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Epigenetic Regulation of HIV-1 Sense and Antisense Transcription in Response to Latency-Reversing Agents. Noncoding RNA 2023; 9:ncrna9010005. [PMID: 36649034 PMCID: PMC9844351 DOI: 10.3390/ncrna9010005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/29/2022] [Accepted: 01/05/2023] [Indexed: 01/12/2023] Open
Abstract
Nucleosomes positioned on the HIV-1 5' long terminal repeat (LTR) regulate sense transcription as well as the establishment and maintenance of latency. A negative-sense promoter (NSP) in the 3' LTR expresses antisense transcripts with coding and non-coding activities. Previous studies identified cis-acting elements that modulate NSP activity. Here, we used the two chronically infected T cell lines, ACH-2 and J1.1, to investigate epigenetic regulation of NSP activity. We found that histones H3 and H4 are present on the 3' LTR in both cell lines. Following treatment with histone deacetylase inhibitors (HDACi), the levels of H3K27Ac increased and histone occupancy declined. HDACi treatment also led to increased levels of RNA polymerase II (RNPII) at NSP, and antisense transcription was induced with similar kinetics and to a similar extent as 5' LTR-driven sense transcription. We also detected H3K9me2 and H3K27me3 on NSP, along with the enzymes responsible for these epigenetic marks, namely G9a and EZH2, respectively. Treatment with their respective inhibitors had little or no effect on RNPII occupancy at the two LTRs, but it induced both sense and antisense transcription. Moreover, the increased expression of antisense transcripts in response to treatment with a panel of eleven latency-reversing agents closely paralleled and was often greater than the effect on sense transcripts. Thus, HIV-1 sense and antisense RNA expression are both regulated via acetylation and methylation of lysine 9 and 27 on histone H3. Since HIV-1 antisense transcripts act as non-coding RNAs promoting epigenetic silencing of the 5' LTR, our results suggest that the limited efficacy of latency-reversing agents in the context of 'shock and kill' cure strategies may be due to concurrent induction of antisense transcripts thwarting their effect on sense transcription.
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Sathiyamani B, Daniel EA, Ansar S, Esakialraj BH, Hassan S, Revanasiddappa PD, Keshavamurthy A, Roy S, Vetrivel U, Hanna LE. Structural analysis and molecular dynamics simulation studies of HIV-1 antisense protein predict its potential role in HIV replication and pathogenesis. Front Microbiol 2023; 14:1152206. [PMID: 37020719 PMCID: PMC10067880 DOI: 10.3389/fmicb.2023.1152206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 03/01/2023] [Indexed: 04/07/2023] Open
Abstract
The functional significance of the HIV-1 Antisense Protein (ASP) has been a paradox since its discovery. The expression of this protein in HIV-1-infected cells and its involvement in autophagy, transcriptional regulation, and viral latency have sporadically been reported in various studies. Yet, the definite role of this protein in HIV-1 infection remains unclear. Deciphering the 3D structure of HIV-1 ASP would throw light on its potential role in HIV lifecycle and host-virus interaction. Hence, using extensive molecular modeling and dynamics simulation for 200 ns, we predicted the plausible 3D-structures of ASP from two reference strains of HIV-1 namely, Indie-C1 (subtype-C) and NL4-3 (subtype-B) so as to derive its functional implication through structural domain analysis. In spite of sequence and structural differences in subtype B and C ASP, both structures appear to share common domains like the Von Willebrand Factor Domain-A (VWFA), Integrin subunit alpha-X (ITGSX), and ETV6-Transcriptional repressor, thereby reiterating the potential role of HIV-1 ASP in transcriptional repression and autophagy, as reported in earlier studies. Gromos-based cluster analysis of the centroid structures also reassured the accuracy of the prediction. This is the first study to elucidate a highly plausible structure for HIV-1 ASP which could serve as a feeder for further experimental validation studies.
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Affiliation(s)
- Balakumaran Sathiyamani
- Department of Virology and Biotechnology, National Institute for Research in Tuberculosis, Chennai, Tamil Nadu, India
- University of Madras, Chennai, India
| | - Evangeline Ann Daniel
- Department of Virology and Biotechnology, National Institute for Research in Tuberculosis, Chennai, Tamil Nadu, India
- University of Madras, Chennai, India
| | - Samdani Ansar
- Center for Bioinformatics, Vision Research Foundation, Sankara Nethralaya, Chennai, Tamil Nadu, India
| | - Bennett Henzeler Esakialraj
- Department of Virology and Biotechnology, National Institute for Research in Tuberculosis, Chennai, Tamil Nadu, India
| | - Sameer Hassan
- Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden
| | | | - Amrutha Keshavamurthy
- Department of Biotechnology, Siddaganga Institute of Technology, Tumakuru, Karnataka, India
| | - Sujata Roy
- Department of Biotechnology, Rajalakshmi Engineering College, Chennai, Tamil Nadu, India
| | - Umashankar Vetrivel
- Department of Virology and Biotechnology, National Institute for Research in Tuberculosis, Chennai, Tamil Nadu, India
- *Correspondence: Luke Elizabeth Hanna, ; Umashankar Vetrivel,
| | - Luke Elizabeth Hanna
- Department of Virology and Biotechnology, National Institute for Research in Tuberculosis, Chennai, Tamil Nadu, India
- *Correspondence: Luke Elizabeth Hanna, ; Umashankar Vetrivel,
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Toyoda K, Matsuoka M. Functional and Pathogenic Roles of Retroviral Antisense Transcripts. Front Immunol 2022; 13:875211. [PMID: 35572593 PMCID: PMC9100821 DOI: 10.3389/fimmu.2022.875211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Accepted: 04/06/2022] [Indexed: 11/13/2022] Open
Abstract
Exogenous retroviruses such as human immunodeficiency virus type 1 (HIV-1), human T-cell leukemia virus type 1 (HTLV-1) and bovine leukemia virus (BLV) can cause various diseases including immunodeficiency, inflammatory diseases and hematologic malignancies. These retroviruses persistently infect their hosts. Therefore, they need to evade host immune surveillance. One way in which these viruses might avoid immune detection is to utilize functional RNAs, rather than proteins, for certain activities, because RNAs are not recognized by the host immune system. HTLV-1 encodes the HTLV-1 bZIP factor (HBZ) gene in the antisense strand of the provirus. The HBZ protein is constantly expressed in HTLV-1 carriers and patients with adult T-cell leukemia-lymphoma, and it plays critical roles in pathogenesis. However, HBZ not only encodes this protein, but also functions as mRNA. Thus, HBZ gene mRNA is bifunctional. HIV-1 and BLV also encode long non-coding RNAs as antisense transcripts. In this review, we reshape our current understanding of how these antisense transcripts function and how they influence disease pathogenesis.
