persistence is critical to achieving a cure for human immunodeficiency virus (HIV) infection. Here, we implement a systems approach to discover molecular signatures of HIV latently infected CD4+ T cells, identifying the immunosuppressive, adenosine-producing ectonucleotidase CD73 as a key surface marker of latent cells. Hypoxic conditioning, reflecting the lymphoid tissue microenvironment, increases the frequency of CD73+ CD4+ T cells and promotes HIV latency. Transcriptomic profiles of CD73+ CD4+ T cells favor viral quiescence, immune evasion, and cell survival. CD73+ CD4+ T cells are capable of harboring a functional HIV reservoir and reinitiating productive infection ex vivo. CD73 or adenosine receptor blockade facilitates latent HIV reactivation in vitro, mechanistically linking adenosine signaling to viral quiescence. Finally, tissue imaging of lymph nodes from HIV-infected individuals on antiretroviral therapy reveals spatial association between CD73 expression and HIV persistence in vivo. Our findings warrant development of HIV-cure strategies targeting the hypoxia-CD73-adenosine axis.
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Affiliation(s)
- Hannah S Sperber
- Vitalant Research Institute, San Francisco, CA, USA; Free University of Berlin, Institute of Biochemistry, Berlin, Germany; University of California, San Francisco, San Francisco, CA, USA; University Hospital Essen, Institute for Translational HIV Research, Essen, Germany
| | - Kyle A Raymond
- Vitalant Research Institute, San Francisco, CA, USA; University of California, San Francisco, San Francisco, CA, USA
| | - Mohamed S Bouzidi
- Vitalant Research Institute, San Francisco, CA, USA; University of California, San Francisco, San Francisco, CA, USA
| | - Tongcui Ma
- University of California, San Francisco, San Francisco, CA, USA; Gladstone Institutes, San Francisco, CA, USA
| | | | | | - Nadia R Roan
- University of California, San Francisco, San Francisco, CA, USA; Gladstone Institutes, San Francisco, CA, USA
| | - Steven G Deeks
- University of California, San Francisco, San Francisco, CA, USA
| | - Sandra Winning
- University of Duisburg-Essen, Institute for Physiology, Essen, Germany
| | - Joachim Fandrey
- University of Duisburg-Essen, Institute for Physiology, Essen, Germany
| | - Roland Schwarzer
- University Hospital Essen, Institute for Translational HIV Research, Essen, Germany.
| | - Satish K Pillai
- Vitalant Research Institute, San Francisco, CA, USA; University of California, San Francisco, San Francisco, CA, USA.
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2
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Li J, Huang HH, Tu B, Zhou MJ, Hu W, Fu YL, Li XY, Yang T, Song JW, Fan X, Jiao YM, Xu RN, Zhang JY, Zhou CB, Yuan JH, Zhen C, Shi M, Wang FS, Zhang C. Reversal of the CD8 + T-Cell Exhaustion Induced by Chronic HIV-1 Infection Through Combined Blockade of the Adenosine and PD-1 Pathways. Front Immunol 2021; 12:687296. [PMID: 34177939 PMCID: PMC8222537 DOI: 10.3389/fimmu.2021.687296] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 05/18/2021] [Indexed: 12/15/2022] Open
Abstract
Background Targeting immune checkpoints for HIV treatment potentially provides a double benefit resulting from the ability to restore viral-specific CD8+ T-cell functions and enhance HIV production from reservoir cells. Despite promising pre-clinical data, PD-1 blockade alone in HIV-1-infected patients with advanced cancer has shown limited benefits in controlling HIV, suggesting the need for additional targets beyond PD-1. CD39 and PD-1 are highly co-expressed on CD8+ T cells in HIV-1 infection. However, the characteristics of CD39 and PD-1 dual-positive CD8+ T-cell subsets in chronic HIV-1 infection remain poorly understood. Methods This study enrolled 72 HIV-1-infected patients, including 40 treatment naïve and 32 ART patients. A total of 11 healthy individuals were included as controls. Different subsets of CD8+ T cells defined by CD39 and/or PD-1 expression were studied by flow cytometry. The relationships between the frequencies of the different subsets and parameters indicating HIV-1 disease progression were analyzed. Functional (i.e., cytokine secretion, viral inhibition) assays were performed to evaluate the impact of the blockade of adenosine and/or PD-1 signaling on CD8+ T cells. Results The proportions of PD-1+, CD39+, and PD-1+CD39+ CD8+ T cells were