351
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Furuya AKM, Sharifi HJ, de Noronha CMC. The Curious Case of Type I IFN and MxA: Tipping the Immune Balance in AIDS. Front Immunol 2014; 5:419. [PMID: 25228901 PMCID: PMC4151092 DOI: 10.3389/fimmu.2014.00419] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 08/18/2014] [Indexed: 01/30/2023] Open
Affiliation(s)
| | - Hamayun J Sharifi
- Albany Medical Center, Center for Immunology and Microbial Disease , Albany, NY , USA
| | - Carlos M C de Noronha
- Albany Medical Center, Center for Immunology and Microbial Disease , Albany, NY , USA
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352
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HIV-1 Vpr induces interferon-stimulated genes in human monocyte-derived macrophages. PLoS One 2014; 9:e106418. [PMID: 25170834 PMCID: PMC4149569 DOI: 10.1371/journal.pone.0106418] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 08/06/2014] [Indexed: 01/24/2023] Open
Abstract
Macrophages act as reservoirs of human immunodeficiency virus type 1 (HIV-1) and play an important role in its transmission to other cells. HIV-1 Vpr is a multi-functional protein involved in HIV-1 replication and pathogenesis; however, its exact role in HIV-1-infected human macrophages remains poorly understood. In this study, we used a microarray approach to explore the effects of HIV-1 Vpr on the transcriptional profile of human monocyte-derived macrophages (MDMs). More than 500 genes, mainly those involved in the innate immune response, the type I interferon pathway, cytokine production, and signal transduction, were differentially regulated (fold change >2.0) after infection with a recombinant adenovirus expressing HIV-1 Vpr protein. The differential expression profiles of select interferon-stimulated genes (ISGs) and genes involved in the innate immune response, including STAT1, IRF7, MX1, MX2, ISG15, ISG20, IFIT1, IFIT2, IFIT3, IFI27, IFI44L, APOBEC3A, DDX58 (RIG-I), TNFSF10 (TRAIL), and RSAD2 (viperin) were confirmed by real-time quantitative PCR and were consistent with the microarray data. In addition, at the post-translational level, HIV-1 Vpr induced the phosphorylation of STAT1 at tyrosine 701 in human MDMs. These results demonstrate that HIV-1 Vpr leads to the induction of ISGs and expand the current understanding of the function of Vpr and its role in HIV-1 immune pathogenesis.
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353
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Beiting DP. Protozoan parasites and type I interferons: a cold case reopened. Trends Parasitol 2014; 30:491-8. [PMID: 25153940 DOI: 10.1016/j.pt.2014.07.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 07/23/2014] [Accepted: 07/24/2014] [Indexed: 01/12/2023]
Abstract
Protozoan parasites, such as Plasmodium, Toxoplasma, Cryptosporidium, trypanosomes, and Leishmania, are a major cause of disease in both humans and other animals, highlighting the need to understand the full spectrum of strategies used by the host immune system to sense and respond to parasite infection. Although type II interferon (IFN-γ) has long been recognized as an essential antiparasite immune effector, much less is known about the role of type I interferons (IFN-α and -β) in host defense, particularly in vivo. Recent studies are reviewed which collectively highlight that type I IFN can be induced in response to parasite infection and influence the outcome of infection.
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Affiliation(s)
- Daniel P Beiting
- Department of Pathobiology, University of Pennsylvania, Philadelphia, PA, USA.
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354
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Fricke T, White TE, Schulte B, de Souza Aranha Vieira DA, Dharan A, Campbell EM, Brandariz-Nuñez A, Diaz-Griffero F. MxB binds to the HIV-1 core and prevents the uncoating process of HIV-1. Retrovirology 2014; 11:68. [PMID: 25123063 PMCID: PMC4145229 DOI: 10.1186/s12977-014-0068-x] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 07/30/2014] [Indexed: 01/23/2023] Open
Abstract
Background The IFN-α-inducible restriction factor MxB blocks HIV-1 infection after reverse transcription but prior to integration. Genetic evidence suggested that capsid is the viral determinant for restriction by MxB. This work explores the ability of MxB to bind to the HIV-1 core, and the role of capsid-binding in restriction. Results We showed that MxB binds to the HIV-1 core and that this interaction leads to inhibition of the uncoating process of HIV-1. These results identify MxB as an endogenously expressed protein with the ability to inhibit HIV-1 uncoating. In addition, we found that a benzimidazole-based compound known to have a binding pocket on the surface of the HIV-1 capsid prevents the binding of MxB to capsid. The use of this small-molecule identified the MxB binding region on the surface of the HIV-1 core. Domain mapping experiments revealed the following requirements for restriction: 1) MxB binding to the HIV-1 capsid, which requires the 20 N-terminal amino acids, and 2) oligomerization of MxB, which is mediated by the C-terminal domain provides the avidity for the interaction of MxB with the HIV-1 core. Conclusions Overall our work establishes that MxB binds to the HIV-1 core and inhibits the uncoating process of HIV-1. Moreover, we demonstrated that HIV-1 restriction by MxB requires capsid binding and oligomerization. Electronic supplementary material The online version of this article (doi:10.1186/s12977-014-0068-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | | | | | | | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx 10461, NY, USA.
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355
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Le Sage V, Mouland AJ, Valiente-Echeverría F. Roles of HIV-1 capsid in viral replication and immune evasion. Virus Res 2014; 193:116-29. [PMID: 25036886 DOI: 10.1016/j.virusres.2014.07.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/04/2014] [Accepted: 07/07/2014] [Indexed: 02/07/2023]
Abstract
The primary roles of the human immunodeficiency virus type 1 (HIV-1) capsid (CA) protein are to encapsidate and protect the viral RNA genome. It is becoming increasing apparent that HIV-1 CA is a multifunctional protein that acts early during infection to coordinate uncoating, reverse transcription, nuclear import of the pre-integration complex and integration of double stranded viral DNA into the host genome. Additionally, numerous recent studies indicate that CA is playing a crucial function in HIV-1 immune evasion. Here we summarize the current knowledge on HIV-1 CA and its interactions with the host cell to promote infection. The fact that CA engages in a number of different protein-protein interactions with the host makes it an interesting target for the development of new potent antiviral agents.
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Affiliation(s)
- Valerie Le Sage
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute, Jewish General Hospital, Montréal, Québec H3T1E2, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada
| | - Andrew J Mouland
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute, Jewish General Hospital, Montréal, Québec H3T1E2, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada; Department of Microbiology and Immunology, McGill University, Montréal, Québec, H3A2B4, Canada
| | - Fernando Valiente-Echeverría
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute, Jewish General Hospital, Montréal, Québec H3T1E2, Canada; Department of Medicine, Division of Experimental Medicine, McGill University, Montréal, Québec H3A 1A3, Canada.