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Retroviral Antisense Transcripts and Genes: 33 Years after First Predicted, a Silent Retroviral Revolution? Viruses 2021; 13:v13112221. [PMID: 34835027 PMCID: PMC8622228 DOI: 10.3390/v13112221] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 10/28/2021] [Accepted: 11/02/2021] [Indexed: 12/29/2022] Open
Abstract
Paradigm shifts throughout the history of microbiology have typically been ignored, or met with skepticism and resistance, by the scientific community. This has been especially true in the field of virology, where the discovery of a “contagium vivum fluidum”, or infectious fluid remaining after excluding bacteria by filtration, was initially ignored because it did not coincide with the established view of microorganisms. Subsequent studies on such infectious agents, eventually termed “viruses”, were met with skepticism. However, after an abundance of proof accumulated, viruses were eventually acknowledged as defined microbiological entities. Next, the proposed role of viruses in oncogenesis in animals was disputed, as was the unique mechanism of genome replication by reverse transcription of RNA by the retroviruses. This same pattern of skepticism holds true for the prediction of the existence of retroviral “antisense” transcripts and genes. From the time of their discovery, it was thought that retroviruses encoded proteins on only one strand of proviral DNA. However, in 1988, it was predicted that human immunodeficiency virus type 1 (HIV-1), and other retroviruses, express an antisense protein encoded on the DNA strand opposite that encoding the known viral proteins. Confirmation came quickly with the characterization of the antisense protein, HBZ, of the human T-cell leukemia virus type 1 (HTLV-1), and the finding that both the protein and its antisense mRNA transcript play key roles in viral replication and pathogenesis. However, acceptance of the existence, and potential importance, of a corresponding antisense transcript and protein (ASP) in HIV-1 infection and pathogenesis has lagged, despite gradually accumulating theoretical and experimental evidence. The most striking theoretical evidence is the finding that asp is highly conserved in group M viruses and correlates exclusively with subtypes, or clades, responsible for the AIDS pandemic. This review outlines the history of the major shifts in thought pertaining to the nature and characteristics of viruses, and in particular retroviruses, and details the development of the hypothesis that retroviral antisense transcripts and genes exist. We conclude that there is a need to accelerate studies on ASP, and its transcript(s), with the view that both may be important, and overlooked, targets in anti-HIV therapeutic and vaccine strategies.
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Gholizadeh Z, Iqbal MS, Li R, Romerio F. The HIV-1 Antisense Gene ASP: The New Kid on the Block. Vaccines (Basel) 2021; 9:vaccines9050513. [PMID: 34067514 PMCID: PMC8156140 DOI: 10.3390/vaccines9050513] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/04/2021] [Accepted: 05/13/2021] [Indexed: 01/14/2023] Open
Abstract
Viruses have developed incredibly creative ways of making a virtue out of necessity, including taking full advantage of their small genomes. Indeed, viruses often encode multiple proteins within the same genomic region by using two or more reading frames in both orientations through a process called overprinting. Complex retroviruses provide compelling examples of that. The human immunodeficiency virus type 1 (HIV-1) genome expresses sixteen proteins from nine genes that are encoded in the three positive-sense reading frames. In addition, the genome of some HIV-1 strains contains a tenth gene in one of the negative-sense reading frames. The so-called Antisense Protein (ASP) gene overlaps the HIV-1 Rev Response Element (RRE) and the envelope glycoprotein gene, and encodes a highly hydrophobic protein of ~190 amino acids. Despite being identified over thirty years ago, relatively few studies have investigated the role that ASP may play in the virus lifecycle, and its expression in vivo is still questioned. Here we review the current knowledge about ASP, and we discuss some of the many unanswered questions.
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Li R, Sklutuis R, Groebner JL, Romerio F. HIV-1 Natural Antisense Transcription and Its Role in Viral Persistence. Viruses 2021; 13:v13050795. [PMID: 33946840 PMCID: PMC8145503 DOI: 10.3390/v13050795] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 12/11/2022] Open
Abstract
Natural antisense transcripts (NATs) represent a class of RNA molecules that are transcribed from the opposite strand of a protein-coding gene, and that have the ability to regulate the expression of their cognate protein-coding gene via multiple mechanisms. NATs have been described in many prokaryotic and eukaryotic systems, as well as in the viruses that infect them. The human immunodeficiency virus (HIV-1) is no exception, and produces one or more NAT from a promoter within the 3’ long terminal repeat. HIV-1 antisense transcripts have been the focus of several studies spanning over 30 years. However, a complete appreciation of the role that these transcripts play in the virus lifecycle is still lacking. In this review, we cover the current knowledge about HIV-1 NATs, discuss some of the questions that are still open and identify possible areas of future research.
