Localization of Viral protein X in Simian Immunodeficiency Virus Macaque Strain and Analysis of its Packaging Requirements

The block toward human immunodeficiency virus type 1 (HIV-1) infection of dendritic cells (DCs) can be relieved by Vpx (viral protein X), which degrades sterile alpha motif-hydroxylase domain 1 (SAMHD1) or by exogenously added deoxynucleosides (dNs), lending support to the hypothesis that SAMHD1 acts by limiting deoxynucleoside triphosphates (dNTPs). This notion has, however, been questioned. We show that while dNs and Vpx increase the infectivity of HIV-1, only the latter restores the infectivity of a simian immunodeficiency virus of macaques variant, SIVMACΔVpx virus. This distinct behavior seems to map to CA, suggesting that species-specific CA interactors modulate infection of DCs.

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Viral protein X reduces the incorporation of mutagenic noncanonical rNTPs during lentivirus reverse transcription in macrophages

Journal of Biological Chemistry ◽

10.1074/jbc.ra119.011466 ◽

2019 ◽

Vol 295 (2) ◽

pp. 657-666

Author(s):

Adrian Oo ◽

Dong-Hyun Kim ◽

Raymond F. Schinazi ◽

Baek Kim

Keyword(s):

Simian Immunodeficiency Virus ◽

Reverse Transcription ◽

Viral Protein ◽

Cell Types ◽

Dntp Pool ◽

Sam Domain ◽

Primary Monocyte ◽

Immunodeficiency Virus ◽

Protein X ◽

Hiv 1

Unlike activated CD4+ T cells, nondividing macrophages have an extremely small dNTP pool, which restricts HIV-1 reverse transcription. However, rNTPs are equally abundant in both of these cell types and reach much higher concentrations than dNTPs. The greater difference in concentration between dNTPs and rNTPs in macrophages results in frequent misincorporation of noncanonical rNTPs during HIV-1 reverse transcription. Here, we tested whether the highly abundant SAM domain– and HD domain–containing protein 1 (SAMHD1) deoxynucleoside triphosphorylase in macrophages is responsible for frequent rNTP incorporation during HIV-1 reverse transcription. We also assessed whether Vpx (viral protein X), an accessory protein of HIV-2 and some simian immunodeficiency virus strains that targets SAMHD1 for proteolytic degradation, can counteract the rNTP incorporation. Results from biochemical simulation of HIV-1 reverse transcriptase–mediated DNA synthesis confirmed that rNTP incorporation is reduced under Vpx-mediated dNTP elevation. Using HIV-1 vector, we further demonstrated that dNTP pool elevation by Vpx or deoxynucleosides in human primary monocyte-derived macrophages reduces noncanonical rNTP incorporation during HIV-1 reverse transcription, an outcome similarly observed with the infectious HIV-1 89.6 strain. Furthermore, the simian immunodeficiency virus mac239 strain, encoding Vpx, displayed a much lower level of rNTP incorporation than its ΔVpx mutant in macrophages. Finally, the amount of rNMPs incorporated in HIV-1 proviral DNAs remained unchanged for ∼2 weeks in macrophages. These findings suggest that noncanonical rNTP incorporation is regulated by SAMHD1 in macrophages, whereas rNMPs incorporated in HIV-1 proviral DNA remain unrepaired. This suggests a potential long-term DNA damage impact of SAMHD1-mediated rNTP incorporation in macrophages.

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Presence of virion protein x (Vpx) of simian immunodeficiency virus SIVmac 251 in target cells in vivo

Journal of Medical Primatology ◽

10.1111/j.1600-0684.1995.tb00142.x ◽

1995 ◽

Vol 24 (1) ◽

pp. 35-42 ◽

Cited By ~ 1

Author(s):

Yury Persidsky ◽

Vladimir Liska ◽

Thierry Huss ◽

Jean-Louis Gendrault ◽

Alain Venet ◽

...