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356
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Abstract
HIV-1 was recognized as the cause of AIDS in humans in 1984. Despite 30 years of intensive research, we are still unraveling the molecular details of the host-pathogen interactions that enable this virus to escape immune clearance and cause immunodeficiency. Here we explore a series of recent studies that consider how HIV-1 interacts with the cell-autonomous innate immune system as it navigates its way in and out of host cells. We discuss how these studies improve our knowledge of HIV-1 and host biology as well as increase our understanding of transmission, persistence, and immunodeficiency and the potential for therapeutic or prophylactic interventions.
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Affiliation(s)
- Greg J Towers
- Division of Infection and Immunity, University College London, London W1CE 6BT, UK.
| | - Mahdad Noursadeghi
- Division of Infection and Immunity, University College London, London W1CE 6BT, UK
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357
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Nguyen PV, Kafka JK, Ferreira VH, Roth K, Kaushic C. Innate and adaptive immune responses in male and female reproductive tracts in homeostasis and following HIV infection. Cell Mol Immunol 2014; 11:410-27. [PMID: 24976268 DOI: 10.1038/cmi.2014.41] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 05/08/2014] [Indexed: 12/13/2022] Open
Abstract
The male and female reproductive tracts are complex microenvironments that have diverse functional demands. The immune system in the reproductive tract has the demanding task of providing a protective environment for a fetal allograft while simultaneously conferring protection against potential pathogens. As such, it has evolved a unique set of adaptations, primarily under the influence of sex hormones, which make it distinct from other mucosal sites. Here, we discuss the various components of the immune system that are present in both the male and female reproductive tracts, including innate soluble factors and cells and humoral and cell-mediated adaptive immunity under homeostatic conditions. We review the evidence showing unique phenotypic and functional characteristics of immune cells and responses in the male and female reproductive tracts that exhibit compartmentalization from systemic immunity and discuss how these features are influenced by sex hormones. We also examine the interactions among the reproductive tract, sex hormones and immune responses following HIV-1 infection. An improved understanding of the unique characteristics of the male and female reproductive tracts will provide insights into improving clinical treatments of the immunological causes of infertility and the design of prophylactic interventions for the prevention of sexually transmitted infections.
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358
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Sironi M, Biasin M, Cagliani R, Gnudi F, Saulle I, Ibba S, Filippi G, Yahyaei S, Tresoldi C, Riva S, Trabattoni D, De Gioia L, Lo Caputo S, Mazzotta F, Forni D, Pontremoli C, Pineda JA, Pozzoli U, Rivero-Juarez A, Caruz A, Clerici M. Evolutionary analysis identifies an MX2 haplotype associated with natural resistance to HIV-1 infection. Mol Biol Evol 2014; 31:2402-14. [PMID: 24930137 DOI: 10.1093/molbev/msu193] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The protein product of the myxovirus resistance 2 (MX2) gene restricts HIV-1 and simian retroviruses. We demonstrate that MX2 evolved adaptively in mammals with distinct sites representing selection targets in distinct branches; selection mainly involved residues in loop 4, previously shown to carry antiviral determinants. Modeling data indicated that positively selected sites form a continuous surface on loop 4, which folds into two antiparallel α-helices protruding from the stalk domain. A population genetics-phylogenetics approach indicated that the coding region of MX2 mainly evolved under negative selection in the human lineage. Nonetheless, population genetic analyses demonstrated that natural selection operated on MX2 during the recent history of human populations: distinct selective events drove the frequency increase of two haplotypes in the populations of Asian and European ancestry. The Asian haplotype carries a susceptibility allele for melanoma; the European haplotype is tagged by rs2074560, an intronic variant. Analyses performed on three independent European cohorts of HIV-1-exposed seronegative individuals with different geographic origin and distinct exposure route showed that the ancestral (G) allele of rs2074560 protects from HIV-1 infection with a recessive effect (combined P = 1.55 × 10(-4)). The same allele is associated with lower in vitro HIV-1 replication and increases MX2 expression levels in response to IFN-α. Data herein exploit evolutionary information to identify a novel host determinant of HIV-1 infection susceptibility.
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Affiliation(s)
- Manuela Sironi
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini, Italy
| | - Mara Biasin
- Department of Biomedical and Clinical Sciences, University of Milan, Milan, Italy
| | - Rachele Cagliani
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini, Italy
| | - Federica Gnudi
- Department of Biomedical and Clinical Sciences, University of Milan, Milan, Italy
| | - Irma Saulle
- Department of Biomedical and Clinical Sciences, University of Milan, Milan, Italy
| | - Salomè Ibba
- Department of Biomedical and Clinical Sciences, University of Milan, Milan, Italy
| | - Giulia Filippi
- Department of Biotechnology and Biosciences, University of Milan-Bicocca, Milan, Italy
| | - Sarah Yahyaei
- Department of Biomedical and Clinical Sciences, University of Milan, Milan, Italy
| | - Claudia Tresoldi
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini, Italy
| | - Stefania Riva
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini, Italy
| | - Daria Trabattoni
- Department of Biomedical and Clinical Sciences, University of Milan, Milan, Italy
| | - Luca De Gioia
- Department of Biotechnology and Biosciences, University of Milan-Bicocca, Milan, Italy
| | | | | | - Diego Forni
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini, Italy
| | - Chiara Pontremoli
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini, Italy
| | - Juan Antonio Pineda
- Infectious Diseases and Microbiology Clinical Unit, Valme Hospital, Seville, Spain
| | - Uberto Pozzoli
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini, Italy
| | - Antonio Rivero-Juarez
- Maimonides Institut for Biomedical Research (IMIBIC), Reina Sofia Universitary Hospital, University of Cordoba, Cordoba, Spain
| | - Antonio Caruz
- Immunogenetics Unit, Department of Experimental Biology, University of Jaen, Jaen, Spain
| | - Mario Clerici
- Department of Physiopathology and Transplantation, University of Milan, Milan, ItalyDon C. Gnocchi Foundation ONLUS, IRCCS, Milan, Italy
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359