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Affiliation(s)
- Rui Li
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA;
| | - Rachel Sklutuis
- HIV Dynamics and Replication Program, Host-Virus Interaction Branch, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA; (R.S.); (J.L.G.)
| | - Jennifer L. Groebner
- HIV Dynamics and Replication Program, Host-Virus Interaction Branch, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA; (R.S.); (J.L.G.)
| | - Fabio Romerio
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA;
- Correspondence:
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Savoret J, Mesnard JM, Gross A, Chazal N. Antisense Transcripts and Antisense Protein: A New Perspective on Human Immunodeficiency Virus Type 1. Front Microbiol 2021; 11:625941. [PMID: 33510738 PMCID: PMC7835632 DOI: 10.3389/fmicb.2020.625941] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 12/14/2020] [Indexed: 12/13/2022] Open
Abstract
It was first predicted in 1988 that there may be an Open Reading Frame (ORF) on the negative strand of the Human Immunodeficiency Virus type 1 (HIV-1) genome that could encode a protein named AntiSense Protein (ASP). In spite of some controversy, reports began to emerge some years later describing the detection of HIV-1 antisense transcripts, the presence of ASP in transfected and infected cells, and the existence of an immune response targeting ASP. Recently, it was established that the asp gene is exclusively conserved within the pandemic group M of HIV-1. In this review, we summarize the latest findings on HIV-1 antisense transcripts and ASP, and we discuss their potential functions in HIV-1 infection together with the role played by antisense transcripts and ASPs in some other viruses. Finally, we suggest pathways raised by the study of antisense transcripts and ASPs that may warrant exploration in the future.
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Affiliation(s)
- Juliette Savoret
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, Université de Montpellier, Montpellier, France
| | - Jean-Michel Mesnard
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, Université de Montpellier, Montpellier, France
| | - Antoine Gross
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, Université de Montpellier, Montpellier, France
| | - Nathalie Chazal
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, Université de Montpellier, Montpellier, France
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Savoret J, Chazal N, Moles JP, Tuaillon E, Boufassa F, Meyer L, Lecuroux C, Lambotte O, Van De Perre P, Mesnard JM, Gross A. A Pilot Study of the Humoral Response Against the AntiSense Protein (ASP) in HIV-1-Infected Patients. Front Microbiol 2020; 11:20. [PMID: 32117090 PMCID: PMC7025555 DOI: 10.3389/fmicb.2020.00020] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 01/07/2020] [Indexed: 12/12/2022] Open
Abstract
The existence of an antisense Open Reading Frame (ORF) that encodes a putative AntiSense Protein (ASP) on the proviral genome of Human Immunodeficiency Virus type 1 (HIV-1) was a source of debate for 30 years. During the last years, some progresses have been made to characterize the cellular immune response against ASP in HIV-1 seropositive patients. However, no tools were available for the detection of antibodies to ASP in the plasma of HIV-1-infected patients during the natural course of the infection. The aim of our study was to develop a Luciferase Immuno-Precipitation System (LIPS) to monitor the quantitative detection of ASP-specific antibodies in the plasma of HIV-1-infected patients [antiretroviral therapy (ART) naive-patients, patients under ART and HIV-1 controllers], patients who discontinued antiretroviral drugs (ARV). We further used this approach to delineate the epitopes of ASP targeted by antibodies. Antibodies directed against ASP were detected in 3 out of 19 patients who discontinued ARV (15%) and in 1 out of 10 ART-naive patients (10%), but were neither detected in HIV-1 infected patients under ART nor in HIV-1 controllers. Individual variations in levels of ASP-specific antibodies were detected overtime. Both the conserved prolin-rich motif and the core 60–189 region of ASP were found to be essential for antibody recognition in the four patients tested positive for anti-ASP antibodies, who were all untreated at the time of sampling. Moreover, for two of these patients, increased levels of ASP-specific antibodies were observed concomitantly to viremia declines. Overall, our method may represent a useful tool to detect a humoral response to ASP in HIV-1-infected patients, which allowed us to confirm the expression of ASP during the course of HIV-1 infection. Further studies will be needed to fully characterize the humoral response to ASP in HIV-1-infected patients.
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Affiliation(s)
| | | | - Jean-Pierre Moles
- Pathogenesis and Control of Chronic Infections, INSERM, Etablissement Français du Sang, University of Montpellier, Montpellier, France
| | - Edouard Tuaillon
- Pathogenesis and Control of Chronic Infections, INSERM, Etablissement Français du Sang, University of Montpellier, CHU Montpellier, Montpellier, France
| | - Faroudy Boufassa
- INSERM CESP U1018, Université Paris-Sud, Le Kremlin-Bicêtre, France
| | - Laurence Meyer
- INSERM CESP U1018, Université Paris-Sud, Le Kremlin-Bicêtre, France
| | | | - Olivier Lambotte
- Department of Internal Medicine and Clinical Immunology, Bicêtre University Hospital, Le Kremlin-Bicêtre, France.,INSERM, CEA UMR 1184, Université Paris-Sud, Le Kremlin-Bicêtre, France
| | - Philippe Van De Perre
- Pathogenesis and Control of Chronic Infections, INSERM, Etablissement Français du Sang, University of Montpellier, CHU Montpellier, Montpellier, France
| | | | - Antoine Gross
- IRIM, Université de Montpellier, CNRS, Montpellier, France
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Affram Y, Zapata JC, Gholizadeh Z, Tolbert WD, Zhou W, Iglesias-Ussel MD, Pazgier M, Ray K, Latinovic OS, Romerio F. The HIV-1 Antisense Protein ASP Is a Transmembrane Protein of the Cell Surface and an Integral Protein of the Viral Envelope. J Virol 2019; 93:e00574-19. [PMID: 31434734 PMCID: PMC6803264 DOI: 10.1128/jvi.00574-19] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 08/14/2019] [Indexed: 12/13/2022] Open
Abstract
The negative strand of HIV-1 encodes a highly hydrophobic antisense protein (ASP) with no known homologs. The presence of humoral and cellular immune responses to ASP in HIV-1 patients indicates that ASP is expressed in vivo, but its role in HIV-1 replication remains unknown. We investigated ASP expression in multiple chronically infected myeloid and lymphoid cell lines using an anti-ASP monoclonal antibody (324.6) in combination with flow cytometry and microscopy approaches. At baseline and in the absence of stimuli, ASP shows polarized subnuclear distribution, preferentially in areas with low content of suppressive epigenetic marks. However, following treatment with phorbol 12-myristate 13-acetate (PMA), ASP translocates to the cytoplasm and is detectable on the cell surface, even in the absence of membrane permeabilization, indicating that 324.6 recognizes an ASP epitope that is exposed extracellularly. Further, surface staining with 324.6 and anti-gp120 antibodies showed that ASP and gp120 colocalize, suggesting that ASP might become incorporated in the membranes of budding virions. Indeed, fluorescence correlation spectroscopy studies showed binding of 324.6 to cell-free HIV-1 particles. Moreover, 324.6 was able to capture and retain HIV-1 virions with efficiency similar to that of the anti-gp120 antibody VRC01. Our studies indicate that ASP is an integral protein of the plasma membranes of chronically infected cells stimulated with PMA, and upon viral budding, ASP becomes a structural protein of the HIV-1 envelope. These results may provide leads to investigate the possible role of ASP in the virus replication cycle and suggest that ASP may represent a new therapeutic or vaccine target.IMPORTANCE The HIV-1 genome contains a gene expressed in the opposite, or antisense, direction to all other genes. The protein product of this antisense gene, called ASP, is poorly characterized, and its role in viral replication remains unknown. We provide evidence that the antisense protein, ASP, of HIV-1 is found within the cell nucleus in unstimulated cells. In addition, we show that after PMA treatment, ASP exits the nucleus and localizes on the cell membrane. Moreover, we demonstrate that ASP is present on the surfaces of viral particles. Altogether, our studies identify ASP as a new structural component of HIV-1 and show that ASP is an accessory protein that promotes viral replication. The presence of ASP on the surfaces of both infected cells and viral particles might be exploited therapeutically.
