1
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Hasanshahi Z, Dehghani B, Hashempour A. Interaction Between Vpx and SAMHD1, Vital for SAMHD1 Inhibition. AIDS Res Hum Retroviruses 2024; 40:384-392. [PMID: 38084955 DOI: 10.1089/aid.2023.0052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2023] Open
Abstract
It was confirmed that the sterile alpha motif and HD domain 1 (SAMHD1) limits human immunodeficiency virus type 1 (HIV-1) replication. In contrast, viral protein x (Vpx) in HIV-2 and some simian immunodeficiency viruses can counteract this effect. The possible interaction between SAMHD1 and Vpx was suggested by previous studies; however, there are no data to confirm this interaction. Therefore, this study aimed to study the interaction between two proteins and the properties of Vpx protein for the first time using bioinformatic tools. Vpx and SAMHD1 sequences were obtained from the National Center for Biotechnology Information GenBank. Several software were used to define Vpx properties and the interaction between Vpx and different SAMHD1 isoforms. Our findings indicated the difference in interaction sites among different Vpx. However, in all Vpx proteins, this region is from amino acids 4 to 90. In addition, two regions (26-31 and 134-139) and two amino acids 425 and 429 in SAMHD1 are vital in the possible interaction. In addition, our analysis determined the physicochemical and immunological properties of the Vpx. Considering all factors, this study could confirm that Vpx interacts with SAMHD1, which could inhibit SAMHD1. Moreover, our findings can pave the way for future studies to express and purify Vpx in the laboratory and study this protein in vitro.
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Affiliation(s)
- Zahra Hasanshahi
- HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Behzad Dehghani
- HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Ava Hashempour
- HIV/AIDS Research Center, Institute of Health, Shiraz University of Medical Sciences, Shiraz, Iran
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2
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Solomon M, Liang C. Pseudotyped Viruses for Retroviruses. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1407:61-84. [PMID: 36920692 DOI: 10.1007/978-981-99-0113-5_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
Since the discovery of retroviruses, their genome and replication strategies have been extensively studied, leading to the discovery of several unique features that make them invaluable vectors for virus pseudotyping, gene delivery, and gene therapy. Notably, retroviral vectors enable the integration of a gene of interest into the host genome, they can be used to stably transduce both dividing and nondividing cells, and they can deliver relatively large genes. Today, retroviral vectors are commonly used for many research applications and have become an active tool in gene therapy and clinical trials. This chapter will discuss the important features of the retroviral genome and replication cycle that are crucial for the development of retroviral vectors, the different retrovirus-based vector systems that are commonly used, and finally the research and clinical applications of retroviral vectors.
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Affiliation(s)
- Magan Solomon
- Lady Davis Institute, Jewish General Hospital, McGill Centre for Viral Diseases, Montreal, QC, Canada.,Department of Medicine, McGill University, Montreal, QC, Canada
| | - Chen Liang
- Lady Davis Institute, Jewish General Hospital, McGill Centre for Viral Diseases, Montreal, QC, Canada. .,Department of Medicine, McGill University, Montreal, QC, Canada.
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3
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Barrett B, Nguyen DH, Xu J, Guo K, Shetty S, Jones ST, Mickens KL, Shepard C, Roers A, Behrendt R, Wu L, Kim B, Santiago ML. SAMHD1 Promotes the Antiretroviral Adaptive Immune Response in Mice Exposed to Lipopolysaccharide. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:444-453. [PMID: 34893529 DOI: 10.4049/jimmunol.2001389] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 11/08/2021] [Indexed: 12/13/2022]
Abstract
SAMHD1 is a potent HIV-1 restriction factor that blocks reverse transcription in monocytes, dendritic cells and resting CD4+ T cells by decreasing intracellular dNTP pools. However, SAMHD1 may diminish innate immune sensing and Ag presentation, resulting in a weaker adaptive immune response. To date, the role of SAMHD1 on antiretroviral immunity remains unclear, as mouse SAMHD1 had no impact on murine retrovirus replication in prior in vivo studies. Here, we show that SAMHD1 significantly inhibits acute Friend retrovirus infection in mice. Pretreatment with LPS, a significant driver of inflammation during HIV-1 infection, further unmasked a role for SAMHD1 in influencing immune responses. LPS treatment in vivo doubled the intracellular dNTP levels in immune compartments of SAMHD1 knockout but not wild-type mice. SAMHD1 knockout mice exhibited higher plasma infectious viremia and proviral DNA loads than wild-type mice at 7 d postinfection (dpi), and proviral loads inversely correlated with a stronger CD8+ T cell response. SAMHD1 deficiency was also associated with weaker NK, CD4+ T and CD8+ T cell responses by 14 dpi and weaker neutralizing Ab responses by 28 dpi. Intriguingly, SAMHD1 influenced these cell-mediated immune (14 dpi) and neutralizing Ab (28 dpi) responses in male but not female mice. Our findings formally demonstrate SAMHD1 as an antiretroviral factor in vivo that could promote adaptive immune responses in a sex-dependent manner. The requirement for LPS to unravel the SAMHD1 immunological phenotype suggests that comorbidities associated with a "leaky" gut barrier may influence the antiviral function of SAMHD1 in vivo.