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Transfer of the amino-terminal nuclear envelope targeting domain of human MX2 converts MX1 into an HIV-1 resistance factor. J Virol 2014; 88:9017-26. [PMID: 24899177 DOI: 10.1128/jvi.01269-14] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED The myxovirus resistance 2 (MX2) protein of humans has been identified recently as an interferon (IFN)-inducible inhibitor of human immunodeficiency virus type 1 (HIV-1) that acts at a late postentry step of infection to prevent the nuclear accumulation of viral cDNA (C. Goujon et al., Nature 502:559-562, 2013, http://dx.doi.org/10.1038/nature12542; M. Kane et al., Nature 502:563-566, 2013, http://dx.doi.org/10.1038/nature12653; Z. Liu et al., Cell Host Microbe 14:398-410, 2013, http://dx.doi.org/10.1016/j.chom.2013.08.015). In contrast, the closely related human MX1 protein, which suppresses infection by a range of RNA and DNA viruses (such as influenza A virus [FluAV]), is ineffective against HIV-1. Using a panel of engineered chimeric MX1/2 proteins, we demonstrate that the amino-terminal 91-amino-acid domain of MX2 confers full anti-HIV-1 function when transferred to the amino terminus of MX1, and that this fusion protein retains full anti-FluAV activity. Confocal microscopy experiments further show that this MX1/2 fusion, similar to MX2 but not MX1, can localize to the nuclear envelope (NE), linking HIV-1 inhibition with MX accumulation at the NE. MX proteins are dynamin-like GTPases, and while MX1 antiviral function requires GTPase activity, neither MX2 nor MX1/2 chimeras require this attribute to inhibit HIV-1. This key discrepancy between the characteristics of MX1- and MX2-mediated viral resistance, together with previous observations showing that the L4 loop of the stalk domain of MX1 is a critical determinant of viral substrate specificity, presumably reflect fundamental differences in the mechanisms of antiviral suppression. Accordingly, we propose that further comparative studies of MX proteins will help illuminate the molecular basis and subcellular localization requirements for implementing the noted diversity of virus inhibition by MX proteins. IMPORTANCE Interferon (IFN) elicits an antiviral state in cells through the induction of hundreds of IFN-stimulated genes (ISGs). The human MX2 protein has been identified as a key effector in the suppression of HIV-1 infection by IFN. Here, we describe a molecular genetic approach, using a collection of chimeric MX proteins, to identify protein domains of MX2 that specify HIV-1 inhibition. The amino-terminal 91-amino-acid domain of human MX2 confers HIV-1 suppressor capabilities upon human and mouse MX proteins and also promotes protein accumulation at the nuclear envelope. Therefore, these studies correlate the cellular location of MX proteins with anti-HIV-1 function and help establish a framework for future mechanistic analyses of MX-mediated virus control.
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360
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Autran B, Hamimi C, Katlama C. One Step Closer to HIV Eradication? CURRENT TREATMENT OPTIONS IN INFECTIOUS DISEASES 2014. [DOI: 10.1007/s40506-014-0017-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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361
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Levin D, Schneider WM, Hoffmann HH, Yarden G, Busetto AG, Manor O, Sharma N, Rice CM, Schreiber G. Multifaceted activities of type I interferon are revealed by a receptor antagonist. Sci Signal 2014; 7:ra50. [PMID: 24866020 DOI: 10.1126/scisignal.2004998] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Type I interferons (IFNs), including various IFN-α isoforms and IFN-β, are a family of homologous, multifunctional cytokines. IFNs activate different cellular responses by binding to a common receptor that consists of two subunits, IFNAR1 and IFNAR2. In addition to stimulating antiviral responses, they also inhibit cell proliferation and modulate other immune responses. We characterized various IFNs, including a mutant IFN-α2 (IFN-1ant) that bound tightly to IFNAR2 but had markedly reduced binding to IFNAR1. Whereas IFN-1ant stimulated antiviral activity in a range of cell lines, it failed to elicit immunomodulatory and antiproliferative activities. The antiviral activities of the various IFNs tested depended on a set of IFN-sensitive genes (the "robust" genes) that were controlled by canonical IFN response elements and responded at low concentrations of IFNs. Conversely, these elements were not found in the promoters of genes required for the antiproliferative responses of IFNs (the "tunable" genes). The extent of expression of tunable genes was cell type-specific and correlated with the magnitude of the antiproliferative effects of the various IFNs. Although IFN-1ant induced the expression of robust genes similarly in five different cell lines, its antiviral activity was virus- and cell type-specific. Our findings suggest that IFN-1ant may be a therapeutic candidate for the treatment of specific viral infections without inducing the immunomodulatory and antiproliferative functions of wild-type IFN.
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Affiliation(s)
- Doron Levin
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - William M Schneider
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10065, USA
| | - Hans-Heinrich Hoffmann
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10065, USA
| | - Ganit Yarden
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | - Ohad Manor
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Nanaocha Sharma
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Charles M Rice
- Laboratory of Virology and Infectious Disease, Center for the Study of Hepatitis C, The Rockefeller University, New York, NY 10065, USA
| | - Gideon Schreiber
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
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362
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Aamer HA, Rajakumar P, Nyaundi J, Murphey-Corb M. Resistance to simian immunodeficiency virus low dose rectal challenge is associated with higher constitutive TRIM5α expression in PBMC. Retrovirology 2014; 11:39. [PMID: 24884551 PMCID: PMC4041354 DOI: 10.1186/1742-4690-11-39] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 05/14/2014] [Indexed: 01/09/2023] Open
Abstract
Background At least six host-encoded restriction factors (RFs), APOBEC3G, TRIM5α, tetherin, SAMHD1, schlafen 11, and Mx2 have now been shown to inhibit HIV and/or SIV replication in vitro. To determine their role in vivo in the resistance of macaques to mucosally-acquired SIV, we quantified both pre-exposure (basal) and post-exposure mRNA levels of these RFs, Mx1, and IFNγ in PBMC, lymph nodes, and duodenum of rhesus macaques undergoing weekly low dose rectal exposures to the primary isolate, SIV/DeltaB670. Results Repetitive challenge divided the monkeys into two groups with respect to their susceptibility to infection: highly susceptible (2–3 challenges, 5 monkeys) and poorly susceptible (≥6 challenges, 3 monkeys). Basal RF and Mx1 expression varied among the three tissues examined, with the lowest expression generally detected in duodenal tissues, and the highest observed in PBMC. The one exception was A3G whose basal expression was greatest in lymph nodes. Importantly, significantly higher basal expression of TRIM5α and Mx1 was observed in PBMC of animals more resistant to mucosal infection. Moreover, individual TRIM5α levels were stable throughout a year prior to infection. Post-exposure induction of these genes was also observed after virus appearance in plasma, with elevated levels in PBMC and duodenum transiently occurring 7–10 days post infection. They did not appear to have an effect on control of viremia. Interestingly, minimal to no induction was observed in the resistant animal that became an elite controller. Conclusions These results suggest that constitutively expressed TRIM5α appears to play a greater role in restricting mucosal transmission of SIV than that associated with type I interferon induction following virus entry. Surprisingly, this association was not observed with the other RFs. The higher basal expression of TRIM5α observed in PBMC than in duodenal tissues emphasizes the understated role of the second barrier to systemic infection involving the transport of virus from the mucosal compartment to the blood. Together, these observations provide a strong incentive for a more comprehensive examination of the intrinsic, variable control of constitutive expression of these genes in the sexual transmission of HIV.