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Affiliation(s)
- Yvonne Affram
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Juan C Zapata
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Zahra Gholizadeh
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - William D Tolbert
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Wei Zhou
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Maria D Iglesias-Ussel
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Marzena Pazgier
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Krishanu Ray
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Olga S Latinovic
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Fabio Romerio
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, Maryland, USA
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Mancarella A, Procopio FA, Achsel T, De Crignis E, Foley BT, Corradin G, Bagni C, Pantaleo G, Graziosi C. Detection of antisense protein (ASP) RNA transcripts in individuals infected with human immunodeficiency virus type 1 (HIV-1). J Gen Virol 2019; 100:863-876. [PMID: 30896385 DOI: 10.1099/jgv.0.001244] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The detection of antisense RNA is hampered by reverse transcription (RT) non-specific priming, due to the ability of RNA secondary structures to prime RT in the absence of specific primers. The detection of antisense RNA by conventional RT-PCR does not allow assessment of the polarity of the initial RNA template, causing the amplification of non-specific cDNAs. In this study we have developed a modified protocol for the detection of human immunodeficiency virus type 1 (HIV-1) antisense protein (ASP) RNA. Using this approach, we have identified ASP transcripts in CD4+ T cells isolated from five HIV-infected individuals, either untreated or under suppressive therapy. We show that ASP RNA can be detected in stimulated CD4+ T cells from both groups of patients, but not in unstimulated cells. We also show that in untreated patients, the patterns of expression of ASP and env are very similar, with the levels of ASP RNA being markedly lower than those of env. Treatment of cells from one viraemic patient with α-amanitin greatly reduces the rate of ASP RNA synthesis, suggesting that it is associated with RNA polymerase II, the central enzyme in the transcription of protein-coding genes. Our data represent the first nucleotide sequences obtained in patients for ASP, demonstrating that its transcription indeed occurs in those HIV-1 lineages in which the ASP open reading frame is present.
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Affiliation(s)
- Antonio Mancarella
- 1Division of Immunology and Allergy, Lausanne University Hospital, Switzerland
| | | | - Tilmann Achsel
- 2Department of Fundamental Neuroscience, University of Lausanne, Switzerland
| | - Elisa De Crignis
- 3Department of Biochemistry, Erasmus Medical Center, Rotterdam, The Netherlands.,†Present address: Clinical Trial Office, CRO Aviano National Cancer Institute, Aviano, Italy
| | - Brian T Foley
- 4Theoretical Biology and Biophysics Group, Los Alamos National Laboratories, Los Alamos, New Mexico, USA
| | | | - Claudia Bagni
- 2Department of Fundamental Neuroscience, University of Lausanne, Switzerland
| | - Giuseppe Pantaleo
- 1Division of Immunology and Allergy, Lausanne University Hospital, Switzerland
| | - Cecilia Graziosi
- 1Division of Immunology and Allergy, Lausanne University Hospital, Switzerland
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HIV-1 Antisense Protein of Different Clades Induces Autophagy and Associates with the Autophagy Factor p62. J Virol 2019; 93:JVI.01757-18. [PMID: 30404795 DOI: 10.1128/jvi.01757-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Accepted: 10/26/2018] [Indexed: 12/22/2022] Open
Abstract
The existence of the antisense transcript-encoded HIV-1 antisense protein (ASP) was recently reinforced by in silico analyses providing evidence for recent appearance of this gene in the viral genome. Our previous studies led to the detection of ASP in various cell lines by Western blotting, flow cytometry, and confocal microscopy analyses and reported that it induced autophagy, potentially through multimer formation. Here, our goals were to assess autophagy induction by ASP from different clades and to identify the implicated autophagy factors. We first demonstrated that ASP formed multimers, partly through its amino-terminal region and cysteine residues. Removal of this region was further associated with lower induction of autophagy, as assessed by autophagosome formation. ASPs from different clades (A, B, C, D, and G) were tested next and were detected in monomeric and multimeric forms at various levels, and all induced autophagy (clade A ASP was less efficient), as determined by LC3-II and p62 (SQSTM1) levels. Furthermore, CRISPR-based knockout of ATG5, ATG7, and p62 genes led to increased ASP levels. Confocal microscopy analyses showed that ASP colocalized with p62 and LC3-II in autophagosome-like structures. Coimmunoprecipitation experiments further demonstrated that p62 associated with ASP through its PB1 domain. Interestingly, immunoprecipitation experiments supported the idea that ASP is ubiquitinated and that ubiquitination was modulating its stability. We are thus suggesting that ASP induces autophagy through p62 interaction and that its abundance is controlled by autophagy, in which ubiquitin plays an important role. Understanding the mechanisms underlying ASP degradation is essential to better assess its function.IMPORTANCE In the present study, we provide the first evidence that a new HIV-1 protein termed ASP derived from different clades acts similarly in inducing autophagy, an important cellular process implicated in the degradation of excess or defective cellular material. We have gained further knowledge on the mechanism mediating the activation of autophagy. Our studies have important ramifications in the understanding of viral replication and the pathogenesis associated with HIV-1 in infected individuals. Indeed, autophagy is implicated in antigen presentation during immune response and could thus be rendered inefficient in infected cells, such as dendritic cells. Furthermore, a possible link with HIV-1-associated neurological disorder (HAND) might also be a possible association with the capacity of ASP to induce autophagy. Our studies hence demonstrate the importance in conducting further studies on this protein as it could represent a new interesting target for antiretroviral therapies and vaccine design.
