1
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Wu Y. HIV Preintegration Transcription and Host Antagonism. Curr HIV Res 2023; 21:160-171. [PMID: 37345240 PMCID: PMC10661980 DOI: 10.2174/1570162x21666230621122637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 05/25/2023] [Accepted: 06/08/2023] [Indexed: 06/23/2023]
Abstract
Retrovirus integration is an obligatory step for the viral life cycle, but large amounts of unintegrated DNA (uDNA) accumulate during retroviral infection. For simple retroviruses, in the absence of integration, viral genomes are epigenetically silenced in host cells. For complex retroviruses such as HIV, preintegration transcription has been found to occur at low levels from a large population of uDNA even in the presence of host epigenetic silencing mechanisms. HIV preintegration transcription has been suggested to be a normal early process of HIV infection that leads to the syntheses of all three classes of viral transcripts: multiply-spliced, singly-spliced, and unspliced genomic RNA; only viral early proteins such as Nef are selectively translated at low levels in blood CD4 T cells and macrophages, the primary targets of HIV. The initiation and persistence of HIV preintegration transcription have been suggested to rely on viral accessory proteins, particularly virion Vpr and de novo Tat generated from uDNA; both proteins have been shown to antagonize host epigenetic silencing of uDNA. In addition, stimulation of latently infected resting T cells and macrophages with cytokines, PKC activator, or histone deacetylase inhibitors has been found to greatly upregulate preintegration transcription, leading to low-level viral production or even replication from uDNA. Functionally, Nef synthesized from preintegration transcription is biologically active in modulating host immune functions, lowering the threshold of T cell activation, and downregulating surface CD4, CXCR4/CCR5, and HMC receptors. The early Tat activity from preintegration transcription antagonizes repressive minichromatin assembled onto uDNA. The study of HIV preintegration transcription is important to understanding virus-host interaction and antagonism, viral persistence, and the mechanism of integrase drug resistance. The application of unintegrated lentiviral vectors for gene therapy also offers a safety advantage for minimizing retroviral vector-mediated insertional mutagenesis.
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Affiliation(s)
- Yuntao Wu
- Center for Infectious Disease Research, George Mason University, Manassas, Virginia, United States
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2
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Richetta C, Tu NQ, Delelis O. Different Pathways Conferring Integrase Strand-Transfer Inhibitors Resistance. Viruses 2022; 14:v14122591. [PMID: 36560595 PMCID: PMC9785060 DOI: 10.3390/v14122591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/17/2022] [Accepted: 11/19/2022] [Indexed: 11/23/2022] Open
Abstract
Integrase Strand Transfer Inhibitors (INSTIs) are currently used as the most effective therapy in the treatment of human immunodeficiency virus (HIV) infections. Raltegravir (RAL) and Elvitegravir (EVG), the first generation of INSTIs used successfully in clinical treatment, are susceptible to the emergence of viral resistance and have a high rate of cross-resistance. To counteract these resistant mutants, second-generation INSTI drugs have been developed: Dolutegravir (DTG), Cabotegravir (CAB), and Bictegravir (BIC). However, HIV is also able to develop resistance mechanisms against the second-generation of INSTIs. This review describes the mode of action of INSTIs and then summarizes and evaluates some typical resistance mutations, such as substitution and insertion mutations. The role of unintegrated viral DNA is also discussed as a new pathway involved in conferring resistance to INSTIs. This allows us to have a more detailed understanding of HIV resistance to these inhibitors, which may contribute to the development of new INSTIs in the future.
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3
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Geis FK, Kelenis DP, Goff SP. Two lymphoid cell lines potently silence unintegrated HIV-1 DNAs. Retrovirology 2022; 19:16. [PMID: 35810297 PMCID: PMC9271240 DOI: 10.1186/s12977-022-00602-7] [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] [Received: 12/08/2021] [Accepted: 05/04/2022] [Indexed: 11/23/2022] Open
Abstract
Mammalian cells mount a variety of defense mechanisms against invading viruses to prevent or reduce infection. One such defense is the transcriptional silencing of incoming viral DNA, including the silencing of unintegrated retroviral DNA in most cells. Here, we report that the lymphoid cell lines K562 and Jurkat cells reveal a dramatically higher efficiency of silencing of viral expression from unintegrated HIV-1 DNAs as compared to HeLa cells. We found K562 cells in particular to exhibit an extreme silencing phenotype. Infection of K562 cells with a non-integrating viral vector encoding a green fluorescent protein reporter resulted in a striking decrease in the number of fluorescence-positive cells and in their mean fluorescence intensity as compared to integration-competent controls, even though the levels of viral DNA in the nucleus were equal or in the case of 2-LTR circles even higher. The silencing in K562 cells was functionally distinctive. Histones loaded on unintegrated HIV-1 DNA in K562 cells revealed high levels of the silencing mark H3K9 trimethylation and low levels of the active mark H3 acetylation, as detected in HeLa cells. But infection of K562 cells resulted in low H3K27 trimethylation levels on unintegrated viral DNA as compared to higher levels in HeLa cells, corresponding to low H3K27 trimethylation levels of silent host globin genes in K562 cells as compared to HeLa cells. Most surprisingly, treatment with the HDAC inhibitor trichostatin A, which led to a highly efficient relief of silencing in HeLa cells, only weakly relieved silencing in K562 cells. In summary, we found that the capacity for silencing viral DNAs differs between cell lines in its extent, and likely in its mechanism.
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Affiliation(s)
- Franziska K Geis
- Department of Biochemistry and Molecular Biophysics, Columbia University Medical Center, New York, NY, USA.,Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY, USA.,Howard Hughes Medical Institute, Columbia University Medical Center, New York, NY, USA
| | - Demetra P Kelenis
- Department of Biochemistry and Molecular Biophysics, Columbia University Medical Center, New York, NY, USA.,Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY, USA
| | - Stephen P Goff
- Department of Biochemistry and Molecular Biophysics, Columbia University Medical Center, New York, NY, USA. .,Department of Microbiology and Immunology, Columbia University Medical Center, New York, NY, USA. .,Howard Hughes Medical Institute, Columbia University Medical Center, New York, NY, USA.
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4
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Meltzer B, Dabbagh D, Guo J, Kashanchi F, Tyagi M, Wu Y. Tat controls transcriptional persistence of unintegrated HIV genome in primary human macrophages. Virology 2018; 518:241-252. [PMID: 29549786 DOI: 10.1016/j.virol.2018.03.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Revised: 03/06/2018] [Accepted: 03/07/2018] [Indexed: 01/31/2023]
Abstract
In HIV infected macrophages, a large population of viral genomes persists as the unintegrated form (uDNA) that is transcriptionally active. However, how this transcriptional activity is controlled remains unclear. In this report, we investigated whether Tat, the viral transactivator of transcription, is involved in uDNA transcription. We demonstrate that de novo Tat activity is generated from uDNA, and this uDNA-derived Tat (uTat) transactivates the uDNA LTR. In addition, uTat is required for the transcriptional persistence of uDNA that is assembled into repressive episomal minichromatin. In the absence of uTat, uDNA minichromatin is gradually silenced, but remains highly inducible by HDAC inhibitors (HDACi). Therefore, functionally, uTat antagonizes uDNA minichromatin repression to maintain persistent viral transcription in macrophages. uTat-mediated viral persistence may establish a viral reservoir in macrophages where uDNA were found to persist.