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Affiliation(s)
| | | | | | - Michael Murphey-Corb
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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363
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Mouse knockout models for HIV-1 restriction factors. Cell Mol Life Sci 2014; 71:3749-66. [PMID: 24854580 PMCID: PMC4160573 DOI: 10.1007/s00018-014-1646-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/24/2014] [Accepted: 05/05/2014] [Indexed: 12/21/2022]
Abstract
Infection of cells with human immunodeficiency virus 1 (HIV-1) is controlled by restriction factors, host proteins that counteract a variety of steps in the life cycle of this lentivirus. These include SAMHD1, APOBEC3G and tetherin, which block reverse transcription, hypermutate viral DNA and prevent progeny virus release, respectively. These and other HIV-1 restriction factors are conserved and have clear orthologues in the mouse. This review summarises studies in knockout mice lacking HIV-1 restriction factors. In vivo experiments in such animals have not only validated in vitro data obtained from cultured cells, but have also revealed new findings about the biology of these proteins. Indeed, genetic ablation of HIV-1 restriction factors in the mouse has provided evidence that restriction factors control retroviruses and other viruses in vivo and has led to new insights into the mechanisms by which these proteins counteract infection. For example, in vivo experiments in knockout mice demonstrate that virus control exerted by restriction factors can shape adaptive immune responses. Moreover, the availability of animals lacking restriction factors opens the possibility to study the function of these proteins in other contexts such as autoimmunity and cancer. Further in vivo studies of more recently identified HIV-1 restriction factors in gene targeted mice are, therefore, justified.
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364
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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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Saez-Cirion A, Jacquelin B, Barré-Sinoussi F, Müller-Trutwin M. Immune responses during spontaneous control of HIV and AIDS: what is the hope for a cure? Philos Trans R Soc Lond B Biol Sci 2014; 369:20130436. [PMID: 24821922 PMCID: PMC4024229 DOI: 10.1098/rstb.2013.0436] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
HIV research has made rapid progress and led to remarkable achievements in recent decades, the most important of which are combination antiretroviral therapies (cART). However, in the absence of a vaccine, the pandemic continues, and additional strategies are needed. The 'towards an HIV cure' initiative aims to eradicate HIV or at least bring about a lasting remission of infection during which the host can control viral replication in the absence of cART. Cases of spontaneous and treatment-induced control of infection offer substantial hope. Here, we describe the scientific knowledge that is lacking, and the priorities that have been established for research into a cure. We discuss in detail the immunological lessons that can be learned by studying natural human and animal models of protection and spontaneous control of viraemia or of disease progression. In particular, we describe the insights we have gained into the immune mechanisms of virus control, the impact of early virus-host interactions and why chronic inflammation, a hallmark of HIV infection, is an obstacle to a cure. Finally, we enumerate current interventions aimed towards improving the host immune response.
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Affiliation(s)
| | | | | | - M. Müller-Trutwin
- Institut Pasteur, Unité de Régulation des Infections Rétrovirales, Paris, France
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366
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Aydin H, Taylor MW, Lee JE. Structure-guided analysis of the human APOBEC3-HIV restrictome. Structure 2014; 22:668-84. [PMID: 24657093 DOI: 10.1016/j.str.2014.02.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 02/11/2014] [Accepted: 02/20/2014] [Indexed: 01/03/2023]
Abstract
Human APOBEC3 (A3) proteins are host-encoded intrinsic restriction factors that inhibit the replication of many retroviral pathogens. Restriction is believed to occur as a result of the DNA cytosine deaminase activity of the A3 proteins; this activity converts cytosines into uracils in single-stranded DNA retroviral replication intermediates. A3 proteins are also equipped with deamination-independent means to restrict retroviruses that work cooperatively with deamination-dependent restriction pathways. A3 proteins substantially bolster the intrinsic immune system by providing a powerful block to the transmission of retroviral pathogens; however, most retroviruses are able to subvert this replicative restriction in their natural host. HIV-1, for instance, evades A3 proteins through the activity of its accessory protein Vif. Here, we summarize data from recent A3 structural and functional studies to provide perspectives into the interactions between cellular A3 proteins and HIV-1 macromolecules throughout the viral replication cycle.
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Affiliation(s)
- Halil Aydin
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Matthew W Taylor
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Jeffrey E Lee
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada.
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367
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Stevenson M. CROI 2014: Basic science review. TOPICS IN ANTIVIRAL MEDICINE 2014; 22:574-578. [PMID: 24901883 PMCID: PMC6148911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In the HIV basic science categories of the 2014 Conference on Retroviruses and Opportunistic Infections, research examining obstacles to viral eradication continued to be a major component. This research encompassed areas of activity from the identification of where virus resides in individuals on suppressive antiretroviral therapy to studies aimed at eliminating long-lived viral reservoirs that persist in the face of therapy. In the area of antiviral restrictions, a number of presentations highlighted the ability of host factors to profoundly shape the interplay between virus and host and, in particular, how innate immune response opposes viral infection through the induction of antiviral restrictions.
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368
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Maelfait J, Seiradake E, Rehwinkel J. Keeping your armour intact: how HIV-1 evades detection by the innate immune system: HIV-1 capsid controls detection of reverse transcription products by the cytosolic DNA sensor cGAS. Bioessays 2014; 36:649-57. [PMID: 24782340 PMCID: PMC4190646 DOI: 10.1002/bies.201400019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
HIV-1 infects dendritic cells (DCs) without triggering an effective innate antiviral immune response. As a consequence, the induction of adaptive immune responses controlling virus spread is limited. In a recent issue of Immunity, Lahaye and colleagues show that intricate interactions of HIV capsid with the cellular cofactor cyclophilin A (CypA) control infection and innate immune activation in DCs. Manipulation of HIV-1 capsid to increase its affinity for CypA results in reduced virus infectivity and facilitates access of the cytosolic DNA sensor cGAS to reverse transcribed DNA. This in turn induces a strong host response. Here, we discuss these findings in the context of recent developments in innate immunity and consider the implications for disease control and vaccine design.