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Affiliation(s)
- BradleyS Barrett
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO
| | - David H Nguyen
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO
| | - Joella Xu
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA
| | - Kejun Guo
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO
| | - Shravida Shetty
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO
| | - Sean T Jones
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO.,Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO
| | - Kaylee L Mickens
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO.,Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO
| | - Caitlin Shepard
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA
| | - Axel Roers
- Institute for Immunology, Faculty of Medicine, Technical University Dresden, Dresden, Germany
| | - Rayk Behrendt
- Institute for Immunology, Faculty of Medicine, Technical University Dresden, Dresden, Germany
| | - Li Wu
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA; and
| | - Baek Kim
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, GA.,Center for Drug Discovery, Children's Healthcare of Atlanta, Atlanta, GA
| | - Mario L Santiago
- Department of Medicine, University of Colorado School of Medicine, Aurora, CO; .,Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO
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4
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Shimagaki K, Koga R, Fujino H, Ahagon A, Tateishi H, Otsuka M, Yamaguchi Y, Fujita M. The stability of HIV-2 Vpx and Vpr proteins is regulated by the presence or absence of zinc-binding sites and poly-proline motifs with distinct roles. J Gen Virol 2020; 101:997-1007. [PMID: 32553018 DOI: 10.1099/jgv.0.001456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Vpx and Vpr proteins of human immunodeficiency virus type 2 (HIV-2) are important for virus replication. Although these proteins are homologous, Vpx is expressed at much higher levels than Vpr. Previous studies demonstrated that this difference results from the presence of an HHCC zinc-binding site in Vpx that is absent in Vpr. Vpx has another unique region, a poly-proline motif (PPM) of seven consecutive prolines at the C-terminus. Using PPM point mutants of Vpx, this study demonstrated that these seven consecutive prolines are critical for suppressing proteasome degradation of Vpx in the absence of Gag. Both the PPM and the zinc-binding site stabilize Vpx but do so via different mechanisms. PPM and zinc-binding site mutants overexpressed in Escherichia coli aggregated readily, indicating that these motifs normally prevent exposure of the hydrophobic region outside the structure. Furthermore, introduction of the zinc-binding site and the PPM into Vpr increased the level of Vpr expression so that it was as high as that of Vpx. Intriguingly, HIV-2 has evolved to express Vpx at high levels and Vpr at low levels based on the presence and absence of these two motifs with distinct roles.
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Affiliation(s)
- Kazunori Shimagaki
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Ryoko Koga
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Haruna Fujino
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Ami Ahagon
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Hiroshi Tateishi
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Masami Otsuka
- Science Farm Ltd, Kumamoto, Japan.,Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | | | - Mikako Fujita
- Medicinal and Biological Chemistry Science Farm Joint Research Laboratory, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
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5
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Singh SP, Raja S, Mahalingam S. Viral protein X unlocks the nuclear pore complex through a human Nup153-dependent pathway to promote nuclear translocation of the lentiviral genome. Mol Biol Cell 2020; 31:304-317. [PMID: 31913756 PMCID: PMC7183765 DOI: 10.1091/mbc.e19-08-0438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Simian immunodeficiency virus (SIV) and human immunodeficiency virus 2 (HIV-2) display unique ability to infect nondividing target cells. Viral protein X (Vpx) of HIV-2/SIV is known to be involved in the nuclear import of viral genome in nondividing cells, but the mechanism remains poorly understood. In the present investigation for the first time we provide evidence that Vpx of SIVsmPBj1.9 physically interacts with human nucleoporin 153 (Nup153), which is known to provide a docking site for protein-cargo complexes at the nuclear pore complex (NPC). Results from superresolution-structured illumination microscopy studies reveal that Vpx interaction with NPC-associated Nup153 is critical for its efficient nuclear translocation. Virion-associated MAPK/ERK-2-mediated phosphorylation of Vpx plays a critical role in its interaction with human Nup153 and this interaction was found to be evolutionarily conserved in various SIV isolates and HIV-2. Interestingly, MAPK/ERK-2 packaging defective SIV failed to promote the efficient nuclear import of viral genome and suggests that MAPK/ERK-2-mediated Vpx phosphorylation is important for its interaction with Nup153, which is critical for lentiviruses to establish infection in nondividing target cells. Together, our data elucidate the mechanism by which Vpx orchestrates the challenging task of nuclear translocation of HIV-2/SIV genome in nondividing target cells.