Keyword(s):

Simian Immunodeficiency Virus ◽

Target Cells ◽

Virion Protein ◽

Immunodeficiency Virus ◽

Protein X

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Enhanced enzyme kinetics of reverse transcriptase variants cloned from animals infected with SIVmac239 lacking viral protein X

Journal of Biological Chemistry ◽

10.1074/jbc.ra120.015273 ◽

2020 ◽

Vol 295 (50) ◽

pp. 16975-16986

Author(s):

Si'Ana A. Coggins ◽

Dong-Hyun Kim ◽

Raymond F. Schinazi ◽

Ronald C. Desrosier ◽

Baek Kim

Keyword(s):

Steady State ◽

Viral Protein ◽

Catalytic Efficiency ◽

Myeloid Cell ◽

Immunodeficiency Virus ◽

Protein X ◽

Kinetics Of ◽

Hiv 1

HIV Type 1 (HIV-1) and simian immunodeficiency virus (SIV) display differential replication kinetics in macrophages. This is because high expression levels of the active host deoxynucleotide triphosphohydrolase sterile α motif domain and histidine-aspartate domain–containing protein 1 (SAMHD1) deplete intracellular dNTPs, which restrict HIV-1 reverse transcription, and result in a restrictive infection in this myeloid cell type. Some SIVs overcome SAMHD1 restriction using viral protein X (Vpx), a viral accessory protein that induces proteasomal degradation of SAMHD1, increasing cellular dNTP concentrations and enabling efficient proviral DNA synthesis. We previously reported that SAMHD1-noncounteracting lentiviruses may have evolved to harbor RT proteins that efficiently polymerize DNA, even at low dNTP concentrations, to circumvent SAMHD1 restriction. Here we investigated whether RTs from SIVmac239 virus lacking a Vpx protein evolve during in vivo infection to more efficiently synthesize DNA at the low dNTP concentrations found in macrophages. Sequence analysis of RTs cloned from Vpx (+) and Vpx (−) SIVmac239–infected animals revealed that Vpx (−) RTs contained more extensive mutations than Vpx (+) RTs. Although the amino acid substitutions were dispersed indiscriminately across the protein, steady-state and pre-steady-state analysis demonstrated that selected SIVmac239 Vpx (−) RTs are characterized by higher catalytic efficiency and incorporation efficiency values than RTs cloned from SIVmac239 Vpx (+) infections. Overall, this study supports the possibility that the loss of Vpx may generate in vivo SIVmac239 RT variants that can counteract the limited availability of dNTP substrate in macrophages.

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Inhibitory Effects of HIV-2 Vpx on Replication of HIV-1

Journal of Virology ◽

10.1128/jvi.00554-18 ◽

2018 ◽

Vol 92 (14) ◽

Cited By ~ 1

Author(s):

Mohamed Mahdi ◽

Zsófia Szojka ◽

János András Mótyán ◽

József Tőzsér

Keyword(s):

Cell Culture ◽

Human Immunodeficiency Virus ◽

Viral Protein ◽

Dual Infection ◽

Cellular Level ◽

Potential Candidate ◽

Accessory Gene ◽

Immunodeficiency Virus ◽

Protein X ◽

Hiv 1

ABSTRACTHuman immunodeficiency virus type 1 (HIV-1) and HIV-2 share a striking genomic resemblance; however, variability in the genetic sequence accounts for the presence of unique accessory genes, such as the viral protein X (vpx) gene in HIV-2. Dual infection with both viruses has long been described in the literature, yet the molecular mechanism of how dually infected patients tend to do better than those who are monoinfected with HIV-1 has not yet been explored. We hypothesized that in addition to extracellular mechanisms, an HIV-2 accessory gene is the culprit, and interference at the viral accessory/regulatory protein level is perhaps responsible for the attenuated pathogenicity of HIV-1 observed in dually infected patients. Following simulation of dual infection in cell culture experiments, we found that pretransduction of cells with HIV-2 significantly protects against HIV-1 transduction. Importantly, we have found that this dampening of the infectivity of HIV-1 was a result of interviral interference carried out by viral protein X of HIV-2, resulting in a severe hindrance to the replication dynamics of HIV-1, influencing both its early and late phases of the viral life cycle. Our findings shed light on potential intracellular interactions between the two viruses and broaden our understanding of the observed clinical spectrum in dually infected patients, highlighting HIV-2 Vpx as a potential candidate worth exploring in the fight against HIV-1.IMPORTANCEDual infection with human immunodeficiency virus types 1 and 2 is relatively common in areas of endemicity. For as-yet-unclarified reasons, patients who are dually infected were shown to have lower viral loads and generally a lower rate of progression to AIDS than those who are monoinfected. We aimed to explore dual infection in cell culture, to elucidate possible mechanisms by which HIV-2 may be able to exert such an effect. Our results indicate that on the cellular level, pretransduction of cells with HIV-2 significantly protects against HIV-1 transduction, which was found to be a result of interviral interference carried out by viral protein X of HIV-2. These findings broaden our knowledge of interviral interactions on the cellular level and may provide an explanation for the decreased pathogenicity of HIV-1 in dually infected patients, highlighting HIV-2 Vpx as a potential candidate worth exploring in the fight against HIV.

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