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Affiliation(s)
- Jonathan Maelfait
- Medical Research Council Human Immunology Unit, Medical Research Council Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
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369
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Abstract
Myxovirus resistance 2 (Mx2/MxB) has recently been uncovered as an effector of the anti-HIV-1 activity of type I interferons (IFNs) that inhibits HIV-1 at an early stage postinfection, after reverse transcription but prior to proviral integration into host DNA. The mechanistic details of Mx2 antiviral activity are not yet understood, but a few substitutions in the HIV-1 capsid have been shown to confer resistance to Mx2. Through a combination of in vitro evolution and unbiased mutagenesis, we further map the determinants of sensitivity to Mx2 and reveal that multiple capsid (CA) surfaces define sensitivity to Mx2. Intriguingly, we reveal an unanticipated sensitivity determinant within the C-terminal domain of capsid. We also report that Mx2s derived from multiple primate species share the capacity to potently inhibit HIV-1, whereas selected nonprimate orthologs have no such activity. Like TRIM5α, another CA targeting antiretroviral protein, primate Mx2s exhibit species-dependent variation in antiviral specificity against at least one extant virus and multiple HIV-1 capsid mutants. Using a combination of chimeric Mx2 proteins and evolution-guided approaches, we reveal that a single residue close to the N terminus that has evolved under positive selection can determine antiviral specificity. Thus, the variable N-terminal region can define the spectrum of viruses inhibited by Mx2. Importance: Type I interferons (IFNs) inhibit the replication of most mammalian viruses. IFN stimulation upregulates hundreds of different IFN-stimulated genes (ISGs), but it is often unclear which ISGs are responsible for inhibition of a given virus. Recently, Mx2 was identified as an ISG that contributes to the inhibition of HIV-1 replication by type I IFN. Thus, Mx2 might inhibit HIV-1 replication in patients, and this inhibitory action might have therapeutic potential. The mechanistic details of how Mx2 inhibits HIV-1 are currently unclear, but the HIV-1 capsid protein is the likely viral target. Here, we determine the regions of capsid that specify sensitivity to Mx2. We demonstrate that Mx2 from multiple primates can inhibit HIV-1, whereas Mx2 from other mammals (dogs and sheep) cannot. We also show that primate variants of Mx2 differ in the spectrum of lentiviruses they inhibit and that a single residue in Mx2 can determine this antiviral specificity.
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370
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Kukkonen S, Martinez-Viedma MDP, Kim N, Manrique M, Aldovini A. HIV-1 Tat second exon limits the extent of Tat-mediated modulation of interferon-stimulated genes in antigen presenting cells. Retrovirology 2014; 11:30. [PMID: 24742347 PMCID: PMC4036831 DOI: 10.1186/1742-4690-11-30] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 03/27/2014] [Indexed: 12/14/2022] Open
Abstract
Background We have shown that HIV-1 Tat interaction with MAP2K3, MAP2K6, and IRF7 promoters is key to IFN-stimulated genes (ISG) activation in immature dendritic cells and macrophages. Results We evaluated how Tat alleles and mutants differ in cellular gene modulation of immature dendritic cells and monocyte-derived macrophages and what similarities this modulation has with that induced by interferons. The tested alleles and mutants modulated to different degrees ISG, without concomitant induction of interferons. The first exon TatSF21-72 and the minimal transactivator TatSF21-58, all modulated genes to a significantly greater extent than full-length wild type, two-exon Tat, indicating that Tat second exon is critical in reducing the innate response triggered by HIV-1 in these cells. Mutants with reduced LTR transactivation had a substantially reduced effect on host gene expression modulation than wild type TatSF2. However, the more potent LTR transactivator TatSF2A58T modulated ISG expression to a lower degree compared to TatSF2. A cellular gene modulation similar to that induced by Tat and Tat mutants in immature dendritic cells could be observed in monocyte-derived macrophages, with the most significant pathways affected by Tat being the same in both cell types. Tat expression in cells deleted of the type I IFN locus or receptor resulted in a gene modulation pattern similar to that induced in primary immature dendritic cells and monocyte-derived macrophages, excluding the involvement of type I IFNs in Tat-mediated gene modulation. ISG activation depends on Tat interaction with MAP2K3, MAP2K6, and IRF7 promoters and a single exon Tat protein more strongly modulated the luciferase activity mediated by MAP2K3, MAP2K6, and IRF7 promoter sequences located 5′ of the RNA start site than the wild type two-exon Tat, while a cysteine and lysine Tat mutants, reduced in LTR transactivation, had negligible effects on these promoters. Chemical inhibition of CDK9 or Sp1 decreased Tat activation of MAP2K3-, MAP2K6-, and IRF7-mediated luciferase transcription. Conclusions Taken together, these data indicate that the second exon of Tat is critical to the containment of the innate response stimulated by Tat in antigen presenting cells and support a role for Tat in stimulating cellular transcription via its interaction with transcription factors present at promoters.
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Affiliation(s)
| | | | | | | | - Anna Aldovini
- Department of Pediatrics, Harvard Medical School, Department of Medicine, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA.
