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The Expression of Functional Vpx during Pathogenic SIVmac Infections of Rhesus Macaques Suppresses SAMHD1 in CD4+ Memory T Cells.

Shingai M, Welbourn S, Brenchley JM, Acharya P, Miyagi E, Plishka RJ, Buckler-White A, Kwong PD, Nishimura Y, Strebel K, Martin MA - PLoS Pathog. (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.

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.

No MeSH data available.


Related in: MedlinePlus

The replication of Vpx defective SIV mutants is attenuated in rhesus macaque mononuclear cells.ConA-activated rhesus PBMCs (A and B), rhesus MDM (C and D) and SupT1-R5 cells (E and F) were infected with WT and Vpx mutant SIV stocks produced in transfected 293T cells. The indicated cell cultures were infected with equivalent amounts of virus inocula, based on particle-associated 32P -RT activity (approximately 5 × 106 cpm) and progeny virion production was monitored by measuring the RT activity released into the culture medium. The results in panels A and B, are shown as mean +/—s.e.m (n = 4). The parametric unpaired t test was performed using PRISM software. The significant p values (* p<0.05, ** p<0.01) for WT versus the X-del and X-Q76A Vpx mutants refer to the single time points at peak virus production. A representative result from at least two experiments is shown in panels C and D.
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ppat.1004928.g002: The replication of Vpx defective SIV mutants is attenuated in rhesus macaque mononuclear cells.ConA-activated rhesus PBMCs (A and B), rhesus MDM (C and D) and SupT1-R5 cells (E and F) were infected with WT and Vpx mutant SIV stocks produced in transfected 293T cells. The indicated cell cultures were infected with equivalent amounts of virus inocula, based on particle-associated 32P -RT activity (approximately 5 × 106 cpm) and progeny virion production was monitored by measuring the RT activity released into the culture medium. The results in panels A and B, are shown as mean +/—s.e.m (n = 4). The parametric unpaired t test was performed using PRISM software. The significant p values (* p<0.05, ** p<0.01) for WT versus the X-del and X-Q76A Vpx mutants refer to the single time points at peak virus production. A representative result from at least two experiments is shown in panels C and D.

Mentions: Compared to the WT viruses, both types of SIVmac239 or SIVmac316 Vpx mutants generated reduced amounts of progeny virions during infections of cultured Concanavalin A (ConA) stimulated rhesus PBMC (Fig 2A and 2B). The defective replication phenotype of the Vpx mutants was more profound during infections of rhesus monocyte derived macrophage (MDM) infections (Fig 2C and 2D). In contrast to the robust replication of the WT macrophage tropic SIVmac316 in rhesus MDM, replication of both the SIVmac316 Vpx deletion mutant and the SIVmac316 Vpx point mutant was blocked in these cells. As expected, neither the WT nor the Vpx mutants of the T cell tropic SIVmac239 were able to infect rhesus MDM (Fig 2C). The SIVmac239 and SIVma316 X-Q76A Vpx point mutants both exhibited replication kinetics in human SupT1-R5 cells indistinguishable from corresponding WT viruses (Fig 2E and 2F), consistent with results reporting that SupT1-R5 cells do not express the SAMHD1 protein [8], and confirming the absence of any inherent replication defects in these mutant viruses.


The Expression of Functional Vpx during Pathogenic SIVmac Infections of Rhesus Macaques Suppresses SAMHD1 in CD4+ Memory T Cells.

Shingai M, Welbourn S, Brenchley JM, Acharya P, Miyagi E, Plishka RJ, Buckler-White A, Kwong PD, Nishimura Y, Strebel K, Martin MA - PLoS Pathog. (2015)

The replication of Vpx defective SIV mutants is attenuated in rhesus macaque mononuclear cells.ConA-activated rhesus PBMCs (A and B), rhesus MDM (C and D) and SupT1-R5 cells (E and F) were infected with WT and Vpx mutant SIV stocks produced in transfected 293T cells. The indicated cell cultures were infected with equivalent amounts of virus inocula, based on particle-associated 32P -RT activity (approximately 5 × 106 cpm) and progeny virion production was monitored by measuring the RT activity released into the culture medium. The results in panels A and B, are shown as mean +/—s.e.m (n = 4). The parametric unpaired t test was performed using PRISM software. The significant p values (* p<0.05, ** p<0.01) for WT versus the X-del and X-Q76A Vpx mutants refer to the single time points at peak virus production. A representative result from at least two experiments is shown in panels C and D.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4440783&req=5

ppat.1004928.g002: The replication of Vpx defective SIV mutants is attenuated in rhesus macaque mononuclear cells.ConA-activated rhesus PBMCs (A and B), rhesus MDM (C and D) and SupT1-R5 cells (E and F) were infected with WT and Vpx mutant SIV stocks produced in transfected 293T cells. The indicated cell cultures were infected with equivalent amounts of virus inocula, based on particle-associated 32P -RT activity (approximately 5 × 106 cpm) and progeny virion production was monitored by measuring the RT activity released into the culture medium. The results in panels A and B, are shown as mean +/—s.e.m (n = 4). The parametric unpaired t test was performed using PRISM software. The significant p values (* p<0.05, ** p<0.01) for WT versus the X-del and X-Q76A Vpx mutants refer to the single time points at peak virus production. A representative result from at least two experiments is shown in panels C and D.
Mentions: Compared to the WT viruses, both types of SIVmac239 or SIVmac316 Vpx mutants generated reduced amounts of progeny virions during infections of cultured Concanavalin A (ConA) stimulated rhesus PBMC (Fig 2A and 2B). The defective replication phenotype of the Vpx mutants was more profound during infections of rhesus monocyte derived macrophage (MDM) infections (Fig 2C and 2D). In contrast to the robust replication of the WT macrophage tropic SIVmac316 in rhesus MDM, replication of both the SIVmac316 Vpx deletion mutant and the SIVmac316 Vpx point mutant was blocked in these cells. As expected, neither the WT nor the Vpx mutants of the T cell tropic SIVmac239 were able to infect rhesus MDM (Fig 2C). The SIVmac239 and SIVma316 X-Q76A Vpx point mutants both exhibited replication kinetics in human SupT1-R5 cells indistinguishable from corresponding WT viruses (Fig 2E and 2F), consistent with results reporting that SupT1-R5 cells do not express the SAMHD1 protein [8], and confirming the absence of any inherent replication defects in these mutant viruses.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.

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.

No MeSH data available.


Related in: MedlinePlus