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Affiliation(s)
- Satya Prakash Singh
- Laboratory of Molecular Cell Biology, Indian Institute of Technology-Madras, Chennai 600 036, India
| | - Sebastian Raja
- Laboratory of Molecular Cell Biology, Indian Institute of Technology-Madras, Chennai 600 036, India
| | - Sundarasamy Mahalingam
- Laboratory of Molecular Cell Biology, Indian Institute of Technology-Madras, Chennai 600 036, India.,National Cancer Tissue Biobank, Bhupat and Jyoti Mehta School of Biosciences, Department of Biotechnology, Indian Institute of Technology-Madras, Chennai 600 036, India
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6
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Low-Bias RNA Sequencing of the HIV-2 Genome from Blood Plasma. J Virol 2018; 93:JVI.00677-18. [PMID: 30333167 PMCID: PMC6288329 DOI: 10.1128/jvi.00677-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 09/14/2018] [Indexed: 11/20/2022] Open
Abstract
Accurate determination of the genetic diversity present in the HIV quasispecies is critical for the development of a preventative vaccine: in particular, little is known about viral genetic diversity for the second type of HIV, HIV-2. A better understanding of HIV-2 biology is relevant to the HIV vaccine field because a substantial proportion of infected people experience long-term viral control, and prior HIV-2 infection has been associated with slower HIV-1 disease progression in coinfected subjects. The majority of traditional and next-generation sequencing methods have relied on target amplification prior to sequencing, introducing biases that may obscure the true signals of diversity in the viral population. Additionally, target enrichment through PCR requires a priori sequence knowledge, which is lacking for HIV-2. Therefore, a target enrichment free method of library preparation would be valuable for the field. We applied an RNA shotgun sequencing (RNA-Seq) method without PCR amplification to cultured viral stocks and patient plasma samples from HIV-2-infected individuals. Libraries generated from total plasma RNA were analyzed with a two-step pipeline: (i) de novo genome assembly, followed by (ii) read remapping. By this approach, whole-genome sequences were generated with a 28× to 67× mean depth of coverage. Assembled reads showed a low level of GC bias, and comparison of the genome diversities at the intrahost level showed low diversity in the accessory gene vpx in all patients. Our study demonstrates that RNA-Seq is a feasible full-genome de novo sequencing method for blood plasma samples collected from HIV-2-infected individuals.IMPORTANCE An accurate picture of viral genetic diversity is critical for the development of a globally effective HIV vaccine. However, sequencing strategies are often complicated by target enrichment prior to sequencing, introducing biases that can distort variant frequencies, which are not easily corrected for in downstream analyses. Additionally, detailed a priori sequence knowledge is needed to inform robust primer design when employing PCR amplification, a factor that is often lacking when working with tropical diseases localized in developing countries. Previous work has demonstrated that direct RNA shotgun sequencing (RNA-Seq) can be used to circumvent these issues for hepatitis C virus (HCV) and norovirus. We applied RNA-Seq to total RNA extracted from HIV-2 blood plasma samples, demonstrating the applicability of this technique to HIV-2 and allowing us to generate a dynamic picture of genetic diversity over the whole genome of HIV-2 in the context of low-bias sequencing.
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7
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Plitnik T, Sharkey ME, Mahboubi B, Kim B, Stevenson M. Incomplete Suppression of HIV-1 by SAMHD1 Permits Efficient Macrophage Infection. Pathog Immun 2018; 3:197-223. [PMID: 30656243 PMCID: PMC6333473 DOI: 10.20411/pai.v3i2.263] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background: Sterile alpha motif and histidine/aspartic acid domain-containing protein (SAMHD1) is a dNTP triphosphorylase that reduces cellular dNTP levels in non-dividing cells, such as macrophages. Since dNTPs are required for reverse transcription, HIV-2 and most SIVs encode a Vpx protein that promotes proteasomal degradation of SAMHD1. It is unclear how HIV-1, which does not appear to harbor a SAMHD1 escape mechanism, is able to infect macrophages in the face of SAMHD1 restriction. Methods: To assess whether HIV-1 had a mechanism to negate SAMHD1 activity, we compared SAMHD1 and dNTP levels in macrophages infected by HIV-1 and SIV. We examined whether macrophages infected by HIV-1 still harbored antiviral levels of SAMHD1 by assessing their susceptibility to superinfection by vpx-deleted SIV. Finally, to assess whether HIV-1 reverse transcriptase (RT) has adapted to a low dNTP environment, we evaluated SAMHD1 sensitivity of chimeric HIV-1 and SIV variants in which the RT regions were functionally exchanged. Results: Here, we demonstrate that HIV-1 efficiently infects macrophages without modulating SAMHD1 activity or cellular dNTP levels, and that macrophages permissive to HIV-1 infection remained refractory to superinfection by vpx-deleted SIV. Furthermore, through the use of chimeric HIV/SIV, we demonstrate that the differential sensitivity of HIV-1 and SIV to SAMHD1 restriction is not dictated by RT. Conclusions: Our study reveals fundamental differences between HIV-1 and SIV in the strategy used to evade restriction by SAMHD1 and suggests a degree of resistance of HIV-1 to the antiviral environment created by SAMHD1. Understanding how these cellular restrictions antagonize viral replication will be important for the design of novel antiviral strategies.