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Peng BJ, Carlson JM, Liu MKP, Gao F, Goonetilleke N, McMichael AJ, Borrow P, Gilmour J, Heath SL, Hunter E, Bansal A, Goepfert PA. Antisense-Derived HIV-1 Cryptic Epitopes Are Not Major Drivers of Viral Evolution during the Acute Phase of Infection. J Virol 2018; 92:e00711-18. [PMID: 30021907 PMCID: PMC6146806 DOI: 10.1128/jvi.00711-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 07/07/2018] [Indexed: 01/31/2023] Open
Abstract
While prior studies have demonstrated that CD8 T cell responses to cryptic epitopes (CE) are readily detectable during HIV-1 infection, their ability to drive escape mutations following acute infection is unknown. We predicted 66 CE in a Zambian acute infection cohort based on escape mutations occurring within or near the putatively predicted HLA-I-restricted epitopes. The CE were evaluated for CD8 T cell responses for patients with chronic and acute HIV infections. Of the 66 predicted CE, 10 were recognized in 8/32 and 4/11 patients with chronic and acute infections, respectively. The immunogenic CE were all derived from a single antisense reading frame within pol However, when these CE were tested using longitudinal study samples, CE-specific T cell responses were detected but did not consistently select for viral escape mutations. Thus, while we demonstrated that CE are immunogenic in acute infection, the immune responses to CE are not major drivers of viral escape in the initial stages of HIV infection. The latter finding may be due to either the subdominant nature of CE-specific responses, the low antigen sensitivity, or the magnitude of CE responses during acute infections.IMPORTANCE Although prior studies demonstrated that cryptic epitopes of HIV-1 induce CD8 T cell responses, evidence that targeting these epitopes drives HIV escape mutations has been substantially limited, and no studies have addressed this question following acute infection. In this comprehensive study, we utilized longitudinal viral sequencing data obtained from three separate acute infection cohorts to predict potential cryptic epitopes based on HLA-I-associated viral escape. Our data show that cryptic epitopes are immunogenic during acute infection and that many of the responses they elicit are toward translation products of HIV-1 antisense reading frames. However, despite cryptic epitope targeting, our study did not find any evidence of early CD8-mediated immune escape. Nevertheless, improving cryptic epitope-specific CD8 T cell responses may still be beneficial in both preventative and therapeutic HIV-1 vaccines.
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Affiliation(s)
- Binghao J Peng
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | | | - Michael K P Liu
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Feng Gao
- Department of Medicine, Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina, USA
| | - Nilu Goonetilleke
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Andrew J McMichael
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Persephone Borrow
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Jill Gilmour
- IAVI Human Immunology Laboratory, Imperial College London, London, United Kingdom
| | - Sonya L Heath
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Eric Hunter
- Emory Vaccine Center at Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, USA
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia, USA
| | - Anju Bansal
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Paul A Goepfert
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Applications of the FIV Model to Study HIV Pathogenesis. Viruses 2018; 10:v10040206. [PMID: 29677122 PMCID: PMC5923500 DOI: 10.3390/v10040206] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 04/17/2018] [Accepted: 04/17/2018] [Indexed: 12/15/2022] Open
Abstract
Feline immunodeficiency virus (FIV) is a naturally-occurring retrovirus that infects domestic and non-domestic feline species, producing progressive immune depletion that results in an acquired immunodeficiency syndrome (AIDS). Much has been learned about FIV since it was first described in 1987, particularly in regard to its application as a model to study the closely related lentivirus, human immunodeficiency virus (HIV). In particular, FIV and HIV share remarkable structure and sequence organization, utilize parallel modes of receptor-mediated entry, and result in a similar spectrum of immunodeficiency-related diseases due to analogous modes of immune dysfunction. This review summarizes current knowledge of FIV infection kinetics and the mechanisms of immune dysfunction in relation to opportunistic disease, specifically in regard to studying HIV pathogenesis. Furthermore, we present data that highlight changes in the oral microbiota and oral immune system during FIV infection, and outline the potential for the feline model of oral AIDS manifestations to elucidate pathogenic mechanisms of HIV-induced oral disease. Finally, we discuss advances in molecular biology, vaccine development, neurologic dysfunction, and the ability to apply pharmacologic interventions and sophisticated imaging technologies to study experimental and naturally occurring FIV, which provide an excellent, but often overlooked, resource for advancing therapies and the management of HIV/AIDS.
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Implication of Different HIV-1 Genes in the Modulation of Autophagy. Viruses 2017; 9:v9120389. [PMID: 29258265 PMCID: PMC5744163 DOI: 10.3390/v9120389] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 12/12/2017] [Accepted: 12/13/2017] [Indexed: 12/24/2022] Open
Abstract
Autophagy is a complex cellular degradation pathway, which plays important roles in the regulation of several developmental processes, cellular stress responses, and immune responses induced by pathogens. A number of studies have previously demonstrated that HIV-1 was capable of altering the regulation of autophagy and that this biological process could be induced in uninfected and infected cells. Furthermore, previous reports have indicated that the involvement of HIV-1 in autophagy regulation is a complex phenomenon and that different viral proteins are contributing in its modulation upon viral infection. Herein, we review the recent literature over the complex crosstalk of the autophagy pathway and HIV-1, with a particular focus on HIV-1 viral proteins, which have been shown to modulate autophagy.