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371
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McCarthy KR, Johnson WE. Plastic proteins and monkey blocks: how lentiviruses evolved to replicate in the presence of primate restriction factors. PLoS Pathog 2014; 10:e1004017. [PMID: 24743473 PMCID: PMC3990706 DOI: 10.1371/journal.ppat.1004017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Kevin R. McCarthy
- Harvard Program in Virology Harvard Medical School, Boston, Massachusetts, United States of America
- Boston College, Biology Department, Chestnut Hill, Massachusetts, United States of America
| | - Welkin E. Johnson
- Boston College, Biology Department, Chestnut Hill, Massachusetts, United States of America
- * E-mail:
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372
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Goujon C. [Human MX2 is an effector of IFN-mediated resistance to HIV-1 infection]. Med Sci (Paris) 2014; 30:233-5. [PMID: 24685207 DOI: 10.1051/medsci/20143003004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Caroline Goujon
- Infectious Diseases Department, King's College London, School of Medicine, 2nd floor Borough Wing, Guy's Hospital, SE1 3LH Londres, Royaume-Uni
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373
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Shah VB, Aiken C. Gene expression analysis of a panel of cell lines that differentially restrict HIV-1 CA mutants infection in a cyclophilin a-dependent manner. PLoS One 2014; 9:e92724. [PMID: 24663101 PMCID: PMC3963944 DOI: 10.1371/journal.pone.0092724] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 02/25/2014] [Indexed: 12/31/2022] Open
Abstract
HIV-1 replication is dependent on binding of the viral capsid to the host protein cyclophilin A (CypA). Interference with cyclophilin A binding, either by mutations in the HIV-1 capsid protein (CA) or by the drug cyclosporine A (CsA), inhibits HIV-1 replication in cell culture. Resistance to CsA is conferred by A92E or G94D substitutions in CA. The mutant viruses are also dependent on CsA for their replication. Interestingly, infection of some cell lines by these mutants is enhanced by CsA, while infection of others is not affected by the drug. The cells are thus termed nonpermissive and permissive, respectively, for infection by CsA-dependent mutants. The mechanistic basis for the cell type dependence is not well understood, but has been hypothesized to result from a dominant-acting host factor that blocks HIV-1 infection by a mechanism that requires CypA binding to the viral capsid. In an effort to identify a CypA-dependent host restriction factor, we adopted a strategy involving comparative gene expression analysis in three permissive and three non-permissive cell types. We ranked the genes based on their relative overexpression in non-permissive cell types compared to the permissive cell types. Based on specific selection criteria, 26 candidate genes were selected and targeted using siRNA in nonpermissive (HeLa) cells. Depletion of none of the selected candidate genes led to the reversal of CsA-dependent phenotype of the A92E mutant. Our data suggest that none of the 26 genes tested is responsible for the dependence of the A92E mutant on CsA. Our study provides gene expression data that may be useful for future efforts to identify the putative CypA-dependent HIV-1 restriction factor and in studies of other cell-specific phenotypes.
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Affiliation(s)
- Vaibhav B. Shah
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Christopher Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- * E-mail:
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374
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Ferreira VH, Kafka JK, Kaushic C. Influence of common mucosal co-factors on HIV infection in the female genital tract. Am J Reprod Immunol 2014; 71:543-54. [PMID: 24617528 DOI: 10.1111/aji.12221] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 01/28/2014] [Indexed: 12/14/2022] Open
Abstract
Women constitute almost half of HIV-infected population globally, and the female genital tract (FGT) accounts for approximately 40% of all new HIV infections worldwide. The FGT is composed of upper and lower parts, distinct in their morphological and functional characteristics. Co-factors in the genital microenvironment, such as presence of hormones, semen, and other sexually transmitted infections, can facilitate or deter HIV infection and play a critical role in determining susceptibility to HIV. In this review, we examine some of these co-factors and their potential influence. Presence of physical and chemical barriers such as epithelial tight junctions, mucus, and anti-microbial peptides can actively block and inhibit viral replication, presenting a significant deterrent to HIV. Upon exposure, HIV and other pathogens first encounter the genital epithelium: cells that express a wide repertoire of pattern recognition receptors that can recognize and directly initiate innate immune responses. These and other interactions in the genital tract can lead to direct and indirect inflammation and enhance the number of local target cells, immune activation, and microbial translocation, all of which promote HIV infection and replication. Better understanding of the dynamics of HIV transmission in the female genital tract would be invaluable for improving the design of prophylactic strategies against HIV.
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Affiliation(s)
- Victor H Ferreira
- Department of Pathology and Molecular Medicine, McMaster Immunology Research Centre, Michael G. DeGroote Institute of Infectious Diseases Research, McMaster University, Hamilton, ON, Canada
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375
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Tsai L, Tasovski I, Leda AR, Chin MPS, Cheng-Mayer C. The number and genetic relatedness of transmitted/founder virus impact clinical outcome in vaginal R5 SHIVSF162P3N infection. Retrovirology 2014; 11:22. [PMID: 24612462 PMCID: PMC3975242 DOI: 10.1186/1742-4690-11-22] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 02/23/2014] [Indexed: 12/31/2022] Open
Abstract
Background Severe genetic bottleneck occurs during HIV-1 sexual transmission whereby most infections are initiated by a single transmitted/founder (T/F) virus. Similar observations had been made in nonhuman primates exposed mucosally to SIV/SHIV. We previously reported variable clinical outcome in rhesus macaques inoculated intravaginally (ivg) with a high dose of R5 SHIVSF162P3N. Given the potential contributions of viral diversity to HIV-1 persistence and AIDS pathogenesis and recombination between retroviral genomes increases the genetic diversity, we tested the hypothesis that transmission of multiple variants contributes to heightened levels of virus replication and faster disease progression in the SHIVSF162P3N ivg-infected monkeys. Results We found that the differences in viral replication and disease progression between the transiently viremic (TV; n = 2), chronically-infected (CP; n = 8) and rapid progressor (RP; n = 4) ivg-infected macaques cannot be explained by which variant in the inoculum was infecting the animal. Rather, transmission of a single variant was observed in both TV rhesus, with 1–2 T/F viruses found in the CPs and 2–4 in all four RP macaques. Moreover, the genetic relatedness of the T/F viruses in the CP monkeys with multivariant transmission was greater than that seen in the RPs. Biological characterization of a subset of T/F envelopes from chronic and rapid progressors revealed differences in their ability to mediate entry into monocyte-derived macrophages, with enhanced macrophage tropism observed in the former as compared to the latter. Conclusion Our study supports the tenet that sequence diversity of the infecting virus contributes to higher steady-state levels of HIV-1 virus replication and faster disease progression and highlights the role of macrophage tropism in HIV-1 transmission and persistence.
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Affiliation(s)
| | | | | | | | - Cecilia Cheng-Mayer
- Aaron Diamond AIDS Research Center, Aaron Diamond Professor at the Rockefeller University, New York, NY, USA.
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376
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Cha L, Berry CM, Nolan D, Castley A, Fernandez S, French MA. Interferon-alpha, immune activation and immune dysfunction in treated HIV infection. Clin Transl Immunology 2014; 3:e10. [PMID: 25505958 PMCID: PMC4232062 DOI: 10.1038/cti.2014.1] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 12/31/2013] [Accepted: 01/01/2014] [Indexed: 02/06/2023] Open
Abstract
Type I interferons (IFNs) exert anti-viral effects through the induction of numerous IFN-stimulated genes and an immunomodulatory effect on innate and adaptive immune responses. This is beneficial in controlling virus infections but prolonged IFN-α activity in persistent virus infections, such as HIV infection, may contribute to immune activation and have a detrimental effect on the function of monocytes and T and B lymphocytes. Activation of monocytes, associated with increased IFN-α activity, contributes to atherosclerotic vascular disease, brain disease and other ‘age-related diseases' in HIV patients treated with long-term antiretroviral therapy (ART). In HIV patients receiving ART, the anti-viral effects of IFN-α therapy have the potential to contribute to eradication of HIV infection while IFN-α inhibitor therapy is under investigation for the treatment of immune activation. The management of HIV patients receiving ART will be improved by understanding more about the opposing effects of IFN-α on HIV infection and disease and by developing methods to assess IFN-α activity in clinical practice.