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Affiliation(s)
- Timothy Plitnik
- Department of Microbiology & Immunology; Miller School of Medicine, University of Miami; Miami, Florida
| | - Mark E Sharkey
- Department of Medicine; Miller School of Medicine, University of Miami; Miami, Florida
| | - Bijan Mahboubi
- Department of Pediatrics, Emory University; Atlanta, Georgia.,Center for Drug Discovery, Children's Healthcare of Atlanta; Atlanta, Georgia
| | - Baek Kim
- Department of Pediatrics, Emory University; Atlanta, Georgia.,Center for Drug Discovery, Children's Healthcare of Atlanta; Atlanta, Georgia.,Department of Pharmacy, Kyung-Hee University; Seoul; South Korea
| | - Mario Stevenson
- Department of Microbiology & Immunology; Miller School of Medicine, University of Miami; Miami, Florida.,Department of Medicine; Miller School of Medicine, University of Miami; Miami, Florida
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8
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HIV-2/SIV viral protein X counteracts HUSH repressor complex. Nat Microbiol 2018; 3:891-897. [PMID: 29891865 DOI: 10.1038/s41564-018-0179-6] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 05/16/2018] [Indexed: 11/08/2022]
Abstract
To evade host immune defences, human immunodeficiency viruses 1 and 2 (HIV-1 and HIV-2) have evolved auxiliary proteins that target cell restriction factors. Viral protein X (Vpx) from the HIV-2/SIVsmm lineage enhances viral infection by antagonizing SAMHD1 (refs 1,2), but this antagonism is not sufficient to explain all Vpx phenotypes. Here, through a proteomic screen, we identified another Vpx target-HUSH (TASOR, MPP8 and periphilin)-a complex involved in position-effect variegation3. HUSH downregulation by Vpx is observed in primary cells and HIV-2-infected cells. Vpx binds HUSH and induces its proteasomal degradation through the recruitment of the DCAF1 ubiquitin ligase adaptor, independently from SAMHD1 antagonism. As a consequence, Vpx is able to reactivate HIV latent proviruses, unlike Vpx mutants, which are unable to induce HUSH degradation. Although antagonism of human HUSH is not conserved among all lentiviral lineages including HIV-1, it is a feature of viral protein R (Vpr) from simian immunodeficiency viruses (SIVs) of African green monkeys and from the divergent SIV of l'Hoest's monkey, arguing in favour of an ancient lentiviral species-specific vpx/vpr gene function. Altogether, our results suggest the HUSH complex as a restriction factor, active in primary CD4+ T cells and counteracted by Vpx, therefore providing a molecular link between intrinsic immunity and epigenetic control.
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9
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Bakir TM. The role of SAMHD1 expression and its relation to HIV-2 (Vpx) gene production. Saudi Pharm J 2018; 26:903-908. [PMID: 30202235 PMCID: PMC6128726 DOI: 10.1016/j.jsps.2018.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 03/10/2018] [Indexed: 11/21/2022] Open
Abstract
SAMHD1 (sterile alpha motif and HD domain 1) is a protein that is found in myeloid cells, which restricts HIV1 replication. It depletes the de-oxy-nucleoside tri-phosphate (dNTPs) pool needed for a viral cDNA synthesis leading to inhibition of viral replication inside the cells. However, it does not restrict HIV2 replication in myeloid cells due to the presence of viral Vpx protein. Vpx is a virion-associated protein which augments viral infectivity and it only exists in HIV2 and it has been recently shown in Simian Immunodeficiency Virus (SIV) and which can induce degradation of SAMHD1 protein. This increases the amount of dNTPs for viral reverse transcription in cytoplasm and HIV infection. HIV2 reverse transcription is believed to be less active than HIV1 and this could be the reason for the absence of Vpx from HIV1. Protein expression and interaction between Vpx and SAMHD1 remains unclear. The interaction of SAMHD1 and HIV2-VPx patients' cells can be considered as a first step to help in the development for more effective anti-HIV drugs and possible novel intervention therapy in the future. Present review article provides comprehensive insights on the above issue. We performed a comprehensive literature search in the bibliographic database “Pubmed,” looking at studies discussing the SAMHDI and Vpx interactions.
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10
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Koga R, Yamamoto M, Ciftci HI, Otsuka M, Fujita M. Introduction of H2C2-type zinc-binding residues into HIV-2 Vpr increases its expression level. FEBS Open Bio 2018; 8:146-153. [PMID: 29321964 PMCID: PMC5757179 DOI: 10.1002/2211-5463.12358] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 11/11/2017] [Accepted: 11/22/2017] [Indexed: 12/21/2022] Open
Abstract
Human immunodeficiency virus type 2 has two structurally similar proteins, Vpx and Vpr. Vpx degrades the host anti-viral protein SAMHD1 and is expressed at high levels, while Vpr is responsible for cell cycle arrest and is expressed at much lower levels. We constructed a Vpr mutant with a high level of expression by replacing the amino acids HHCR/HHCH with a putative H2C2-type zinc-binding site that is carried by Vpx. Our finding suggests that during the evolution of Vpr and Vpx, zinc-binding likely became a mechanism for regulating their expression levels.