significantly increased in treatment naïve patients but were partially lowered in patients on antiretroviral therapy. In treatment naïve patients, the proportions of PD-1+CD39+ CD8+ T cells were negatively correlated with CD4+ T-cell counts and the CD4/CD8 ratio, and were positively correlated with viral load. CD39+CD8+ T cells expressed high levels of the A2A adenosine receptor and were more sensitive to 2-chloroadenosine-mediated functional inhibition than their CD39- counterparts. In vitro, a combination of blocking CD39/adenosine and PD-1 signaling showed a synergic effect in restoring CD8+ T-cell function, as evidenced by enhanced abilities to secrete functional cytokines and to kill autologous reservoir cells. Conclusion In patients with chronic HIV-1 infection there are increased frequencies of PD-1+, CD39+, and PD-1+CD39+ CD8+ T cells. In treatment naïve patients, the frequencies of PD-1+CD39+ CD8+ T cells are negatively correlated with CD4+ T-cell counts and the CD4/CD8 ratio and positively correlated with viral load. Combined blockade of CD39/adenosine and PD-1 signaling in vitro may exert a synergistic effect in restoring CD8+ T-cell function in HIV-1-infected patients.
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Affiliation(s)
- Jing Li
- Peking University 302 Clinical Medical School, Beijing, China.,Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Hui-Huang Huang
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Bo Tu
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Ming-Ju Zhou
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Wei Hu
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China.,Medical School of Chinese PLA, Beijing, China
| | - Yu-Long Fu
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China.,Savaid Medical School, University of Chinese Academy of Sciences, Beijing, China
| | - Xiao-Yu Li
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China.,Bengbu Medical University, Bengbu, China
| | - Tao Yang
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China.,Medical School of Chinese PLA, Beijing, China
| | - Jin-Wen Song
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Xing Fan
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Yan-Mei Jiao
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Ruo-Nan Xu
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Ji-Yuan Zhang
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Chun-Bao Zhou
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Jin-Hong Yuan
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Cheng Zhen
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Ming Shi
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Fu-Sheng Wang
- Peking University 302 Clinical Medical School, Beijing, China.,Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
| | - Chao Zhang
- Department of Infectious Diseases, The Fifth Medical Center of Chinese PLA General Hospital, National Clinical Research Center for Infectious Diseases, Beijing, China
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3
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Cardozo EF, Apetrei C, Pandrea I, Ribeiro RM. The dynamics of simian immunodeficiency virus after depletion of CD8+ cells. Immunol Rev 2019; 285:26-37. [PMID: 30129200 DOI: 10.1111/imr.12691] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Human immunodeficiency virus infection is still one of the most important causes of morbidity and mortality in the world, with a disproportionate human and economic burden especially in poorer countries. Despite many years of intense research, an aspect that still is not well understood is what (immune) mechanisms control the viral load during the prolonged asymptomatic stage of infection. Because CD8+ T cells have been implicated in this control by multiple lines of evidence, there has been a focus on understanding the potential mechanisms of action of this immune effector population. One type of experiment used to this end has been depleting these cells with monoclonal antibodies in the simian immunodeficiency virus-macaque model and then studying the effect of that depletion on the viral dynamics. Here we review what these experiments have told us. We emphasize modeling studies to interpret the changes in viral load observed in these experiments, including discussion of alternative models, assumptions and interpretations, as well as potential future experiments.