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Affiliation(s)
- Beatrix Meltzer
- National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, USA
| | - Deemah Dabbagh
- National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, USA
| | - Jia Guo
- National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, USA
| | - Fatah Kashanchi
- Laboratory of Molecular Virology, George Mason University, Manassas, USA
| | - Mudit Tyagi
- National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, USA
| | - Yuntao Wu
- National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, USA.
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5
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Abstract
PURPOSE OF REVIEW Despite the success of antiretroviral therapy in suppressing HIV, life-long therapy is required to avoid HIV reactivation from long-lived viral reservoirs. Currently, there is intense interest in searching for therapeutic interventions that can purge the viral reservoir to achieve complete remission in HIV patients off antiretroviral therapy. The evaluation of such interventions relies on our ability to accurately and precisely measure the true size of the viral reservoir. In this review, we assess the most commonly used HIV reservoir assays, as a clear understanding of the strengths and weaknesses of each is vital for the accurate interpretation of results and for the development of improved assays. RECENT FINDINGS The quantification of intracellular or plasma HIV RNA or DNA levels remains the most commonly used tests for the characterization of the viral reservoir. While cost-effective and high-throughput, these assays are not able to differentiate between replication-competent or defective fractions or quantify the number of infected cells. Viral outgrowth assays provide a lower bound for the fraction of cells that can produce infectious virus, but these assays are laborious, expensive and substantially underestimate the potential reservoir of replication-competent provirus. Newer assays are now available that seek to overcome some of these problems, including full-length proviral sequencing, inducible HIV RNA assays, ultrasensitive p24 assays and murine adoptive transfer techniques. The development and evaluation of strategies for HIV remission rely upon our ability to accurately and precisely quantify the size of the remaining viral reservoir. At this time, all current HIV reservoir assays have drawbacks such that combinations of assays are generally needed to gain a more comprehensive view of the viral reservoir. The development of novel, rapid, high-throughput assays that can sensitively quantify the levels of the replication-competent HIV reservoir is still needed.
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Affiliation(s)
- Radwa R Sharaf
- Brigham and Women's Hospital, Harvard Medical School, 65 Landsdowne St, Rm 421, Cambridge, Boston, MA, 02139, USA
| | - Jonathan Z Li
- Brigham and Women's Hospital, Harvard Medical School, 65 Landsdowne St, Rm 421, Cambridge, Boston, MA, 02139, USA.
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6
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Discovery of Novel Small-Molecule Inhibitors of LIM Domain Kinase for Inhibiting HIV-1. J Virol 2017; 91:JVI.02418-16. [PMID: 28381571 PMCID: PMC5469273 DOI: 10.1128/jvi.02418-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 03/28/2017] [Indexed: 01/22/2023] Open
Abstract
A dynamic actin cytoskeleton is necessary for viral entry, intracellular migration, and virion release. For HIV-1 infection, during entry, the virus triggers early actin activity by hijacking chemokine coreceptor signaling, which activates a host dependency factor, cofilin, and its kinase, the LIM domain kinase (LIMK). Although knockdown of human LIM domain kinase 1 (LIMK1) with short hairpin RNA (shRNA) inhibits HIV infection, no specific small-molecule inhibitor of LIMK has been available. Here, we describe the design and discovery of novel classes of small-molecule inhibitors of LIMK for inhibiting HIV infection. We identified R10015 as a lead compound that blocks LIMK activity by binding to the ATP-binding pocket. R10015 specifically blocks viral DNA synthesis, nuclear migration, and virion release. In addition, R10015 inhibits multiple viruses, including Zaire ebolavirus (EBOV), Rift Valley fever virus (RVFV), Venezuelan equine encephalitis virus (VEEV), and herpes simplex virus 1 (HSV-1), suggesting that LIMK inhibitors could be developed as a new class of broad-spectrum antiviral drugs. IMPORTANCE The actin cytoskeleton is a structure that gives the cell shape and the ability to migrate. Viruses frequently rely on actin dynamics for entry and intracellular migration. In cells, actin dynamics are regulated by kinases, such as the LIM domain kinase (LIMK), which regulates actin activity through phosphorylation of cofilin, an actin-depolymerizing factor. Recent studies have found that LIMK/cofilin are targeted by viruses such as HIV-1 for propelling viral intracellular migration. Although inhibiting LIMK1 expression blocks HIV-1 infection, no highly specific LIMK inhibitor is available. This study describes the design, medicinal synthesis, and discovery of small-molecule LIMK inhibitors for blocking HIV-1 and several other viruses and emphasizes the feasibility of developing LIMK inhibitors as broad-spectrum antiviral drugs.
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7
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Hamid FB, Kim J, Shin CG. Distribution and fate of HIV-1 unintegrated DNA species: a comprehensive update. AIDS Res Ther 2017; 14:9. [PMID: 28209198 PMCID: PMC5314604 DOI: 10.1186/s12981-016-0127-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2016] [Accepted: 12/07/2016] [Indexed: 12/30/2022] Open
Abstract
Reverse transcription of viral RNA and the subsequent integration of reverse transcripts are the classical early events of the HIV-1 life-cycle. Simultaneously, abundant unintegrated DNAs (uDNAs), are formed in cells ubiquitously. The uDNAs either undergo recombination or degradation or persist inactively for long periods in the nucleus as future resources. Among them, 2-LTR circles are considered a dead-end for viral spread. Their contribution to the HIV-1 infection is still poorly understood. Nevertheless, the preintegration transcription of the aberrant DNAs and the consequent alterations of cellular factors have already been reported. Since the major fate of the viral genome is to persist as episomal DNA, precise characterization is required for studying the biology of HIV-1. This review compiles the biochemical and genetic updates on uDNA in the HIV-1 life cycle and could provide direction to further study of their roles in HIV-1 replication and application in HIV-1 pathogenesis.
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8
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Thierry E, Deprez E, Delelis O. Different Pathways Leading to Integrase Inhibitors Resistance. Front Microbiol 2017; 7:2165. [PMID: 28123383 PMCID: PMC5225119 DOI: 10.3389/fmicb.2016.02165] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 12/23/2016] [Indexed: 12/20/2022] Open
Abstract
Integrase strand-transfer inhibitors (INSTIs), such as raltegravir (RAL), elvitegravir, or dolutegravir (DTG), are efficient antiretroviral agents used in HIV treatment in order to inhibit retroviral integration. By contrast to RAL treatments leading to well-identified mutation resistance pathways at the integrase level, recent clinical studies report several cases of patients failing DTG treatment without clearly identified resistance mutation in the integrase gene raising questions for the mechanism behind the resistance. These compounds, by impairing the integration of HIV-1 viral DNA into the host DNA, lead to an accumulation of unintegrated circular viral DNA forms. This viral DNA could be at the origin of the INSTI resistance by two different ways. The first one, sustained by a recent report, involves 2-long terminal repeat circles integration and the second one involves expression of accumulated unintegrated viral DNA leading to a basal production of viral particles maintaining the viral information.