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Affiliation(s)
- Ryoko Koga
- Department of Bioorganic Medicinal Chemistry Faculty of Life Sciences Kumamoto University Japan
| | - Minami Yamamoto
- Department of Bioorganic Medicinal Chemistry Faculty of Life Sciences Kumamoto University Japan
| | - Halil Ibrahim Ciftci
- Department of Bioorganic Medicinal Chemistry Faculty of Life Sciences Kumamoto University Japan
| | - Masami Otsuka
- Department of Bioorganic Medicinal Chemistry Faculty of Life Sciences Kumamoto University Japan
| | - Mikako Fujita
- Research Institute for Drug Discovery School of Pharmacy Kumamoto University Japan
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11
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Yamamoto M, Koga R, Fujino H, Shimagaki K, Ciftci HI, Kamo M, Tateishi H, Otsuka M, Fujita M. Zinc-binding site of human immunodeficiency virus 2 Vpx prevents instability and dysfunction of the protein. J Gen Virol 2017; 98:275-283. [DOI: 10.1099/jgv.0.000701] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Minami Yamamoto
- Department of Bioorganic Medicinal Chemistry, Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Ryoko Koga
- Department of Bioorganic Medicinal Chemistry, Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Haruna Fujino
- Department of Bioorganic Medicinal Chemistry, Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Kazunori Shimagaki
- Department of Bioorganic Medicinal Chemistry, Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Halil Ibrahim Ciftci
- Department of Bioorganic Medicinal Chemistry, Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Masahiro Kamo
- Department of Bioorganic Medicinal Chemistry, Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Hiroshi Tateishi
- Department of Bioorganic Medicinal Chemistry, Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Masami Otsuka
- Department of Bioorganic Medicinal Chemistry, Faculty of Life Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
| | - Mikako Fujita
- Research Institute for Drug Discovery, School of Pharmacy, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto 862-0973, Japan
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12
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Sakai Y, Miyake A, Doi N, Sasada H, Miyazaki Y, Adachi A, Nomaguchi M. Expression Profiles of Vpx/Vpr Proteins Are Co-related with the Primate Lentiviral Lineage. Front Microbiol 2016; 7:1211. [PMID: 27536295 PMCID: PMC4971069 DOI: 10.3389/fmicb.2016.01211] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 07/20/2016] [Indexed: 01/03/2023] Open
Abstract
Viruses of human immunodeficiency virus type 2 (HIV-2) and some simian immunodeficiency virus (SIV) lineages carry a unique accessory protein called Vpx. Vpx is essential or critical for viral replication in natural target cells such as macrophages and T lymphocytes. We have previously shown that a poly-proline motif (PPM) located at the C-terminal region of Vpx is required for its efficient expression in two strains of HIV-2 and SIVmac, and that the Vpx expression levels of the two clones are significantly different. Notably, the PPM sequence is conserved and confined to Vpx and Vpr proteins derived from certain lineages of HIV-2/SIVs. In this study, Vpx/Vpr proteins from diverse primate lentiviral lineages were experimentally and phylogenetically analyzed to obtain the general expression picture in cells. While both the level and PPM-dependency of Vpx/Vpr expression in transfected cells varied among viral strains, each viral group, based on Vpx/Vpr amino acid sequences, was found to exhibit a characteristic expression profile. Moreover, phylogenetic tree analyses on Gag and Vpx/Vpr proteins gave essentially the same results. Taken together, our study described here suggests that each primate lentiviral lineage may have developed a unique expression pattern of Vpx/Vpr proteins for adaptation to its hostile cellular and species environments in the process of viral evolution.
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Affiliation(s)
- Yosuke Sakai
- Department of Microbiology, Tokushima University Graduate School of Medical Science Tokushima, Japan
| | - Ariko Miyake
- Laboratory of Molecular Immunology and Infectious Disease, Joint Faculty of Veterinary Medicine, Yamaguchi University Yamaguchi, Japan
| | - Naoya Doi
- Department of Microbiology, Tokushima University Graduate School of Medical Science Tokushima, Japan
| | - Hikari Sasada
- Department of Microbiology, Tokushima University Graduate School of Medical Science Tokushima, Japan
| | - Yasuyuki Miyazaki
- Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science Tokyo, Japan
| | - Akio Adachi
- Department of Microbiology, Tokushima University Graduate School of Medical Science Tokushima, Japan
| | - Masako Nomaguchi
- Department of Microbiology, Tokushima University Graduate School of Medical Science Tokushima, Japan
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13
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Maelfait J, Bridgeman A, Benlahrech A, Cursi C, Rehwinkel J. Restriction by SAMHD1 Limits cGAS/STING-Dependent Innate and Adaptive Immune Responses to HIV-1. Cell Rep 2016; 16:1492-1501. [PMID: 27477283 PMCID: PMC4978700 DOI: 10.1016/j.celrep.2016.07.002] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 05/20/2016] [Accepted: 07/01/2016] [Indexed: 01/08/2023] Open
Abstract
SAMHD1 is a restriction factor for HIV-1 infection. SAMHD1 mutations cause the autoinflammatory Aicardi-Goutières syndrome that is characterized by chronic type I interferon (IFN) secretion. We show that the spontaneous IFN response in SAMHD1-deficient cells and mice requires the cGAS/STING cytosolic DNA-sensing pathway. We provide genetic evidence that cell-autonomous control of lentivirus infection in myeloid cells by SAMHD1 limits virus-induced production of IFNs and the induction of co-stimulatory markers. This program of myeloid cell activation required reverse transcription, cGAS and STING, and signaling through the IFN receptor. Furthermore, SAMHD1 reduced the induction of virus-specific cytotoxic T cells in vivo. Therefore, virus restriction by SAMHD1 limits the magnitude of IFN and T cell responses. This demonstrates a competition between cell-autonomous virus control and subsequent innate and adaptive immune responses, a concept with important implications for the treatment of infection. Spontaneous IFN production in SAMHD1-deficient cells requires cGAS and STING During HIV-1 infection, SAMHD1 limits activation of myeloid cells cGAS and STING detect HIV-1 infection in SAMHD1-deficient cells and induce IFN SAMHD1 prevents virus-specific CD8 T cell responses in vivo
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Affiliation(s)
- Jonathan Maelfait
- Medical Research Council Human Immunology Unit, Weatherall Institute of Molecular Medicine and Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Anne Bridgeman
- Medical Research Council Human Immunology Unit, Weatherall Institute of Molecular Medicine and Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Adel Benlahrech
- Medical Research Council Human Immunology Unit, Weatherall Institute of Molecular Medicine and Nuffield Department of Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Chiara Cursi
- Medical Research Council Human Immunology Unit, Weatherall Institute of Molecular Medicine and Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Jan Rehwinkel
- Medical Research Council Human Immunology Unit, Weatherall Institute of Molecular Medicine and Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DS, UK.