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Affiliation(s)
- Erwing Fabian Cardozo
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Cristian Apetrei
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Ivona Pandrea
- Center for Vaccine Research, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Ruy M Ribeiro
- Theoretical Biology and Biophysics Group, Los Alamos National Laboratory, Los Alamos, New Mexico.,Laboratorio de Biomatematica, Faculdade de Medicina da Universidade de Lisboa, Portugal
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4
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Plumelle Y. HIV, 'an evolving species'. Roles of cellular activation and co-infections. Med Hypotheses 2003; 61:136-57. [PMID: 12781657 DOI: 10.1016/s0306-9877(03)00147-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Each small variation of the genome of a species can be preserved if it is useful for the survival of the species in a given environment. Within this framework, the finality of the biological cycle of HIV consists in a search for harmony (biological coherence) with man, which is to say a stable condition. Cellular activation appears to be the strategy developed by HIV in order to achieve this coherence. The price of this strategy is the AIDS. The first contact between HIV and immune system appears to determine the subsequent clinical outcome and the future of HIV. Lymphocytic activation varies during the course of the vital cycle of HIV. For each individual, this lymphocytic activation depends on both the HLA repertoire acquired during thymic ontogenesis and the antigenic experience before and after HIV infection. Thus intercurrent infections alter the immune condition of the organism and influence the outcome of HIV. We described a synthetic analysis of the effects of HIV on the surface protein expression and the cellular activation pathways which should provide insights in the evolutionary relationship between HIV and man and should permit to do a more physiological therapeutic approach.
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Affiliation(s)
- Yves Plumelle
- Department of Hematobiology, University Hospital, France.
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5
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Kutsch O, Vey T, Kerkau T, Hünig T, Schimpl A. HIV type 1 abrogates TAP-mediated transport of antigenic peptides presented by MHC class I. Transporter associated with antigen presentation. AIDS Res Hum Retroviruses 2002; 18:1319-25. [PMID: 12487820 DOI: 10.1089/088922202320886361] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Downregulation of MHC class I expression following human immunodeficiency virus 1 (HIV-1) infection is thought to play an important role in viral escape from immune recognition by cytotoxic T-lymphocytes (CTLs). Since exogenous addition of HIV-1-derived peptides restores susceptibility of HIV-1-infected cells to CTL-mediated lysis, we tested whether endogenous peptide loading is impaired in these cells. Our results show that in HIV-1-infected cells the ability of the transporter associated with antigen presentation (TAP) to translocate antigenic peptides from the cytosol to the lumen of the ER for presentation on MHC class I molecules is abolished. These data suggest that interference with the supply of antigenic peptides to the MHC class I pathway provides an additional mechanism by which HIV-1 evades the CTL-mediated immune response.
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Affiliation(s)
- O Kutsch
- Institute of Immunobiology and Virology, The Julius-Maximilians University, Würzburg, Germany.
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6
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Evasion of the immune system by tumor viruses. ACTA ACUST UNITED AC 2001. [DOI: 10.1016/s0168-7069(01)05014-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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7
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Peters VB, Sperber KE. The effect of viruses on the ability to present antigens via the major histocompatibility complex. Microbes Infect 1999; 1:335-45. [PMID: 10602667 DOI: 10.1016/s1286-4579(99)80029-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe viral pathogens that cause significant human disease by their ability to interfere with the expression of major histocompatibility complex class I and II molecules. Herpesviruses and papillomaviruses encode gene products that interfere with the class I pathway of antigen processing and/or peptide translocation. Adenoviruses encode unique gene products that interfere with transport of class I molecules. Influenza virus, measles virus, and HIV interfere with the class II pathway by either suppressing the production of class II molecules or impeding antigen trafficking. Cytomegalovirus interferes with both class I and class II pathways. Better understanding of these mechanisms may lead to further insight into the pathogenesis of viral infections and allow for improved treatments.