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Affiliation(s)
- Lilian Cha
- School of Pathology and Laboratory Medicine, University of Western Australia , Crawley, Western Australia, Australia
| | - Cassandra M Berry
- School of Veterinary and Life Sciences, Murdoch University , Murdoch, Western Australia, Australia
| | - David Nolan
- Department of Clinical Immunology and Pathwest Laboratory Medicine, Royal Perth Hospital , Perth, Western Australia, Australia
| | - Allison Castley
- School of Veterinary and Life Sciences, Murdoch University , Murdoch, Western Australia, Australia ; Department of Clinical Immunology and Pathwest Laboratory Medicine, Royal Perth Hospital , Perth, Western Australia, Australia
| | - Sonia Fernandez
- School of Pathology and Laboratory Medicine, University of Western Australia , Crawley, Western Australia, Australia
| | - Martyn A French
- School of Pathology and Laboratory Medicine, University of Western Australia , Crawley, Western Australia, Australia ; Department of Clinical Immunology and Pathwest Laboratory Medicine, Royal Perth Hospital , Perth, Western Australia, Australia
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377
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Dendritic cell-lymphocyte cross talk downregulates host restriction factor SAMHD1 and stimulates HIV-1 replication in dendritic cells. J Virol 2014; 88:5109-21. [PMID: 24574390 DOI: 10.1128/jvi.03057-13] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
UNLABELLED Human immunodeficiency virus type 1 (HIV-1) replication in dendritic cells (DCs) is restricted by SAMHD1. This factor is counteracted by the viral protein Vpx; Vpx is found in HIV-2 and simian immunodeficiency virus (SIV) from sooty mangabeys (SIVsm) or from macaques (SIVmac) but is absent from HIV-1. We previously observed that HIV-1 replication in immature DCs is stimulated by cocultivation with primary T and B lymphocytes, suggesting that HIV-1 restriction in DCs may be overcome under coculture conditions. Here, we aimed to decipher the mechanism of SAMHD1-mediated restriction in DC-lymphocyte coculture. We found that coculture with lymphocytes downregulated SAMHD1 expression and was associated with increased HIV-1 replication in DCs. Moreover, in infected DC-T lymphocyte cocultures, DCs acquired maturation status and secreted type 1 interferon (alpha interferon [IFN-α]). The blockade of DC-lymphocyte cross talk by anti-ICAM-1 antibody markedly inhibited the stimulation of HIV-1 replication and prevented the downregulation of SAMHD1 expression in cocultured DCs. These results demonstrate that, in contrast to purified DCs, cross talk with lymphocytes downregulates SAMHD1 expression in DCs, triggering HIV-1 replication and an antiviral immune response. Therefore, HIV-1 replication and immune sensing by DCs should be investigated in more physiologically relevant models of DC/lymphocyte coculture. IMPORTANCE SAMHD1 restricts HIV-1 replication in dendritic cells (DCs). Here, we demonstrate that, in a coculture model of DCs and lymphocytes mimicking early mucosal HIV-1 infection, stimulation of HIV-1 replication in DCs is associated with downregulation of SAMHD1 expression and activation of innate immune sensing by DCs. We propose that DC-lymphocyte cross talk occurring in vivo modulates host restriction factor SAMHD1, promoting HIV-1 replication in cellular reservoirs and stimulating immune sensing.
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378
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Nuclear trafficking of the HIV-1 pre-integration complex depends on the ADAM10 intracellular domain. Virology 2014; 454-455:60-6. [PMID: 24725932 DOI: 10.1016/j.virol.2014.02.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 11/06/2013] [Accepted: 02/06/2014] [Indexed: 12/25/2022]
Abstract
Previously, we showed that ADAM10 is necessary for HIV-1 replication in primary human macrophages and immortalized cell lines. Silencing ADAM10 expression interrupted the HIV-1 life cycle prior to nuclear translocation of viral cDNA. Furthermore, our data indicated that HIV-1 replication depends on the expression of ADAM15 and γ-secretase, which proteolytically processes ADAM10. Silencing ADAM15 or γ-secretase expression inhibits HIV-1 replication between reverse transcription and nuclear entry. Here, we show that ADAM10 expression also supports replication in CD4(+) T lymphocytes. The intracellular domain (ICD) of ADAM10 associates with the HIV-1 pre-integration complex (PIC) in the cytoplasm and immunoprecipitates and co-localizes with HIV-1 integrase, a key component of PIC. Taken together, our data support a model whereby ADAM15/γ-secretase processing of ADAM10 releases the ICD, which then incorporates into HIV-1 PIC to facilitate nuclear trafficking. Thus, these studies suggest ADAM10 as a novel therapeutic target for inhibiting HIV-1 prior to nuclear entry.
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379
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Ambrose Z, Aiken C. HIV-1 uncoating: connection to nuclear entry and regulation by host proteins. Virology 2014; 454-455:371-9. [PMID: 24559861 DOI: 10.1016/j.virol.2014.02.004] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 12/27/2013] [Accepted: 02/04/2014] [Indexed: 11/25/2022]
Abstract
The RNA genome of human immunodeficiency virus type 1 (HIV-1) is enclosed by a capsid shell that dissociates within the cell in a multistep process known as uncoating, which influences completion of reverse transcription of the viral genome. Double-stranded viral DNA is imported into the nucleus for integration into the host genome, a hallmark of retroviral infection. Reverse transcription, nuclear entry, and integration are coordinated by a capsid uncoating process that is regulated by cellular proteins. Although uncoating is not well understood, recent studies have revealed insights into the process, particularly with respect to nuclear import pathways and protection of the viral genome from DNA sensors. Understanding uncoating will be valuable toward developing novel antiretroviral therapies for HIV-infected individuals.