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14
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Fujita M. Commentary: MARCH8 Inhibits HIV-1 Infection by Reducing Virion Incorporation of Envelope Glycoproteins. Front Microbiol 2016; 7:254. [PMID: 26941737 PMCID: PMC4764732 DOI: 10.3389/fmicb.2016.00254] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Accepted: 02/15/2016] [Indexed: 11/13/2022] Open
Affiliation(s)
- Mikako Fujita
- Research Institute for Drug Discovery, School of Pharmacy, Kumamoto University Kumamoto, Japan
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15
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Hollenbaugh JA, Schader SM, Schinazi RF, Kim B. Differential regulatory activities of viral protein X for anti-viral efficacy of nucleos(t)ide reverse transcriptase inhibitors in monocyte-derived macrophages and activated CD4(+) T cells. Virology 2015; 485:313-21. [PMID: 26319213 PMCID: PMC4619155 DOI: 10.1016/j.virol.2015.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 07/27/2015] [Accepted: 08/08/2015] [Indexed: 01/05/2023]
Abstract
Vpx encoded by HIV-2 and SIVsm enhances retroviral reverse transcription in macrophages in vitro by mediating the degradation of the host SAMHD1 protein that hydrolyzes dNTPs and by elevating cellular dNTP levels. Here we employed RT-SHIV constructs (SIV encoding HIV-1 RT) to investigate the contribution of Vpx to the potency of NRTIs, which compete against dNTPs, in monocyte-derived macrophages (MDMs) and activated CD4(+) T cells. Relative to HIV-1, both SIV and RT-SHIV exhibited reduced sensitivities to AZT, 3TC and TDF in MDMs but not in activated CD4(+) T cells. However, when SIV and RT-SHIV constructs not coding for Vpx were utilized, we observed greater sensitivities to all NRTIs tested using activated CD4(+) T cells relative to the Vpx-coding counterparts. This latter phenomenon was observed for AZT only when using MDMs. Our data suggest that Vpx in RT-SHIVs may underestimate the antiviral efficacy of NRTIs in a cell type dependent manner.
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Affiliation(s)
- Joseph A Hollenbaugh
- Center for Drug Discovery, Department of Pediatrics, Emory University, Atlanta, GA, USA
| | - Susan M Schader
- Center for Drug Discovery, Department of Pediatrics, Emory University, Atlanta, GA, USA
| | - Raymond F Schinazi
- Center for Drug Discovery, Department of Pediatrics, Emory University, Atlanta, GA, USA; Veterans Affairs Medical Center, Atlanta, GA, USA
| | - Baek Kim
- Center for Drug Discovery, Department of Pediatrics, Emory University, Atlanta, GA, USA; College of Pharmacy, Kyung Hee University, Seoul, South Korea.