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Affiliation(s)
- V B Peters
- Department of Pediatrics, Mount Sinai School of Medicine, New York, NY 10029, USA
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8
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Tsai WP, Kung HF, Nara PL. The presence and absence of histocompatibility antigens in HIV type 1 produced by autologous blood-derived macrophages and peripheral blood lymphoblasts. AIDS Res Hum Retroviruses 1999; 15:33-41. [PMID: 10024050 DOI: 10.1089/088922299311682] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022] Open
Abstract
Acquisition of cellular proteins by HIV-1 virions is known to alter the physiology of the virus in vitro. Reported studies of this aspect have been largely limited to transformed T cell lines. In this study, we investigated the incorporation of major histocompatibility antigens (HLAs) on a primary macrophage-tropic isolate, HIV-1ADA, grown from autologous monocyte-derived macrophages (MDMs) and peripheral blood mononuclear cells (PBMCs). A virus precipitation assay (VPA) demonstrated that HIV-1ADA grown from PBMCs incorporated substantial amounts of HLA class I (alpha chain and beta2m) and DR antigens, comparable with a laboratory strain, HIV-1MN, grown from the same host cells. HIV-1ADA, however, grown from MDMs incorporated significantly lower amounts of HLAI and -II antigens despite the fact that the infected MDMs were found to express significant amounts of HLA antigens. The lack of incorporation of these important immunomodulatory cell surface proteins may be yet another unique characteristic of macrophage-tropic isolates and suggests a possible role in their biology and or immunology.
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Affiliation(s)
- W P Tsai
- Laboratory of Biochemical Physiology, NCI/FCRDC, Frederick, Maryland 21702, USA.
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9
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Ehrlich R. Modulation of antigen processing and presentation by persistent virus infections and in tumors. Hum Immunol 1997; 54:104-16. [PMID: 9297529 DOI: 10.1016/s0198-8859(97)00083-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Cell-mediated immunity is effective against cells harboring active virus replication and is critical for the elimination of ongoing infections, opposing tumor progression, and reducing or preventing the reactivation of persistent viruses and tumor metastasis. The capacity of persistent viruses and tumor cells to maintain a long-term relationship with their host presupposes mechanisms for circumventing antiviral or antitumor defenses. By suppressing the expression of molecules associated with antigen processing and presentation, abrogation of the major immune mechanism that deals with the elimination of infected and transformed cells is achieved. This is accomplished in tumors predominantly by transcriptional downregulation of genes encoding class I major histocompatibility complex antigens, peptide transporter molecules, and the proteasome-associated low molecular mass protease subunits, and in cells expressing viral proteins by interfering with peptide transport and the assembly/transport of class I complexes. In addition, virus-infected cells and selected tumor cells express mainly nonimmunogenic or antagonistic peptide epitopes. This review describes mechanisms used by viruses and in transformed cells for interference with antigen processing and presentation and addresses their significance for in vivo viral persistence and tumor progression.
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Affiliation(s)
- R Ehrlich
- Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel
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10
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Kerkau T, Bacik I, Bennink JR, Yewdell JW, Húnig T, Schimpl A, Schubert U. The human immunodeficiency virus type 1 (HIV-1) Vpu protein interferes with an early step in the biosynthesis of major histocompatibility complex (MHC) class I molecules. J Exp Med 1997; 185:1295-305. [PMID: 9104816 PMCID: PMC2196253 DOI: 10.1084/jem.185.7.1295] [Citation(s) in RCA: 141] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) vpu gene encodes a small integral membrane phosphoprotein with two established functions: degradation of the viral coreceptor CD4 in the endoplasmic reticulum (ER) and augmentation of virus particle release from the plasma membrane of HIV-1-infected cells. We show here that Vpu is also largely responsible for the previously observed decrease in the expression of major histocompatibility complex (MHC) class I molecules on the surface of HIV-1-infected cells. Cells infected with HIV-1 isolates that fail to express Vpu, or that express genetically modified forms of Vpu that no longer induce CD4 degradation, exhibit little downregulation of MHC class I molecules. The effect of Vpu on class I biogenesis was analyzed in more detail using a Vpu-expressing recombinant vaccinia virus (VV). VV-expressed Vpu induces the rapid loss of newly synthesized endogenous or VV-expressed class I heavy chains in the ER, detectable either biochemically or by reduced cell surface expression. This effect is of similar rapidity and magnitude as the VV-expressed Vpu-induced degradation of CD4. Vpu had no discernible effects on cell surface expression of VV-expressed mouse CD54, demonstrating the selectivity of its effects on CD4 and class I heavy chains. VV-expressed Vpu does not detectably affect class I molecules that have been exported from the ER. The detrimental effects of Vpu on class I molecules could be distinguished from those caused by VV-expressed herpes virus protein ICP47, which acts by decreasing the supply of cytosolic peptides to class I molecules, indicating that Vpu functions in a distinct manner from ICP47. Based on these findings, we propose that Vpu-induced downregulation of class I molecules may be an important factor in the evolutionary selection of the HIV-1-specific vpu gene by contributing to the inability of CD8+ T cells to eradicate HIV-1 from infected individuals.