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Zapata JC, Campilongo F, Barclay RA, DeMarino C, Iglesias-Ussel MD, Kashanchi F, Romerio F. The Human Immunodeficiency Virus 1 ASP RNA promotes viral latency by recruiting the Polycomb Repressor Complex 2 and promoting nucleosome assembly. Virology 2017; 506:34-44. [PMID: 28340355 PMCID: PMC5505171 DOI: 10.1016/j.virol.2017.03.002] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/03/2017] [Accepted: 03/05/2017] [Indexed: 01/04/2023]
Abstract
Various epigenetic marks at the HIV-1 5′LTR suppress proviral expression and promote latency. Cellular antisense transcripts known as long noncoding RNAs (lncRNAs) recruit the polycomb repressor complex 2 (PRC2) to gene promoters, which catalyzes trimethylation of lysine 27 on histone H3 (H3K27me3), thus promoting nucleosome assembly and suppressing gene expression. We found that an HIV-1 antisense transcript expressed from the 3′LTR and encoding the antisense protein ASP promotes proviral latency. Expression of ASP RNA reduced HIV-1 replication in Jurkat cells. Moreover, ASP RNA expression promoted the establishment and maintenance of HIV-1 latency in Jurkat E4 cells. We show that this transcript interacts with and recruits PRC2 to the HIV-1 5′LTR, increasing accumulation of the suppressive epigenetic mark H3K27me3, while reducing RNA Polymerase II and thus proviral transcription. Altogether, our results suggest that the HIV-1 ASP transcript promotes epigenetic silencing of the HIV-1 5′LTR and proviral latency through the PRC2 pathway.
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Affiliation(s)
- Juan C Zapata
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Federica Campilongo
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Robert A Barclay
- Laboratory of Molecular Virology, George Mason University, Manassas, VA, USA
| | - Catherine DeMarino
- Laboratory of Molecular Virology, George Mason University, Manassas, VA, USA
| | - Maria D Iglesias-Ussel
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Fatah Kashanchi
- Laboratory of Molecular Virology, George Mason University, Manassas, VA, USA
| | - Fabio Romerio
- Institute of Human Virology, University of Maryland School of Medicine, Baltimore, MD, USA.
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16
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Manghera M, Magnusson A, Douville RN. The sense behind retroviral anti-sense transcription. Virol J 2017; 14:9. [PMID: 28088235 PMCID: PMC5237517 DOI: 10.1186/s12985-016-0667-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 12/09/2016] [Indexed: 12/15/2022] Open
Abstract
Retroviruses are known to rely extensively on the expression of viral proteins from the sense proviral genomic strand. Yet, the production of regulatory retroviral proteins from antisense-encoded viral genes is gaining research attention, due to their clinical significance. This report will discuss what is known about antisense transcription in Retroviridae, and provide new information about antisense transcriptional regulation through a comparison of Human Immunodeficiency Virus (HIV), Human T-cell Lymphotrophic Virus (HTLV-1) and endogenous retrovirus-K (ERVK) long terminal repeats (LTRs). We will attempt to demonstrate that the potential for antisense transcription is more widespread within retroviruses than has been previously appreciated, with this feature being the rule, rather than the exception.
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Affiliation(s)
- Mamneet Manghera
- Department of Immunology, University of Manitoba, Winnipeg, MB, Canada
| | - Alycia Magnusson
- Department of Biology, The University of Winnipeg, Winnipeg, MB, Canada
| | - Renée N Douville
- Department of Immunology, University of Manitoba, Winnipeg, MB, Canada. .,Department of Biology, The University of Winnipeg, Winnipeg, MB, Canada.
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Concomitant emergence of the antisense protein gene of HIV-1 and of the pandemic. Proc Natl Acad Sci U S A 2016; 113:11537-11542. [PMID: 27681623 DOI: 10.1073/pnas.1605739113] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Recent experiments provide sound arguments in favor of the in vivo expression of the AntiSense Protein (ASP) of HIV-1. This putative protein is encoded on the antisense strand of the provirus genome and entirely overlapped by the env gene with reading frame -2. The existence of ASP was suggested in 1988, but is still controversial, and its function has yet to be determined. We used a large dataset of ∼23,000 HIV-1 and SIV sequences to study the origin, evolution, and conservation of the asp gene. We found that the ASP ORF is specific to group M of HIV-1, which is responsible for the human pandemic. Moreover, the correlation between the presence of asp and the prevalence of HIV-1 groups and M subtypes appeared to be statistically significant. We then looked for evidence of selection pressure acting on asp Using computer simulations, we showed that the conservation of the ASP ORF in the group M could not be due to chance. Standard methods were ineffective in disentangling the two selection pressures imposed by both the Env and ASP proteins-an expected outcome with overlaps in frame -2. We thus developed a method based on careful evolutionary analysis of the presence/absence of stop codons, revealing that ASP does impose significant selection pressure. All of these results support the idea that asp is the 10th gene of HIV-1 group M and indicate a correlation with the spread of the pandemic.