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Affiliation(s)
- Eloïse Thierry
- Laboratoire de Biologie et Pharmacologie Appliquée, CNRS UMR8113, Ecole Normale Supérieure de Cachan, Université Paris-Saclay Cachan, France
| | - Eric Deprez
- Laboratoire de Biologie et Pharmacologie Appliquée, CNRS UMR8113, Ecole Normale Supérieure de Cachan, Université Paris-Saclay Cachan, France
| | - Olivier Delelis
- Laboratoire de Biologie et Pharmacologie Appliquée, CNRS UMR8113, Ecole Normale Supérieure de Cachan, Université Paris-Saclay Cachan, France
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9
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Anderson JL, Mota TM, Evans VA, Kumar N, Rezaei SD, Cheong K, Solomon A, Wightman F, Cameron PU, Lewin SR. Understanding Factors That Modulate the Establishment of HIV Latency in Resting CD4+ T-Cells In Vitro. PLoS One 2016; 11:e0158778. [PMID: 27383184 PMCID: PMC4934909 DOI: 10.1371/journal.pone.0158778] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 06/21/2016] [Indexed: 11/18/2022] Open
Abstract
Developing robust in vitro models of HIV latency is needed to better understand how latency is established, maintained and reversed. In this study, we examined the effects of donor variability, HIV titre and co-receptor usage on establishing HIV latency in vitro using two models of HIV latency. Using the CCL19 model of HIV latency, we found that in up to 50% of donors, CCL19 enhanced latent infection of resting CD4+ T-cells by CXCR4-tropic HIV in the presence of low dose IL-2. Increasing the infectious titre of CXCR4-tropic HIV increased both productive and latent infection of resting CD4+ T-cells. In a different model where myeloid dendritic cells (mDC) were co-cultured with resting CD4+ T-cells, we observed a higher frequency of latently infected cells in vitro than CCL19-treated or unstimulated CD4+ T-cells in the presence of low dose IL-2. In the DC-T-cell model, latency was established with both CCR5- and CXCR4-tropic virus but higher titres of CCR5-tropic virus was required in most donors. The establishment of latency in vitro through direct infection of resting CD4+ T-cells is significantly enhanced by CCL19 and mDC, but the efficiency is dependent on virus titre, co-receptor usage and there is significant donor variability.
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Affiliation(s)
- Jenny L Anderson
- Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Talia M Mota
- Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Vanessa A Evans
- Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Nitasha Kumar
- Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Simin D Rezaei
- Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Karey Cheong
- Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Ajantha Solomon
- Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Fiona Wightman
- Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Paul U Cameron
- Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia.,Department of Infectious Diseases, Monash University and Alfred Hospital, Melbourne, Victoria, Australia
| | - Sharon R Lewin
- Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia.,Department of Infectious Diseases, Monash University and Alfred Hospital, Melbourne, Victoria, Australia
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10
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Chan CN, Trinité B, Lee CS, Mahajan S, Anand A, Wodarz D, Sabbaj S, Bansal A, Goepfert PA, Levy DN. HIV-1 latency and virus production from unintegrated genomes following direct infection of resting CD4 T cells. Retrovirology 2016; 13:1. [PMID: 26728316 PMCID: PMC4700562 DOI: 10.1186/s12977-015-0234-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 12/21/2015] [Indexed: 12/31/2022] Open
Abstract
Background HIV-1 integration is prone to a high rate of failure, resulting in the accumulation of unintegrated viral genomes (uDNA) in vivo and in vitro. uDNA can be transcriptionally active, and circularized uDNA genomes are biochemically stable in non-proliferating cells. Resting, non-proliferating CD4 T cells are prime targets of HIV-1 infection and latently infected resting CD4 T cells are the major barrier to HIV cure. Our prior studies demonstrated that uDNA generates infectious virions when T cell activation follows rather than precedes infection. Results Here, we characterize in primary resting CD4 T cells the dynamics of integrated and unintegrated virus expression, genome persistence and sensitivity to latency reversing agents. Unintegrated HIV-1 was abundant in directly infected resting CD4 T cells. Maximal gene expression from uDNA was delayed compared with integrated HIV-1 and was less toxic, resulting in uDNA enrichment over time relative to integrated proviruses. Inhibiting integration with raltegravir shunted the generation of durable latency from integrated to unintegrated genomes. Latent uDNA was activated to de novo virus production by latency reversing agents that also activated latent integrated proviruses, including PKC activators, histone deacetylase inhibitors and P-TEFb agonists. However, uDNA responses displayed a wider dynamic range, indicating differential regulation of expression relative to integrated proviruses. Similar to what has recently been demonstrated for latent integrated proviruses, one or two applications of latency reversing agents failed to activate all latent unintegrated genomes. Unlike integrated proviruses, uDNA gene expression did not down modulate expression of HLA Class I on resting CD4 T cells. uDNA did, however, efficiently prime infected cells for killing by HIV-1-specific cytotoxic T cells. Conclusions These studies demonstrate that contributions by unintegrated genomes to HIV-1 gene expression, virus production, latency and immune responses are inherent properties of the direct infection of resting CD4 T cells. Experimental models of HIV-1 latency employing directly infected resting CD4 T cells should calibrate the contribution of unintegrated HIV-1. Electronic supplementary material The online version of this article (doi:10.1186/s12977-015-0234-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Chi N Chan
- Department of Basic Science, New York University College of Dentistry, New York, NY, 10010, USA.
| | - Benjamin Trinité
- Department of Basic Science, New York University College of Dentistry, New York, NY, 10010, USA.
| | - Caroline S Lee
- Department of Basic Science, New York University College of Dentistry, New York, NY, 10010, USA.
| | - Saurabh Mahajan
- Department of Basic Science, New York University College of Dentistry, New York, NY, 10010, USA.
| | - Akanksha Anand
- Department of Basic Science, New York University College of Dentistry, New York, NY, 10010, USA.
| | - Dominik Wodarz
- Department of Ecology and Evolutionary Biology, University of California, Irvine, School of Biological, Sciences, Irvine, CA, 92697, USA.
| | - Steffanie Sabbaj
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
| | - Anju Bansal
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
| | - Paul A Goepfert
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
| | - David N Levy
- Department of Basic Science, New York University College of Dentistry, New York, NY, 10010, USA.