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16
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Shingai M, Welbourn S, Brenchley JM, Acharya P, Miyagi E, Plishka RJ, Buckler-White A, Kwong PD, Nishimura Y, Strebel K, Martin MA. The Expression of Functional Vpx during Pathogenic SIVmac Infections of Rhesus Macaques Suppresses SAMHD1 in CD4+ Memory T Cells. PLoS Pathog 2015; 11:e1004928. [PMID: 25996507 PMCID: PMC4440783 DOI: 10.1371/journal.ppat.1004928] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 05/01/2015] [Indexed: 11/25/2022] Open
Abstract
For nearly 20 years, the principal biological function of the HIV-2/SIV Vpx gene has been thought to be required for optimal virus replication in myeloid cells. Mechanistically, this Vpx activity was recently reported to involve the degradation of Sterile Alpha Motif and HD domain-containing protein 1 (SAMHD1) in this cell lineage. Here we show that when macaques were inoculated with either the T cell tropic SIVmac239 or the macrophage tropic SIVmac316 carrying a Vpx point mutation that abrogates the recruitment of DCAF1 and the ensuing degradation of endogenous SAMHD1 in cultured CD4+ T cells, virus acquisition, progeny virion production in memory CD4+ T cells during acute infection, and the maintenance of set-point viremia were greatly attenuated. Revertant viruses emerging in two animals exhibited an augmented replication phenotype in memory CD4+ T lymphocytes both in vitro and in vivo, which was associated with reduced levels of endogenous SAMHD1. These results indicate that a critical role of Vpx in vivo is to promote the degradation of SAMHD1 in memory CD4+ T lymphocytes, thereby generating high levels of plasma viremia and the induction of immunodeficiency. Primate lentiviruses, such as HIV and its SIV simian relative, encode accessory proteins that suppress cellular restriction factors interfering with efficient replication. One of these, designated Vpx, is produced in infected cells by HIV-2 and some SIV strains, which cause endemic infections in African monkeys. The primary function of Vpx has long been thought to facilitate infectivity in dendritic cells and macrophage by degrading the Sterile Alpha Motif and HD domain-containing protein 1 (SAMHD1), which restricts virus replication in these cells. Using SIVmac carrying a mutated Vpx gene with a single amino acid change that prevents it from binding to DCAF1 and subsequently mediating the degradation of SAMHD1, we show that virus infection of CD4+ T lymphocytes is markedly compromised both in vitro and in vivo. The SIV Vpx mutant is severely attenuated in establishing new infections in inoculated rhesus monkeys, in producing high levels of virus progeny, in degrading SAMHD1 in memory CD4+ T cell in infected animals, and in inducing symptomatic disease. Thus, although once considered to be only critical for optimal replication in macrophage based on earlier studies performed with cultured cells, the SIV Vpx protein is functionally important in vivo for establishing the primary infection in rhesus macaques, sustaining high levels of virus replication in CD4+ T lymphocytes, and promoting the onset of symptomatic immunodeficiency.
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Affiliation(s)
- Masashi Shingai
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Sarah Welbourn
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jason M. Brenchley
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Priyamvada Acharya
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Eri Miyagi
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Ronald J. Plishka
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Alicia Buckler-White
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Peter D. Kwong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Yoshiaki Nishimura
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Klaus Strebel
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Malcolm A. Martin
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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17
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Mutational analysis of HIV-2 Vpx shows that proline residue 109 in the poly-proline motif regulates degradation of SAMHD1. FEBS Lett 2015; 589:1505-14. [DOI: 10.1016/j.febslet.2015.04.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 04/13/2015] [Accepted: 04/21/2015] [Indexed: 11/22/2022]
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18
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Virological characterization of HIV-2 vpx gene mutants in various cell systems. Microbes Infect 2014; 16:695-701. [DOI: 10.1016/j.micinf.2014.06.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Revised: 06/13/2014] [Accepted: 06/13/2014] [Indexed: 12/24/2022]
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19
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Dendritic cell-lymphocyte cross talk downregulates host restriction factor SAMHD1 and stimulates HIV-1 replication in dendritic cells. J Virol 2014; 88:5109-21. [PMID: 24574390 DOI: 10.1128/jvi.03057-13] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
UNLABELLED Human immunodeficiency virus type 1 (HIV-1) replication in dendritic cells (DCs) is restricted by SAMHD1. This factor is counteracted by the viral protein Vpx; Vpx is found in HIV-2 and simian immunodeficiency virus (SIV) from sooty mangabeys (SIVsm) or from macaques (SIVmac) but is absent from HIV-1. We previously observed that HIV-1 replication in immature DCs is stimulated by cocultivation with primary T and B lymphocytes, suggesting that HIV-1 restriction in DCs may be overcome under coculture conditions. Here, we aimed to decipher the mechanism of SAMHD1-mediated restriction in DC-lymphocyte coculture. We found that coculture with lymphocytes downregulated SAMHD1 expression and was associated with increased HIV-1 replication in DCs. Moreover, in infected DC-T lymphocyte cocultures, DCs acquired maturation status and secreted type 1 interferon (alpha interferon [IFN-α]). The blockade of DC-lymphocyte cross talk by anti-ICAM-1 antibody markedly inhibited the stimulation of HIV-1 replication and prevented the downregulation of SAMHD1 expression in cocultured DCs. These results demonstrate that, in contrast to purified DCs, cross talk with lymphocytes downregulates SAMHD1 expression in DCs, triggering HIV-1 replication and an antiviral immune response. Therefore, HIV-1 replication and immune sensing by DCs should be investigated in more physiologically relevant models of DC/lymphocyte coculture. IMPORTANCE SAMHD1 restricts HIV-1 replication in dendritic cells (DCs). Here, we demonstrate that, in a coculture model of DCs and lymphocytes mimicking early mucosal HIV-1 infection, stimulation of HIV-1 replication in DCs is associated with downregulation of SAMHD1 expression and activation of innate immune sensing by DCs. We propose that DC-lymphocyte cross talk occurring in vivo modulates host restriction factor SAMHD1, promoting HIV-1 replication in cellular reservoirs and stimulating immune sensing.