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Dimonte S. Different HIV-1 env frames: gp120 and ASP (antisense protein) biosynthesis, and theirs co-variation tropic amino acid signatures in X4- and R5-viruses. J Med Virol 2016; 89:112-122. [PMID: 27328810 DOI: 10.1002/jmv.24611] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/20/2016] [Indexed: 11/07/2022]
Abstract
Antisense protein (ASP) is the new actor of viral life of Human Immunodeficiency Virus type 1 (HIV-1) although proposed above 20 years ago. The asp ORF is into complementary strand of the gp120/gp41 junction of env gene. The ASP biological role remains little known. Knowing the Env markers of viral tropism, a dataset of sequences (660 strains) was used to analyze the hypothetical ASP involvement in CCR5 (R5) and/or CXCR4 (X4) co-receptor interaction. Preliminarily, prevalence of ASP and gp120V3 mutations was performed; following association among mutations were elaborate. The classical V3 tropic-signatures were confirmed, and 36 R5- and 22 X4-tropic ASP mutations were found. Moreover, by analyzing the ASP sequences, 36 out of 179 amino acid positions significantly associated with different co-receptor usage were found. Several statistically significant associations between gp120V3 and ASP mutations were observed. The dendrogram showed the existence of a cluster associated with R5-usage and a large cluster associated with X4-usage. These results show that gp120V3 and specific amino acid changes in ASP are associated together with CXCR4 and/or CCR5-usage. These findings implement previous observations on unclear ASP functions. J. Med. Virol. 89:112-122, 2017. © 2016 Wiley Periodicals, Inc.
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Bansal A, Mann T, Sterrett S, Peng BJ, Bet A, Carlson JM, Goepfert PA. Enhanced Recognition of HIV-1 Cryptic Epitopes Restricted by HLA Class I Alleles Associated With a Favorable Clinical Outcome. J Acquir Immune Defic Syndr 2015; 70:1-8. [PMID: 26322665 DOI: 10.1097/qai.0000000000000700] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Cryptic epitopes (CEs) are peptides derived from the translation of 1 or more of the 5 alternative reading frames (ARFs; 2 sense and 3 antisense) of genes. Here, we compared response rates to HIV-1-specific CE predicted to be restricted by HLA-I alleles associated with protection against disease progression to those without any such association. METHODS Peptides (9mer to 11mer) were designed based on HLA-I-binding algorithms for B*27, B*57, or B*5801 (protective alleles) and HLA-B*5301 or B*5501 (nonprotective allele) in all 5 ARFs of the 9 HIV-1 encoded proteins. Peptides with >50% probability of being an epitope (n = 231) were tested for T-cell responses in an IFN-γ enzyme-linked immunosorbent spot (ELISpot) assay. Peripheral blood mononuclear cell samples from HIV-1 seronegative donors (n = 42) and HIV-1 seropositive patients with chronic clade B infections (n = 129) were used. RESULTS Overall, 16%, 2%, and 2% of chronic HIV infected patients had CE responses by IFN-γ ELISpot in the protective, nonprotective, and seronegative groups, respectively (P = 0.009, Fischer exact test). Twenty novel CE-specific responses were mapped (median magnitude of 95 spot forming cells/10 peripheral blood mononuclear cells), and most were both antisense derived (90%) and represented ARFs of accessory proteins (55%). CE-specific CD8 T cells were multifunctional and proliferated when assessed by intracellular cytokine staining. CONCLUSIONS CE responses were preferentially restricted by the protective HLA-I alleles in HIV-1 infection, suggesting that they may contribute to viral control in this group of patients.
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Affiliation(s)
- Anju Bansal
- *Department of Medicine, University of Alabama at Birmingham, Birmingham, AL; and †Microsoft Research, Redmond, WA
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HIV-1 RNAs: sense and antisense, large mRNAs and small siRNAs and miRNAs. Curr Opin HIV AIDS 2015; 10:103-9. [PMID: 25565176 DOI: 10.1097/coh.0000000000000135] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW This review summarizes recent findings concerning the ever-growing HIV-1 RNA population. RECENT FINDINGS The retrovirus HIV-1 has an RNA genome that is converted into DNA and is integrated into the genome of the infected host cell. Transcription from the long terminal repeat-encoded promoter results in the production of a full-length genomic RNA and multiple spliced mRNAs. Recent experiments, mainly based on next-generation sequencing, provided evidence for several additional HIV-encoded RNAs, including antisense RNAs and virus-encoded microRNAs. SUMMARY We will survey recent findings related to HIV-1 RNA biosynthesis, especially regulatory mechanisms that control initiation of transcription, capping and polyadenylation. We zoom in on the diversity of HIV-1 derived RNA transcripts, their mode of synthesis and proposed functions in the infected cell. Special attention is paid to the viral transacting responsive RNA hairpin motif that has been suggested to encode microRNAs.
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21
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Does chronic infection in retroviruses have a sense? Trends Microbiol 2015; 23:367-75. [PMID: 25701112 DOI: 10.1016/j.tim.2015.01.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Revised: 01/06/2015] [Accepted: 01/20/2015] [Indexed: 01/12/2023]
Abstract
Over recent years, retroviral gene expression has been shown to depend on a promoter that is bidirectional. This promoter activity is likely to occur at either end of the retroviral genome and has important consequences at the level of retroviral gene expression. This review focuses on the recent discovery of retroviral antisense genes termed HBZ [in human T-cell leukemia virus type 1 (HTLV-1)] and ASP (in HIV-1) in terms of their function and the regulation of their expression, both of which are interconnected with the expression and function of other viral proteins. Emphasis is also given to the potential implication of these proteins in the maintenance of chronic infection in infected individuals. In light of recent findings, the discovery of these new genes opens a new avenue for the future treatment of HTLV-1- and HIV-1-infected individuals.