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11
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Thierry E, Deprez E, Delelis O. Different Pathways Leading to Integrase Inhibitors Resistance. Front Microbiol 2016. [PMID: 28123383 DOI: 10.3389/fmicb.2016.02165/bibtex] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2023] Open
Abstract
Integrase strand-transfer inhibitors (INSTIs), such as raltegravir (RAL), elvitegravir, or dolutegravir (DTG), are efficient antiretroviral agents used in HIV treatment in order to inhibit retroviral integration. By contrast to RAL treatments leading to well-identified mutation resistance pathways at the integrase level, recent clinical studies report several cases of patients failing DTG treatment without clearly identified resistance mutation in the integrase gene raising questions for the mechanism behind the resistance. These compounds, by impairing the integration of HIV-1 viral DNA into the host DNA, lead to an accumulation of unintegrated circular viral DNA forms. This viral DNA could be at the origin of the INSTI resistance by two different ways. The first one, sustained by a recent report, involves 2-long terminal repeat circles integration and the second one involves expression of accumulated unintegrated viral DNA leading to a basal production of viral particles maintaining the viral information.
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Affiliation(s)
- Eloïse Thierry
- Laboratoire de Biologie et Pharmacologie Appliquée, CNRS UMR8113, Ecole Normale Supérieure de Cachan, Université Paris-Saclay Cachan, France
| | - Eric Deprez
- Laboratoire de Biologie et Pharmacologie Appliquée, CNRS UMR8113, Ecole Normale Supérieure de Cachan, Université Paris-Saclay Cachan, France
| | - Olivier Delelis
- Laboratoire de Biologie et Pharmacologie Appliquée, CNRS UMR8113, Ecole Normale Supérieure de Cachan, Université Paris-Saclay Cachan, France
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12
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A Subset of CD4/CD8 Double-Negative T Cells Expresses HIV Proteins in Patients on Antiretroviral Therapy. J Virol 2015; 90:2165-79. [PMID: 26537682 PMCID: PMC4810694 DOI: 10.1128/jvi.01913-15] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 10/21/2015] [Indexed: 12/21/2022] Open
Abstract
A major goal in HIV eradication research is characterizing the reservoir cells that harbor HIV in the presence of antiretroviral therapy (ART), which reseed viremia after treatment is stopped. In general, it is assumed that the reservoir consists of CD4+ T cells that express no viral proteins. However, recent findings suggest that this may be an overly simplistic view and that the cells that contribute to the reservoir may be a diverse population that includes both CD4+ and CD4− cells. In this study, we directly infected resting CD4+ T cells and used fluorescence-activated cell sorting (FACS) and fiber-optic array scanning technology (FAST) to identify and image cells expressing HIV Gag. We found that Gag expression from integrated proviruses occurred in resting cells that lacked surface CD4, likely resulting from Nef- and Env-mediated receptor internalization. We also extended our approach to detect cells expressing HIV proteins in patients suppressed on ART. We found evidence that rare Gag+ cells persist during ART and that these cells are often negative for CD4. We propose that these double-negative α/β T cells that express HIV protein may be a component of the long-lived reservoir.
IMPORTANCE A reservoir of infected cells persists in HIV-infected patients during antiretroviral therapy (ART) that leads to rebound of virus if treatment is stopped. In this study, we used flow cytometry and cell imaging to characterize protein expression in HIV-infected resting cells. HIV Gag protein can be directly detected in infected resting cells and occurs with simultaneous loss of CD4, consistent with the expression of additional viral proteins, such as Env and Nef. Gag+ CD4− cells can also be detected in suppressed patients, suggesting that a subset of infected cells express proteins during ART. Understanding the regulation of viral protein expression during ART will be key to designing effective strategies to eradicate HIV reservoirs.
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13
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Levin A, Hayouka Z, Friedler A, Loyter A. Nucleocytoplasmic shuttling of HIV-1 integrase is controlled by the viral Rev protein. Nucleus 2014. [DOI: 10.4161/nucl.11300] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
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14
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Rasaiyaah J, Tan CP, Fletcher AJ, Price AJ, Blondeau C, Hilditch L, Jacques DA, Selwood DL, James LC, Noursadeghi M, Towers GJ. HIV-1 evades innate immune recognition through specific cofactor recruitment. Nature 2013; 503:402-405. [PMID: 24196705 PMCID: PMC3928559 DOI: 10.1038/nature12769] [Citation(s) in RCA: 343] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2013] [Accepted: 10/08/2013] [Indexed: 01/15/2023]
Abstract
Human immunodeficiency virus (HIV)-1 is able to replicate in primary human macrophages without stimulating innate immunity despite reverse transcription of genomic RNA into double-stranded DNA, an activity that might be expected to trigger innate pattern recognition receptors. We reasoned that if correctly orchestrated HIV-1 uncoating and nuclear entry is important for evasion of innate sensors then manipulation of specific interactions between HIV-1 capsid and host factors that putatively regulate these processes should trigger pattern recognition receptors and stimulate type 1 interferon (IFN) secretion. Here we show that HIV-1 capsid mutants N74D and P90A, which are impaired for interaction with cofactors cleavage and polyadenylation specificity factor subunit 6 (CPSF6) and cyclophilins (Nup358 and CypA), respectively, cannot replicate in primary human monocyte-derived macrophages because they trigger innate sensors leading to nuclear translocation of NF-κB and IRF3, the production of soluble type 1 IFN and induction of an antiviral state. Depletion of CPSF6 with short hairpin RNA expression allows wild-type virus to trigger innate sensors and IFN production. In each case, suppressed replication is rescued by IFN-receptor blockade, demonstrating a role for IFN in restriction. IFN production is dependent on viral reverse transcription but not integration, indicating that a viral reverse transcription product comprises the HIV-1 pathogen-associated molecular pattern. Finally, we show that we can pharmacologically induce wild-type HIV-1 infection to stimulate IFN secretion and an antiviral state using a non-immunosuppressive cyclosporine analogue. We conclude that HIV-1 has evolved to use CPSF6 and cyclophilins to cloak its replication, allowing evasion of innate immune sensors and induction of a cell-autonomous innate immune response in primary human macrophages.