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Affiliation(s)
- Zandrea Ambrose
- Division of Infectious Diseases, Department of Medicine, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15261, USA.
| | - Christopher Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, School of Medicine, Nashville, TN 37232, USA
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380
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Abstract
Interferon-stimulated gene (ISG) products take on a number of diverse roles. Collectively, they are highly effective at resisting and controlling pathogens. In this review, we begin by introducing interferon (IFN) and the JAK-STAT signaling pathway to highlight features that impact ISG production. Next, we describe ways in which ISGs both enhance innate pathogen-sensing capabilities and negatively regulate signaling through the JAK-STAT pathway. Several ISGs that directly inhibit virus infection are described with an emphasis on those that impact early and late stages of the virus life cycle. Finally, we describe ongoing efforts to identify and characterize antiviral ISGs, and we provide a forward-looking perspective on the ISG landscape.
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Affiliation(s)
- William M. Schneider
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065
| | | | - Charles M. Rice
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY 10065
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381
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De Iaco A, Luban J. Cyclophilin A promotes HIV-1 reverse transcription but its effect on transduction correlates best with its effect on nuclear entry of viral cDNA. Retrovirology 2014; 11:11. [PMID: 24479545 PMCID: PMC3916700 DOI: 10.1186/1742-4690-11-11] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 01/27/2014] [Indexed: 01/13/2023] Open
Abstract
Background The human peptidyl-prolyl isomerase Cyclophilin A (CypA) binds HIV-1 capsid (CA) and influences early steps in the HIV-1 replication cycle. The mechanism by which CypA regulates HIV-1 transduction efficiency is unknown. Disruption of CypA binding to CA, either by genetic means or by the competitive inhibitor cyclosporine A (CsA), reduces the efficiency of HIV-1 transduction in some cells but not in others. Transduction of certain cell types increases significantly when CypA binding to particular HIV-1 CA mutants, i.e., A92E, is prevented. Previous studies have suggested that this cell type-specific effect is due to a dominant-acting, CypA-dependent restriction factor. Results Here we investigated the mechanism by which CypA regulates HIV-1 transduction efficiency using 27 different human cell lines, 32 HeLa subclones, and several previously characterized HIV-1 CA mutants. Disruption of CypA binding to wild-type CA, or to any of the mutant CAs, caused a decrease in HIV-1 reverse transcription in all the cell lines analyzed here. This block to reverse transcription, though, did not correlate with cell type-specific effects on transduction efficiency. The level of 2-LTR circles, a marker for nuclear transport of the viral cDNA that results from reverse transcription, correlated closely with effects on infectivity. No correlation was observed between the cell type-specific effects on infectivity and the steady-state CypA protein levels in these cells. Instead, as indicated by a fate-of-capsid assay, CsA released the HIV-1 CA core from an apparent state of hyperstabilization, in a cell type-specific manner. Conclusion These data demonstrate that, while CypA promotes reverse transcription under all conditions tested here, its effect on HIV-1 infectivity correlates more closely with effects on nuclear entry of the viral cDNA. The data also support the hypothesis that a cell-type specific CypA-dependent restriction factor blocks HIV-1 replication by delaying CA core uncoating and hindering nuclear entry.
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Affiliation(s)
| | - Jeremy Luban
- Department of Microbiology and Molecular Medicine, University of Geneva, Geneva 1211, Switzerland.
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382
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Patzina C, Haller O, Kochs G. Structural requirements for the antiviral activity of the human MxA protein against Thogoto and influenza A virus. J Biol Chem 2014; 289:6020-7. [PMID: 24448803 DOI: 10.1074/jbc.m113.543892] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The interferon-induced dynamin-like MxA protein has broad antiviral activity against many viruses, including orthomyxoviruses such as influenza A and Thogoto virus and bunyaviruses such as La Crosse virus. MxA consists of an N-terminal globular GTPase domain, a connecting bundle signaling element, and the C-terminal stalk that mediates oligomerization and antiviral specificity. We previously reported that the disordered loop L4 that protrudes from the compact stalk is a key determinant of antiviral specificity against influenza A and Thogoto virus. However, the role of individual amino acids for viral target recognition remained largely undefined. By mutational analyses, we identified two regions in the C-terminal part of L4 that contribute to an antiviral interface. Mutations in the proximal motif, at positions 561 and 562, abolished antiviral activity against orthomyxoviruses but not bunyaviruses. In contrast, mutations in the distal motif, around position 577, abolished antiviral activity against both viruses. These results indicate that at least two structural elements in L4 are responsible for antiviral activity and that the proximal motif determines specificity for orthomyxoviruses, whereas the distal sequence serves a conserved structural function.
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Affiliation(s)
- Corinna Patzina
- From the Institute of Virology, University of Freiburg, 79008 Freiburg, Germany
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383
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Kirmaier A, Krupp A, Johnson WE. Understanding restriction factors and intrinsic immunity: insights and lessons from the primate lentiviruses. Future Virol 2014; 9:483-497. [PMID: 26543491 PMCID: PMC4630824 DOI: 10.2217/fvl.14.25] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Primate lentiviruses include the HIVs, HIV-1 and HIV-2; the SIVs, which are endemic to more than 40 species of nonhuman primates in Africa; and SIVmac, an AIDS-causing pathogen that emerged in US macaque colonies in the 1970s. Because of the worldwide spread of HIV and AIDS, primate lentiviruses have been intensively investigated for more than 30 years. Research on these viruses has played a leading role in the discovery and characterization of intrinsic immunity, and in particular the identification of several antiviral effectors (also known as restriction factors) including APOBEC3G, TRIM5α, BST-2/tetherin and SAMHD1. Comparative studies of the primate lentiviruses and their hosts have proven critical for understanding both the evolutionary significance and biological relevance of intrinsic immunity, and the role intrinsic immunity plays in governing viral host range and interspecies transmission of viruses in nature.
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Affiliation(s)
- Andrea Kirmaier
- Biology Department, Boston College, 550 Higgins Hall, 140 Commonwealth Ave., Chestnut Hill, MA 02467, USA
| | - Annabel Krupp
- Biology Department, Boston College, 550 Higgins Hall, 140 Commonwealth Ave., Chestnut Hill, MA 02467, USA
- Institut für Klinische und Molekulare Virologie, Friedrich-Alexander-Universität, Erlangen-Nuremberg, Schlossgarten 4, 91054 Erlangen, Germany
| | - Welkin E Johnson
- Biology Department, Boston College, 550 Higgins Hall, 140 Commonwealth Ave., Chestnut Hill, MA 02467, USA
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Abstract
Three groups have recently shown in Nature and Cell Host & Microbe that MxB/Mx2 is an interferon‐inducible HIV restriction factor, adding to the innate arsenal of the cell against the virus and paving the way for the possible development of new antiviral strategies.
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Affiliation(s)
- Oliver T Fackler
- Department of Infectious Diseases, University Hospital Heidelberg, Germany
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