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20
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Fujita M. Study on Molecular Function of Proteins of Human Immunodeficiency Virus. YAKUGAKU ZASSHI 2013; 133:1103-11. [DOI: 10.1248/yakushi.13-00200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Mikako Fujita
- Research Institute for Drug Discovery, School of Pharmacy, Kumamoto University
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21
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Koito A, Ishizaka Y. Retroviruses, retroelements and their restrictions. Front Microbiol 2013; 4:197. [PMID: 23874330 PMCID: PMC3710956 DOI: 10.3389/fmicb.2013.00197] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2013] [Accepted: 06/24/2013] [Indexed: 12/13/2022] Open
Affiliation(s)
- Atsushi Koito
- Department of Retrovirology and Self-Defense, Kumamoto University Kumamoto, Japan
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22
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Tsunetsugu-Yokota Y, Muhsen M. Development of human dendritic cells and their role in HIV infection: antiviral immunity versus HIV transmission. Front Microbiol 2013; 4:178. [PMID: 23847602 PMCID: PMC3705168 DOI: 10.3389/fmicb.2013.00178] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 06/13/2013] [Indexed: 11/23/2022] Open
Abstract
Although dendritic cells (DCs) represent a small cell population in the body, they have been recognized as professional antigen presenting cells and key players of both innate and acquired immunity. The recent expansion of basic knowledge concerning differentiation and function of various DC subsets will greatly help to understand the nature of protective immunity required in designing acquired immunodeficiency syndrome (AIDS) vaccines. However, human immunodeficiency virus (HIV) not only targets CD4+ T cells but also myeloid cells, including macrophages and DC. When HIV infects DC, its replication is highly restricted in DC. Nevertheless, even a low level of HIV production is sufficient to enhance HIV replication in activated CD4+ T cells, through antigen presentation activity by HIV-infected DC. Considering how antiviral immunity is initiated and memory response is maintained, such efficient DC–T cell transmission of HIV should play an important role in the disturbed immune responses associated with HIV infection. Recently, accessory proteins encoded by HIV have been shown to interact with various proteins in DC, and thereby affect DC–T cell transmission. In this review, we summarize the current understanding about DC biology, antiviral immune responses and DC restriction factors, all of which will be important issues for the development of an effective AIDS vaccine in the future.
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Abstract
Primate immunodeficiency viruses are highly specialized lentiviruses that have evolved to successfully infect and persist for the lifetime of the host. Despite encountering numerous potent antiviral factors, HIVs and SIVs are successful pathogens due to the acquisition of equally potent countermeasures in the form of accessory genes. The accessory gene Vpx encoded by HIV-2 and a subset of SIVs have a profound effect on the ability of lentiviruses to infect non-dividing cells, such as macrophages. Although most virus replication occurs in activated CD4(+) T cells, myeloid lineage cells are natural targets of infection and play a central role in virus transmission, dissemination, and persistence. However, myeloid lineage cells are poorly sensitive to lentiviral infection due partly to the high-level expression of a host protein that regulates nucleic acid metabolism named SAMHD1. Degradation of SAMHD1 is induced by Vpx to eliminate this intrinsic antiviral factor. Importantly, SAMHD1 has also been implicated as a negative regulator of the innate immune response, so the interplay between SAMHD1 and Vpx is likely to have significant consequences for virus replication, persistence, and immune control.
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Affiliation(s)
- Mark Sharkey
- University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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24
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SAMHD1 restricts HIV-1 cell-to-cell transmission and limits immune detection in monocyte-derived dendritic cells. J Virol 2012; 87:2846-56. [PMID: 23269793 DOI: 10.1128/jvi.02514-12] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SAMHD1 is a viral restriction factor expressed in dendritic cells and other cells, inhibiting infection by cell-free human immunodeficiency virus type 1 (HIV-1) particles. SAMHD1 depletes the intracellular pool of deoxynucleoside triphosphates, thus impairing HIV-1 reverse transcription and productive infection in noncycling cells. The Vpx protein from HIV-2 or simian immunodeficiency virus (SIVsm/SIVmac) antagonizes the effect of SAMHD1 by triggering its degradation. A large part of HIV-1 spread occurs through direct contacts between infected cells and bystander target cells. Here, we asked whether SAMHD1 impairs direct HIV-1 transmission from infected T lymphocytes to monocyte-derived dendritic cells (MDDCs). HIV-1-infected lymphocytes were cocultivated with MDDCs that have been pretreated or not with Vpx or with small interfering RNA against SAMHD1. We show that in the cocultures, SAMHD1 significantly inhibits productive cell-to-cell transmission to target MDDCs and prevents the type I interferon response and expression of the interferon-stimulated gene MxA. Therefore, SAMHD1, by controlling the sensitivity of MDDCs to HIV-1 infection during intercellular contacts, impacts their ability to sense the virus and to trigger an innate immune response.
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