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Affiliation(s)
- Jane Rasaiyaah
- University College London, Medical Research Council Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 90 Gower St, London WC1E 6BT, United Kingdom
| | - Choon Ping Tan
- University College London, Medical Research Council Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 90 Gower St, London WC1E 6BT, United Kingdom
| | - Adam J. Fletcher
- University College London, Medical Research Council Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 90 Gower St, London WC1E 6BT, United Kingdom
| | - Amanda J. Price
- Protein and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Caroline Blondeau
- University College London, Medical Research Council Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 90 Gower St, London WC1E 6BT, United Kingdom
| | - Laura Hilditch
- University College London, Medical Research Council Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 90 Gower St, London WC1E 6BT, United Kingdom
| | - David A Jacques
- Protein and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - David L Selwood
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | - Leo C James
- Protein and Nucleic Acid Chemistry Division, Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Mahdad Noursadeghi
- University College London, Medical Research Council Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 90 Gower St, London WC1E 6BT, United Kingdom
| | - Greg J Towers
- University College London, Medical Research Council Centre for Medical Molecular Virology, Division of Infection and Immunity, University College London, 90 Gower St, London WC1E 6BT, United Kingdom
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15
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An HIV-1 replication pathway utilizing reverse transcription products that fail to integrate. J Virol 2013; 87:12701-20. [PMID: 24049167 DOI: 10.1128/jvi.01939-13] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Integration is a central event in the replication of retroviruses, yet ≥ 90% of HIV-1 reverse transcripts fail to integrate, resulting in accumulation of unintegrated viral DNA in cells. However, understanding what role, if any, unintegrated viral DNA plays in the natural history of HIV-1 has remained elusive. Unintegrated HIV-1 DNA is reported to possess a limited capacity for gene expression restricted to early gene products and is considered a replicative dead end. Although the majority of peripheral blood CD4(+) T cells are refractory to infection, nonactivated CD4 T cells present in lymphoid and mucosal tissues are major targets for infection. Treatment with cytokine interleukin-2 (IL-2), IL-4, IL-7, or IL-15 renders CD4(+) T cells permissive to HIV-1 infection in the absence of cell activation and proliferation and provides a useful model for infection of resting CD4(+) T cells. We found that infection of cytokine-treated resting CD4(+) T cells in the presence of raltegravir or with integrase active-site mutant HIV-1 yielded de novo virus production following subsequent T cell activation. Infection with integration-competent HIV-1 naturally generated a population of cells generating virus from unintegrated DNA. Latent infection persisted for several weeks and could be activated to virus production by a combination of a histone deacetylase inhibitor and a protein kinase C activator or by T cell activation. HIV-1 Vpr was essential for unintegrated HIV-1 gene expression and de novo virus production in this system. Bypassing integration by this mechanism may allow the preservation of genetic information that otherwise would be lost.
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Quantitative analysis of the time-course of viral DNA forms during the HIV-1 life cycle. Retrovirology 2013; 10:87. [PMID: 23938039 PMCID: PMC3766001 DOI: 10.1186/1742-4690-10-87] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 08/02/2013] [Indexed: 01/06/2023] Open
Abstract
Background HIV-1 DNA is found both integrated in the host chromosome and unintegrated in various forms: linear (DNAL) or circular (1-LTRc, 2-LTRc or products of auto-integration). Here, based on pre-established strategies, we extended and characterized in terms of sensitivity two methodologies for quantifying 1-LTRc and DNAL, respectively, the latter being able to discriminate between unprocessed or 3′-processed DNA. Results Quantifying different types of viral DNA genome individually provides new information about the dynamics of all viral DNA forms and their interplay. For DNAL, we found that the 3′-processing reaction was efficient during the early stage of the replication cycle. Moreover, strand-transfer inhibitors (Dolutegravir, Elvitegravir, Raltegravir) affected 3′-processing differently. The comparisons of 2-LTRc accumulation mediated by either strand-transfer inhibitors or catalytic mutation of integrase indicate that 3′-processing efficiency did not influence the total 2-LTRc accumulation although the nature of the LTR-LTR junction was qualitatively affected. Finally, a significant proportion of 1-LTRc was generated concomitantly with reverse transcription, although most of the 1-LTRc were produced in the nucleus. Conclusions We describe the fate of viral DNA forms during HIV-1 infection. Our study reveals the interplay between various forms of the viral DNA genome, the distribution of which can be affected by mutations and by inhibitors of HIV-1 viral proteins. In the latter case, the quantification of 3′-processed DNA in infected cells can be informative about the mechanisms of future integrase inhibitors directly in the cell context.
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Emeagwali N, Hildreth JEK. Human immunodeficiency virus type 1 Vpu and cellular TASK proteins suppress transcription of unintegrated HIV-1 DNA. Virol J 2012; 9:277. [PMID: 23164059 PMCID: PMC3547713 DOI: 10.1186/1743-422x-9-277] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 10/31/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Unintegrated HIV-1 DNA serves as transcriptionally active templates in HIV-infected cells. Several host factors including NF-κβ enhance HIV-1 transcription. HIV-1 induced NF-κβ activation can be suppressed by viral protein U (Vpu). Interestingly HIV-1 Vpu shares amino acid homology with cellular Twik-related Acid Sensitive K+ (TASK) channel 1 and the proteins physically interact in cultured cells and AIDS lymphoid tissue. Furthermore, the first transmembrane domain of TASK-1 is functionally interchangeable with Vpu and like Vpu enhances HIV-1 release. RESULTS Here we further characterize the role of TASK channels and Vpu in HIV-1 replication. We demonstrate that both TASK channels and Vpu can preferentially inhibit transcription of unintegrated HIV-1 DNA. Interestingly, TASK-1 ion channel function is not required and suppression of HIV-1 transcription by TASK-1 and Vpu was reversed by overexpression of RelA (NF-κβ p65). CONCLUSION TASK proteins and Vpu suppress transcription of unintegrated HIV-1 DNA through an NF-κβ-dependent mechanism. Taken together these findings support a possible physiological role for HIV-1 Vpu and TASK proteins as modulators of transcription of unintegrated HIV-1 DNA genomes.
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Affiliation(s)
- Nkiruka Emeagwali
- Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, TN, 37208, USA
| | - James EK Hildreth
- Department of Molecular and Cellular Biology, College of Biological Sciences, University of California, Davis, One Shields Ave, Davis, CA, 95616, USA
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Benyamini H, Loyter A, Friedler A. A structural model of the HIV-1 Rev-integrase complex: the molecular basis of integrase regulation by Rev. Biochem Biophys Res Commun 2011; 416:252-7. [PMID: 22093836 DOI: 10.1016/j.bbrc.2011.10.116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 10/25/2011] [Indexed: 11/17/2022]
Abstract
The HIV-1 Rev and integrase (IN) proteins control important functions in the viral life cycle. We have recently discovered that the interaction between these proteins results in inhibition of IN enzymatic activity. Peptides derived from the Rev and IN binding interfaces have a profound effect on IN catalytic activity: Peptides derived from Rev inhibit IN, while peptides derived from IN stimulate IN activity by inhibiting the Rev-IN interaction. This inhibition leads to multi integration, genomic instability and specific death of virus-infected cells. Here we used protein docking combined with refinement and energy function ranking to suggest a structural model for the Rev-IN complex. Our results indicate that a Rev monomer binds IN at two sites that match our experimental binding data: (1) IN residues 66-80 and 118-128; (2) IN residues 174-188. According to our model, IN binds Rev and its cellular cofactor, lens epithelium derived growth factor (LEDGF), through overlapping interfaces. This supports previous observations that IN is regulated by a tight interplay between Rev and LEDGF. Rev may bind either the IN dimer or tetramer. Accordingly, Rev is suggested to inhibit IN by two possible mechanisms: (i) shifting the oligomerization equilibrium of IN from an active dimer to an inactive tetramer; (ii) displacing LEDGF from IN, resulting in inhibition of IN binding to the viral DNA. Our model is expected to contribute to the development of lead compounds that inhibit the Rev-IN interaction and thus lead to multi-integration of viral cDNA and consequently to apoptosis of HIV-1 infected cells.