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Affiliation(s)
- T Kerkau
- Institute of Virology and Immunobiology, University of Würzburg, Germany
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11
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Ehrlich R. Selective mechanisms utilized by persistent and oncogenic viruses to interfere with antigen processing and presentation. Immunol Res 1995; 14:77-97. [PMID: 8530879 DOI: 10.1007/bf02918170] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cell-mediated immunity is effective against cells harboring active virus replication, and is critical for the elimination of ongoing infections, regression of virus-associated tumors, and reducing or preventing the reactivation of persistent viruses. The capacity of persistent and oncogenic viruses to maintain a long-term relationship with their host presupposes viral mechanisms for circumventing antiviral defenses. By suppressing the expression of molecules associated with antigen processing and presentation, viruses abrogate the major immune mechanism that deals with the elimination of infected and tumor cells. This is accomplished either by transcriptional downregulation of genes encoding class I MHC antigens, peptide transporter molecules, and the proteasome-associated LMP subunits, or by interfering with transport of class I molecules to the cell surface. In some cases viruses shut off the expression of most viral proteins during latency or express mainly nonimmunogenic or antagonistic peptide epitopes. This review describes selective mechanisms utilized by viruses for interference with antigen processing and presentation, and addresses their significance for in vivo viral persistence and tumor progression.
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Affiliation(s)
- R Ehrlich
- Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel
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12
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Bour S, Geleziunas R, Wainberg MA. The human immunodeficiency virus type 1 (HIV-1) CD4 receptor and its central role in promotion of HIV-1 infection. Microbiol Rev 1995; 59:63-93. [PMID: 7708013 PMCID: PMC239355 DOI: 10.1128/mr.59.1.63-93.1995] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Interactions between the viral envelope glycoprotein gp120 and the cell surface receptor CD4 are responsible for the entry of human immunodeficiency virus type 1 (HIV-1) into host cells in the vast majority of cases. HIV-1 replication is commonly followed by the disappearance or receptor downmodulation of cell surface CD4. This potentially renders cells nonsusceptible to subsequent infection by HIV-1, as well as by other viruses that use CD4 as a portal of entry. Disappearance of CD4 from the cell surface is mediated by several different viral proteins that act at various stages through the course of the viral life cycle, and it occurs in T-cell lines, peripheral blood CD4+ lymphocytes, and monocytes of both primary and cell line origin. At the cell surface, gp120 itself and in the form of antigen-antibody complexes can trigger cellular pathways leading to CD4 internalization. Intracellularly, the mechanisms leading to CD4 downmodulation by HIV-1 are multiple and complex; these include degradation of CD4 by Vpu, formation of intracellular complexes between CD4 and the envelope precursor gp160, and internalization by the Nef protein. Each of the above doubtless contributes to the ultimate depletion of cell surface CD4, although the relative contribution of each mechanism and the manner in which they interact remain to be definitively established.
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Affiliation(s)
- S Bour
- McGill AIDS Centre, Lady Davis Institute-Jewish General Hospital, Montreal, Quebec, Canada
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13
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Morris A, Hewitt C, Young S. The major histocompatibility complex: its genes and their roles in antigen presentation. Mol Aspects Med 1994; 15:377-503. [PMID: 7837935 DOI: 10.1016/0098-2997(94)90041-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- A Morris
- Department of Biological Sciences, University of Warwick, Coventry, U.K
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