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Bet A, Maze EA, Bansal A, Sterrett S, Gross A, Graff-Dubois S, Samri A, Guihot A, Katlama C, Theodorou I, Mesnard JM, Moris A, Goepfert PA, Cardinaud S. The HIV-1 antisense protein (ASP) induces CD8 T cell responses during chronic infection. Retrovirology 2015; 12:15. [PMID: 25809376 PMCID: PMC4335690 DOI: 10.1186/s12977-015-0135-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 01/05/2015] [Indexed: 12/18/2022] Open
Abstract
Background CD8+ T cells recognize HIV-1 epitopes translated from a gene’s primary reading frame (F1) and any one of its five alternative reading frames (ARFs) in the forward (F2, F3) or reverse (R1-3) directions. The 3’ end of HIV-1’s proviral coding strand contains a conserved sequence that is directly overlapping but antiparallel to the env gene (ARF R2) and encodes for a putative antisense HIV-1 protein called ASP. ASP expression has been demonstrated in vitro using HIV-transfected cell lines or infected cells. Although antibodies to ASP were previously detected in patient sera, T cell recognition of ASP-derived epitopes has not been evaluated. We therefore investigated the ex vivo and in vitro induction of ASP-specific T cell responses as a measure of immune recognition and protein expression during HIV-1 infection. Results A panel of overlapping peptides was initially designed from the full-length ASP sequence to perform a global assessment of T cell responses. Recognition of ASP-derived antigens was evaluated in an IFN-γELISpot assay using PBMCs from HIV-1 seropositive and seronegative individuals. Eight of 25 patients had positive responses to ASP antigens and none of the seronegative donors responded. As a complimentary approach, a second set of antigens was designed using HLA-I binding motifs and affinities. Two ASP-derived peptides with high predicted binding affinities for HLA-A*02 (ASP-YL9) and HLA-B*07 (ASP-TL10) were tested using PBMCs from HIV-1 seropositive and seronegative individuals who expressed the matching HLA-I-restricting allele. We found that HLA-I-restricted ASP peptides were only recognized by CD8+ T cells from patients with the relevant HLA-I and did not induce responses in any of the seronegative donors or patients who do not express the restrictive HLA alleles. Further, ASP-YL9-specific CD8+ T cells had functional profiles that were similar to a previously described HLA-A*02-restricted epitope (Gag-SL9). Specific recognition of ASP-YL9 by CD8+ T cells was also demonstrated by tetramer staining using cells from an HLA-A*02 HIV-infected patient. Conclusion Our results provide the first description of CD8+ T cell-mediated immune responses to ASP in HIV-1-infected patients, demonstrating that ASP is expressed during infection. Our identification of epitopes within ASP has implications for designing HIV vaccines. Electronic supplementary material The online version of this article (doi:10.1186/s12977-015-0135-y) contains supplementary material, which is available to authorized users.
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Construction of a reporter vector for analysis of bidirectional transcriptional activity of retrovirus LTR. Plasmid 2014; 74:45-51. [PMID: 24971710 DOI: 10.1016/j.plasmid.2014.06.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 06/10/2014] [Accepted: 06/16/2014] [Indexed: 01/09/2023]
Abstract
To study the transcriptional activity of the HIV-1 LTR, we constructed a vector containing Renilla and Firefly luciferase genes under the control of the LTR (wild-type or mutated version) and oriented in a manner that allowed them to be transcribed in opposite directions. We found that the HIV-1 LTR acted as a bidirectional promoter, which activity was controlled by NF-κB- and Sp1-binding sites in both orientations. We next analyzed with this reporter vector the bidirectional promoter activity of the HTLV-1 LTR and showed that this LTR also possessed a bidirectional transcriptional activity. Interestingly, Sp1-binding elements were also involved in the control of HTLV-1 bidirectional transcription. Moreover, both retroviral trans-activators, Tat and Tax, could preferentially activate sense transcription with no or limited effect on the extent of antisense transcription. We also cloned into this plasmid the MLV LTR and found that the LTR of a simple retrovirus also possessed bidirectional transcriptional activity. This reporter vector represents a powerful tool to analyze the bidirectional transcriptional activity of retrovirus LTRs.
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Abstract
PURPOSE OF REVIEW One of the seven key scientific priorities identified in the road map on HIV cure research is to 'determine the host mechanisms that control HIV replication in the absence of therapy'. This review summarizes the recent work in genomics and in epigenetic control of viral replication that is relevant for this mission. RECENT FINDINGS New technologies allow the joint analysis of host and viral transcripts. They identify the patterns of antisense transcription of the viral genome and its role in gene regulation. High-throughput studies facilitate the assessment of integration at the genome scale. Integration site, orientation and host genomic context modulate the transcription and should also be assessed at the level of single cells. The various models of latency in primary cells can be followed using dynamic study designs to acquire transcriptome and proteome data of the process of entry, maintenance and reactivation of latency. Dynamic studies can be applied to the study of transcription factors and chromatin modifications in latency and upon reactivation. SUMMARY The convergence of primary cell models of latency, new high-throughput quantitative technologies applied to the study of time series and the identification of compounds that reactivate viral transcription bring unprecedented precision to the study of viral latency.
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Detection of the HIV-1 minus-strand-encoded antisense protein and its association with autophagy. J Virol 2013; 87:5089-105. [PMID: 23427159 DOI: 10.1128/jvi.00225-13] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
HIV-1 proteins are synthesized from a single transcript in an unspliced form or following splicing, but the existence of an antisense protein (ASP) expressed from an antisense polyadenylated transcript has been suggested. Difficulties linked to the detection of this protein in mammalian cells led us to codon optimize its cDNA. Codon-optimized ASP was indeed efficiently detected in various transfected cell lines following flow cytometry and confocal microscopy analyses. Western blot analyses also led to the detection of optimized ASP in transfected cells but also provided evidence of its instability and high multimerization potential. ASP was mainly distributed in the cytoplasm in a punctate manner, which was reminiscent of autophagosomes. In agreement with this observation, a significant increase in ASP-positive cells and loss of its punctate distribution was observed in transfected cells when autophagy was inhibited at early steps. Induction of autophagy was confirmed by Western blot analyses that showed an ASP-mediated increase in levels of LC3b-II and Beclin 1, as well as colocalization and interaction between ASP and LC3. Interestingly, Myc-tagged ASP was detected in the context of proviral DNA following autophagy inhibition with a concomitant increase in the level and punctate distribution of LC3b-II. Finally, 3-methyladenine treatment of transfected or infected U937 cells decreased extracellular p24 levels in wild-type proviral DNA and to a much lesser extent in ASP-mutated proviral DNA. This study provides the first detection of ASP in mammalian cells by Western blotting. ASP-induced autophagy might explain the inherent difficulty in detecting this viral protein and might justify its presumed low abundance in infected cells.
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