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Affiliation(s)
- Hadar Benyamini
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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19
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Sloan RD, Wainberg MA. The role of unintegrated DNA in HIV infection. Retrovirology 2011; 8:52. [PMID: 21722380 PMCID: PMC3148978 DOI: 10.1186/1742-4690-8-52] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 07/01/2011] [Indexed: 01/09/2023] Open
Abstract
Integration of the reverse transcribed viral genome into host chromatin is the hallmark of retroviral replication. Yet, during natural HIV infection, various unintegrated viral DNA forms exist in abundance. Though linear viral cDNA is the precursor to an integrated provirus, increasing evidence suggests that transcription and translation of unintegrated DNAs prior to integration may aid productive infection through the expression of early viral genes. Additionally, unintegrated DNA has the capacity to result in preintegration latency, or to be rescued and yield productive infection and so unintegrated DNA, in some circumstances, may be considered to be a viral reservoir. Recently, there has been interest in further defining the role and function of unintegrated viral DNAs, in part because the use of anti-HIV integrase inhibitors leads to an abundance of unintegrated DNA, but also because of the potential use of non-integrating lentiviral vectors in gene therapy and vaccines. There is now increased understanding that unintegrated viral DNA can either arise from, or be degraded through, interactions with host DNA repair enzymes that may represent a form of host antiviral defence. This review focuses on the role of unintegrated DNA in HIV infection and additionally considers the potential implications for antiviral therapy.
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Affiliation(s)
- Richard D Sloan
- McGill University AIDS Centre, Lady Davis Institute, Jewish General Hospital, Montréal, QC, Canada
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20
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Sloan RD, Kuhl BD, Donahue DA, Roland A, Bar-Magen T, Wainberg MA. Transcription of preintegrated HIV-1 cDNA modulates cell surface expression of major histocompatibility complex class I via Nef. J Virol 2011; 85:2828-36. [PMID: 21209113 PMCID: PMC3067938 DOI: 10.1128/jvi.01854-10] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2010] [Accepted: 12/23/2010] [Indexed: 12/25/2022] Open
Abstract
Although transcription from unintegrated human immunodeficiency virus type 1 (HIV-1) DNA can occur inside infected cells, yielding all classes of viral mRNA transcripts, the translation of viral proteins is very limited. One of the proteins made is Nef, but it is unclear whether Nef produced in this way is able to play a role in immune evasion as occurs with integrated virus. We therefore asked whether transcription from preintegrated HIV-1 cDNAs could result in Nef-mediated modulation of cell surface major histocompatibility complex class I (MHC-I) expression. We infected a Rev-CEM green fluorescent protein (GFP) reporter cell line with virus and blocked integration though use of either an inactive integrase or the integrase inhibitor raltegravir. Infected cells were assayed by flow cytometry for cell surface expression of the HLA-A, HLA-B, and HLA-C allotypes (HLA-ABC), HLA-A31, and HLA-E. Viral RNA and DNA products were assayed via quantitative PCR (qPCR). The prevention of integration had no effect, relative to productively infected cells, on levels of expression of multiply spliced viral mRNA transcripts and Nef protein. Downregulation of HLA-ABC and HLA-A31 also occurred at levels similar to those seen in cells in which integration had occurred. Parallel experiments assaying cell surface HLA-ABC expression in infected activated primary CD4(+) T cells produced a similar pattern of results. Hence, the capacity of HIV-1 to modulate MHC-I is not linked to its ability to integrate. Thus, Nef-mediated evasion of host immune responsiveness might be attributable, in part at least, to transcription from unintegrated viral DNA.
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Affiliation(s)
- Richard D. Sloan
- McGill University AIDS Centre, Lady Davis Institute, Jewish General Hospital, Montréal, Québec, Canada, Department of Experimental Medicine, McGill University, Montréal, Québec, Canada, Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada
| | - Björn D. Kuhl
- McGill University AIDS Centre, Lady Davis Institute, Jewish General Hospital, Montréal, Québec, Canada, Department of Experimental Medicine, McGill University, Montréal, Québec, Canada, Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada
| | - Daniel A. Donahue
- McGill University AIDS Centre, Lady Davis Institute, Jewish General Hospital, Montréal, Québec, Canada, Department of Experimental Medicine, McGill University, Montréal, Québec, Canada, Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada
| | - André Roland
- McGill University AIDS Centre, Lady Davis Institute, Jewish General Hospital, Montréal, Québec, Canada, Department of Experimental Medicine, McGill University, Montréal, Québec, Canada, Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada
| | - Tamara Bar-Magen
- McGill University AIDS Centre, Lady Davis Institute, Jewish General Hospital, Montréal, Québec, Canada, Department of Experimental Medicine, McGill University, Montréal, Québec, Canada, Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada
| | - Mark A. Wainberg
- McGill University AIDS Centre, Lady Davis Institute, Jewish General Hospital, Montréal, Québec, Canada, Department of Experimental Medicine, McGill University, Montréal, Québec, Canada, Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada
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Levin A, Hayouka Z, Friedler A, Loyter A. Peptides derived from the HIV-1 integrase promote HIV-1 infection and multi-integration of viral cDNA in LEDGF/p75-knockdown cells. Virol J 2010; 7:177. [PMID: 20678206 PMCID: PMC2924314 DOI: 10.1186/1743-422x-7-177] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Accepted: 08/02/2010] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The presence of the cellular Lens Epithelium Derived Growth Factor p75 (LEDGF/p75) protein is essential for integration of the Human immunodeficiency virus type 1 (HIV-1) cDNA and for efficient virus production. In the absence of LEDGF/p75 very little integration and virus production can be detected, as was demonstrated using LEDGF/p75-knockdown cells. RESULTS Here we show that the failure to infect LEDGF/p75-knockdown cells has another reason aside from the lack of LEDGF/p75. It is also due to inhibition of the viral integrase (IN) enzymatic activity by an early expressed viral Rev protein. The formation of an inhibitory Rev-IN complex in virus-infected cells can be disrupted by the addition of three IN-derived, cell-permeable peptides, designated INr (IN derived-Rev interacting peptides) and INS (IN derived-integrase stimulatory peptide). The results of the present work confirm previous results showing that HIV-1 fails to infect LEDGF/p75-knockdown cells. However, in the presence of INrs and INS peptides, relatively high levels of viral cDNA integration as well as productive virus infection were obtained following infection by a wild type (WT) HIV-1 of LEDGF/p75-knockdown cells. CONCLUSIONS It appears that the lack of integration observed in HIV-1 infected LEDGF/p75-knockdown cells is due mainly to the inhibitory effect of Rev following the formation of a Rev-IN complex. Disruption of this inhibitory complex leads to productive infection in those cells.
