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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

Alignment of Vpx amino acid sequences amplified from the plasma of monkeys inoculated with SIV Vpx X-Q76A mutants.SGA plus sequencing was used to generate vpx gene sequences present in the plasma of (A) SIVmac239 X-Q76A infected animals (K42, K2M, JWR, and JHL) and (B) SIVmac316 X-Q76A infected animals (JA4X, DX39, JLP, and K31) at week 35 PI. The sequence of WT SIVmac Vpx is shown at the top and the animal identifications are indicated on the left. Amino acids highlighted in red represent changes conferring putative revertant phenotypic changes. Amino acid substitutions in black are not thought to contribute to revertant phenotype because when present alone and in the absence of a change in the starting Q76A Vpx mutation (e.g. in the K2M virus), they fail to restore WT properties. The nucleotide changes corresponding to the putative revertant amino acid substitutions at Vpx residue 76 or residue 32 are shown at the bottom of each panel.
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ppat.1004928.g006: Alignment of Vpx amino acid sequences amplified from the plasma of monkeys inoculated with SIV Vpx X-Q76A mutants.SGA plus sequencing was used to generate vpx gene sequences present in the plasma of (A) SIVmac239 X-Q76A infected animals (K42, K2M, JWR, and JHL) and (B) SIVmac316 X-Q76A infected animals (JA4X, DX39, JLP, and K31) at week 35 PI. The sequence of WT SIVmac Vpx is shown at the top and the animal identifications are indicated on the left. Amino acids highlighted in red represent changes conferring putative revertant phenotypic changes. Amino acid substitutions in black are not thought to contribute to revertant phenotype because when present alone and in the absence of a change in the starting Q76A Vpx mutation (e.g. in the K2M virus), they fail to restore WT properties. The nucleotide changes corresponding to the putative revertant amino acid substitutions at Vpx residue 76 or residue 32 are shown at the bottom of each panel.

Mentions: Rhesus macaques were inoculated intrarectally with 1 x 104 TCID50 of SIVmac239 WT or SIVmac239 X-Q76A derivatives (A and C) or 1 x 103 TCID50 of SIVmac316 WT or the SIVmac316X-Q76A derivatives (B and D). The infectious virus titers in the inocula were determined by end-point dilution using SAMHD1 negative SupT1-R5 cells to avoid suppressive effects of SAMHD1 restriction. Plasma viral copies/ml are shown in panel A and C. Memory CD4+ T cell counts/μl are shown in panel C and D. Black curves: WT virus; blue curves: putative revertant Vpx mutants; red curves: non-revertant Vpx mutants. (E) Amino acid substitutions present in the starting Q76A Vpx mutant virus or in the putative revertant virus populations present in the plasmas of macaques K42 and JAX4 at week 35 PI, based on SGA (see Fig 6) are shown. The locations of the three helical domains of SIVmac Vpx are indicated.


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)

Alignment of Vpx amino acid sequences amplified from the plasma of monkeys inoculated with SIV Vpx X-Q76A mutants.SGA plus sequencing was used to generate vpx gene sequences present in the plasma of (A) SIVmac239 X-Q76A infected animals (K42, K2M, JWR, and JHL) and (B) SIVmac316 X-Q76A infected animals (JA4X, DX39, JLP, and K31) at week 35 PI. The sequence of WT SIVmac Vpx is shown at the top and the animal identifications are indicated on the left. Amino acids highlighted in red represent changes conferring putative revertant phenotypic changes. Amino acid substitutions in black are not thought to contribute to revertant phenotype because when present alone and in the absence of a change in the starting Q76A Vpx mutation (e.g. in the K2M virus), they fail to restore WT properties. The nucleotide changes corresponding to the putative revertant amino acid substitutions at Vpx residue 76 or residue 32 are shown at the bottom of each panel.
© Copyright Policy
Related In: Results  -  Collection

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

ppat.1004928.g006: Alignment of Vpx amino acid sequences amplified from the plasma of monkeys inoculated with SIV Vpx X-Q76A mutants.SGA plus sequencing was used to generate vpx gene sequences present in the plasma of (A) SIVmac239 X-Q76A infected animals (K42, K2M, JWR, and JHL) and (B) SIVmac316 X-Q76A infected animals (JA4X, DX39, JLP, and K31) at week 35 PI. The sequence of WT SIVmac Vpx is shown at the top and the animal identifications are indicated on the left. Amino acids highlighted in red represent changes conferring putative revertant phenotypic changes. Amino acid substitutions in black are not thought to contribute to revertant phenotype because when present alone and in the absence of a change in the starting Q76A Vpx mutation (e.g. in the K2M virus), they fail to restore WT properties. The nucleotide changes corresponding to the putative revertant amino acid substitutions at Vpx residue 76 or residue 32 are shown at the bottom of each panel.
Mentions: Rhesus macaques were inoculated intrarectally with 1 x 104 TCID50 of SIVmac239 WT or SIVmac239 X-Q76A derivatives (A and C) or 1 x 103 TCID50 of SIVmac316 WT or the SIVmac316X-Q76A derivatives (B and D). The infectious virus titers in the inocula were determined by end-point dilution using SAMHD1 negative SupT1-R5 cells to avoid suppressive effects of SAMHD1 restriction. Plasma viral copies/ml are shown in panel A and C. Memory CD4+ T cell counts/μl are shown in panel C and D. Black curves: WT virus; blue curves: putative revertant Vpx mutants; red curves: non-revertant Vpx mutants. (E) Amino acid substitutions present in the starting Q76A Vpx mutant virus or in the putative revertant virus populations present in the plasmas of macaques K42 and JAX4 at week 35 PI, based on SGA (see Fig 6) are shown. The locations of the three helical domains of SIVmac Vpx are indicated.

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