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Affiliation(s)
- Aviad Levin
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences; The Hebrew University of Jerusalem, Safra Campus, Givat Ram, Jerusalem 91904, Israel
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22
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Sloan RD, Donahue DA, Kuhl BD, Bar-Magen T, Wainberg MA. Expression of Nef from unintegrated HIV-1 DNA downregulates cell surface CXCR4 and CCR5 on T-lymphocytes. Retrovirology 2010; 7:44. [PMID: 20465832 PMCID: PMC2881062 DOI: 10.1186/1742-4690-7-44] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Accepted: 05/13/2010] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Transcription of HIV-1 cDNA prior to, or in the absence of, integration leads to synthesis of all classes of viral RNA transcripts. Yet only a limited range of viral proteins, including Nef, are translated in this context. Nef expression from unintegrated HIV-1 DNA has been shown to reduce cell surface CD4 levels in T-cells. We wished to determine whether Nef expressed from unintegrated DNA was also able to downregulate the chemokine coreceptors CXCR4 and CCR5.Viral integration was blocked through use of an inactive integrase or by using the integrase inhibitor raltegravir. Infected cells bearing unintegrated DNA were assayed by flow cytometry in the GFP reporter cell line, Rev-CEM, for cell surface levels of CD4, CXCR4 and CCR5. RESULTS In cells bearing only unintegrated HIV-1 DNA, we found that surface levels of CXCR4 were significantly reduced, while levels of CCR5 were also diminished, but not to the extent of CXCR4. We also confirmed the downregulation of CD4. Similar patterns of results were obtained with both integrase-deficient virus or with wild-type infections of cells treated with raltegravir. The Alu-HIV qPCR assay that we used for detection of proviral DNA did not detect any integrated viral DNA. CONCLUSIONS Our results demonstrate that Nef can be expressed from unintegrated DNA at functionally relevant levels and suggest a role for Nef in downregulation of CXCR4 and CCR5. These findings may help to explain how downregulation of CXCR4, CCR5 and CD4 might restrict superinfection and/or prevent signal transduction involving HIV-1 infected cells.
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Affiliation(s)
- Richard D Sloan
- McGill University AIDS Centre, Lady Davis Institute, Jewish General Hospital, Montréal, QC, Canada
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23
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Development of a nonintegrating Rev-dependent lentiviral vector carrying diphtheria toxin A chain and human TRAF6 to target HIV reservoirs. Gene Ther 2010; 17:1063-76. [PMID: 20410930 PMCID: PMC2910233 DOI: 10.1038/gt.2010.53] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Persistence of HIV despite highly active antiretroviral therapy (HAART) is a lasting challenge to virus eradication. To develop a strategy complementary to HAART, we constructed a series of Rev-dependent lentiviral vectors carrying diphtheria toxin A chain (DT-A) and its attenuated mutants, as well as human TRAF6. Expression of these suicide genes following delivery through viral particles is dependent on Rev, which exists only in infected cells. Among these toxins, DT-A has been known to trigger cell death with as little as a single molecule, whereas two of the attenuated mutants in this study, DT-A(176) and DT-A(ΔN), were well-tolerated by cells at low levels. TRAF6 induced apoptosis only with persistent overexpression. Thus, these suicide genes, which induce cell death at different expression levels, offer a balance between efficacy and safety. To minimize possible mutagenesis introduced by retroviral integration in non-target cells, we further developed a non-integrating Rev-dependent (NIRD) lentiviral vector to deliver these genes. In addition, we constructed a DT-A-resistant human cell line by introducing a human elongation factor 2 (EF-2) mutant into HEK293T cells. This allowed us to manufacture the first high-titer NIRD lentiviral particles carrying DT-A to target HIV-positive cells.
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Levin A, Hayouka Z, Friedler A, Loyter A. Nucleocytoplasmic shuttling of HIV-1 integrase is controlled by the viral Rev protein. Nucleus 2010; 1:190-201. [PMID: 21326951 PMCID: PMC3030695 DOI: 10.4161/nucl.1.2.11300] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 01/13/2010] [Accepted: 01/14/2010] [Indexed: 01/21/2023] Open
Abstract
In the current study we show that the Rev protein of Human Immunodeficiency Virus type 1 (HIV-1) inhibits nuclear import and mediates nuclear export of the HIV-1 integrase (IN) protein, which catalyzes integration of the viral cDNA. Interaction between IN and Rev in virus infected cells, resulting in the formation of a Rev-IN complex, has been previously described by us. Here we show that nuclear import of the IN, is inhibited by early expressed Rev. No nuclear import of IN was observed when Rev-overexpressing cells were infected by wild-type HIV-1. Similarly, no translocation of IN into nuclei was observed in the presence of Rev-derived peptides. On the other hand, massive nuclear import was observed following infection by a ΔRev virus or in the presence of peptides that promote dissociation of the Rev-IN complex. Our results show that IN is only transiently present within the nuclei of infected cells. Treatment of infected cells with leptomycin B caused nuclear retention of the Rev-IN complex. Removal of the leptomycin from these treated cells resulted in nuclear export of both Rev and IN. On the other hand, disruption of the nuclear located Rev-IN complex resulted in export of only the Rev protein indicating Rev-mediated nuclear export of IN. Our results suggest the involvement of Rev in regulating the integration process by limiting the number of integration events per cell despite the presence of numerous copies of viral cDNA.
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Affiliation(s)
- Aviad Levin
- Department of Biological Chemistry; The Alexander Silberman Institute of Life Sciences
| | - Zvi Hayouka
- Institute of Chemistry; The Hebrew University of Jerusalem; Jerusalem, Israel
| | - Assaf Friedler
- Institute of Chemistry; The Hebrew University of Jerusalem; Jerusalem, Israel
| | - Abraham Loyter
- Department of Biological Chemistry; The Alexander Silberman Institute of Life Sciences
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25
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Levin A, Hayouka Z, Friedler A, Brack-Werner R, Volsky DJ, Loyter A. A novel role for the viral Rev protein in promoting resistance to superinfection by human immunodeficiency virus type 1. J Gen Virol 2010; 91:1503-13. [PMID: 20147519 DOI: 10.1099/vir.0.019760-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
At the cellular level, cells infected with human immunodeficiency virus type 1 (HIV-1) exhibit immunity to a second infection by the virus that initiated the first infection or by related viruses [superinfection resistance (SIR)]. In the case of HIV infection, SIR was basically attributed to downregulation of the CD4 receptors. We have recently reported on an interaction between HIV-1 Rev and integrase (IN) proteins, which results in inhibition of IN activity in vitro and integration of cDNA in HIV-1-infected cells. A novel function for the viral Rev protein in controlling integration of HIV cDNAs was thus proposed. The results of the present work suggest involvement of the inhibitory Rev in sustaining SIR. A single exposure to wild-type HIV-1 resulted in one to two integrations per cell. The number of integrated proviral cDNA copies remained at this low level even after double infection or superinfection. SIR was dependent on Rev expression by the strain used for the first infection and was eliminated by peptides that disrupt intracellular complex formation between IN and Rev. The same lack of resistance was observed in the absence of Rev, namely following first infection with a DeltaRev HIV strain. The involvement of Rev, expressed from either unintegrated or integrated viral cDNA, in promoting SIR was clearly demonstrated. We conclude that SIR involves Rev-dependent control of HIV cDNA integration.
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Affiliation(s)
- Aviad Levin
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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26
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Retroviral integration site selection. Viruses 2010; 2:111-130. [PMID: 21994603 PMCID: PMC3185549 DOI: 10.3390/v2010111] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2009] [Revised: 12/21/2009] [Accepted: 01/05/2010] [Indexed: 02/07/2023] Open
Abstract
The stable insertion of a copy of their genome into the host cell genome is an essential step of the life cycle of retroviruses. The site of viral DNA integration, mediated by the viral-encoded integrase enzyme, has important consequences for both the virus and the host cell. The analysis of retroviral integration site distribution was facilitated by the availability of the human genome sequence, revealing the non-random feature of integration site selection and identifying different favored and disfavored genomic locations for individual retroviruses. This review will summarize the current knowledge about retroviral differences in their integration site preferences as well as the mechanisms involved in this process.
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Levin A, Rosenbluh J, Hayouka Z, Friedler A, Loyter A. Integration of HIV-1 DNA is regulated by interplay between viral rev and cellular LEDGF/p75 proteins. Mol Med 2009; 16:34-44. [PMID: 19855849 DOI: 10.2119/molmed.2009.00133] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 10/16/2009] [Indexed: 01/11/2023] Open
Abstract
The present work describes a novel interaction between the human immunodeficiency virus type 1 (HIV-1) Rev protein and the cellular lens epithelium-derived growth factor p75 (LEDGF/p75) protein in vitro and in virus-infected cells. Here we show, for the first time, that formation of an Rev-LEDGF/p75 complex is a crucial step in regulating viral cDNA integration. Coimmunoprecipitation experiments at various times after virus infection revealed that, first, an integrase enzyme (IN)-LEDGF/p75 complex is formed, which is then replaced by a Rev-LEDGF/p75 and Rev-IN complexes. This was supported by in vitro experiments showing that Rev promotes dissociation of the IN-LEDGF/p75 complex. Combination of the viral IN and the cellular LEDGF/p75 is required for proper integration of the viral cDNA into the host chromosomal DNA. Our findings demonstrate that integration of HIV-1 cDNA is regulated by an interplay between viral Rev and the host-cell LEDGF/p75 proteins.
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Affiliation(s)
- Aviad Levin
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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28
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Levin A, Hayouka Z, Brack-Werner R, Volsky DJ, Friedler A, Loyter A. Novel regulation of HIV-1 replication and pathogenicity: Rev inhibition of integration. Protein Eng Des Sel 2009; 22:753-63. [PMID: 19875511 DOI: 10.1093/protein/gzp060] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Following fusion of the human immunodeficiency virus type-1 (HIV-1) with host cells' membrane and reverse transcription of the viral RNA, the resulted cDNA is integrated into the host genome by the viral integrase enzyme (IN). Quantitative estimations have revealed that only 1-2 copies are integrated per infected cell, although many copies of the viral RNA are reverse-transcribed. The molecular mechanism that restricts the integration degree has not, so far, been elucidated. Following integration, expressed partially spliced and unspliced transcripts are exported from the nuclei by the viral Rev protein. Here, we show that in virally infected cells, the Rev interacts with the IN forming a Rev-IN complex and consequently limits the number of integration events. Disruption of the Rev-IN complex by selected IN-derived peptides or infection by a Rev-deficient virus stimulate integration resulting in large numbers of integration event/cell. Conversely, infection of Rev-expression cells blocks integration and inhibits virus production. Increased integration appears to correlate with increased cell death of infected cultures. Our results thus demonstrate a new regulatory function of Rev and probably establish a link between Rev restriction of HIV-1 integration and protection of HIV-1-infected cells from premature cell death.
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Affiliation(s)
- Aviad Levin
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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29
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Yu D, Wang W, Yoder A, Spear M, Wu Y. The HIV envelope but not VSV glycoprotein is capable of mediating HIV latent infection of resting CD4 T cells. PLoS Pathog 2009; 5:e1000633. [PMID: 19851458 PMCID: PMC2760144 DOI: 10.1371/journal.ppat.1000633] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Accepted: 09/25/2009] [Indexed: 01/14/2023] Open
Abstract
HIV fusion and entry into CD4 T cells are mediated by two receptors, CD4 and CXCR4. This receptor requirement can be abrogated by pseudotyping the virion with the vesicular stomatitis virus glycoprotein (VSV-G) that mediates viral entry through endocytosis. The VSV-G-pseudotyped HIV is highly infectious for transformed cells, although the virus circumvents the viral receptors and the actin cortex. In HIV infection, gp120 binding to the receptors also transduces signals. Recently, we demonstrated a unique requirement for CXCR4 signaling in HIV latent infection of blood resting CD4 T cells. Thus, we performed parallel studies in which the VSV-G-pseudotyped HIV was used to infect both transformed and resting T cells in the absence of coreceptor signaling. Our results indicate that in transformed T cells, the VSV-G-pseudotyping results in lower viral DNA synthesis but a higher rate of nuclear migration. However, in resting CD4 T cells, only the HIV envelope-mediated entry, but not the VSV-G-mediated endocytosis, can lead to viral DNA synthesis and nuclear migration. The viral particles entering through the endocytotic pathway were destroyed within 1–2 days. These results indicate that the VSV-G-mediated endocytotic pathway, although active in transformed cells, is defective and is not a pathway that can establish HIV latent infection of primary resting T cells. Our results highlight the importance of the genuine HIV envelope and its signaling capacity in the latent infection of blood resting T cells. These results also call for caution on the endocytotic entry model of HIV-1, and on data interpretation where the VSV-G-pseudotyped HIV was used for identifying HIV restriction factors in resting T cells. While receptor-mediated viral endocytosis or fusion with the cell membrane can be achieved through multiple surface molecules, the repetitious selection of two chemokine receptors, CCR5 or CXCR4, as the main HIV entry coreceptor implies an urgent viral need to exploit the chemotactic process in the immune system. Cytoskeletal rearrangement and cell migration are the primary consequences of chemotactic signaling. Nevertheless, previously published data demonstrated that depriving the virus of its signaling ability conferred higher infectivity through VSV-G-mediated endocytotic entry in transformed cells. We revisited the issue of chemokine coreceptor signaling and the role of cortical actin in HIV-1 latent infection of resting CD4 T cells, in which the virus can establish latency with a potential for productive replication upon T cell activation. Our results confirmed that only the genuine HIV-1 envelope protein, but not VSV-G, is capable of mediating latent infection of resting CD4 T cells. These findings highlight the importance of the HIV envelope and its signaling capacity in HIV infection of its natural target cells.
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Affiliation(s)
- Dongyang Yu
- Department of Molecular and Microbiology, George Mason University, Manassas, Virginia, United States of America
| | - Weifeng Wang
- Department of Molecular and Microbiology, George Mason University, Manassas, Virginia, United States of America
| | - Alyson Yoder
- Department of Molecular and Microbiology, George Mason University, Manassas, Virginia, United States of America
| | - Mark Spear
- Department of Molecular and Microbiology, George Mason University, Manassas, Virginia, United States of America
| | - Yuntao Wu
- Department of Molecular and Microbiology, George Mason University, Manassas, Virginia, United States of America
- * E-mail:
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