Limits...
HIV-2 infects resting CD4+ T cells but not monocyte-derived dendritic cells.

Chauveau L, Puigdomenech I, Ayinde D, Roesch F, Porrot F, Bruni D, Visseaux B, Descamps D, Schwartz O - Retrovirology (2015)

Bottom Line: HIV-2 particles did not potently fuse with MDDCs and did not lead to efficient viral DNA synthesis, even in the presence of Vpx.In these cells, an entry defect prevents viral fusion and reverse transcription independently of SAMHD1.We propose that HIV-2, like HIV-1, does not productively infect MDDCs, possibly to avoid triggering an immune response mediated by these cells.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Human Immunodeficiency Virus-type 2 (HIV-2) encodes Vpx that degrades SAMHD1, a cellular restriction factor active in non-dividing cells. HIV-2 replicates in lymphocytes but the susceptibility of monocyte-derived dendritic cells (MDDCs) to in vitro infection remains partly characterized.

Results: Here, we investigated HIV-2 replication in primary CD4+ T lymphocytes, both activated and non-activated, as well as in MDDCs. We focused on the requirement of Vpx for productive HIV-2 infection, using the reference HIV-2 ROD strain, the proviral clone GL-AN, as well as two primary HIV-2 isolates. All HIV-2 strains tested replicated in activated CD4+ T cells. Unstimulated CD4+ T cells were not productively infected by HIV-2, but viral replication was triggered upon lymphocyte activation in a Vpx-dependent manner. In contrast, MDDCs were poorly infected when exposed to HIV-2. HIV-2 particles did not potently fuse with MDDCs and did not lead to efficient viral DNA synthesis, even in the presence of Vpx. Moreover, the HIV-2 strains tested were not efficiently sensed by MDDCs, as evidenced by a lack of MxA induction upon viral exposure. Virion pseudotyping with VSV-G rescued fusion, productive infection and HIV-2 sensing by MDDCs.

Conclusion: Vpx allows the non-productive infection of resting CD4+ T cells, but does not confer HIV-2 with the ability to efficiently infect MDDCs. In these cells, an entry defect prevents viral fusion and reverse transcription independently of SAMHD1. We propose that HIV-2, like HIV-1, does not productively infect MDDCs, possibly to avoid triggering an immune response mediated by these cells.

Show MeSH

Related in: MedlinePlus

Vpx is necessary for HIV-2 infection in unstimulated CD4+ T cells. (a) Replication of HIV-2 GL-AN, expressing or not Vpx, in activated CD4+ T cells. Primary activated CD4+ T cells were infected with HIV-2 GL-AN WT and GL-AN ∆Vpx (20–30 ng p27 mL−1). Viral replication was followed as in Figure 1a. Upper panels: Mean ± SD of 6 independent donors. Lower panels: Gag and SAMHD1 expression at day 7 p.i., in one representative donor. ns: non significant (b) Role of Vpx in HIV-2 infection of resting, unstimulated CD4+ T cells. Unstimulated CD4+ T cells were exposed to HIV-2 GL-AN WT and GL-AN ∆Vpx (30 and 90 ng p27 mL−1, respectively) as described in Figure 1c. One day post-infection, the cells were activated with PHA/IL-2. Gag and SAMHD1 levels are shown at different days p.i. Data are Mean ± SEM of 3 independent donors. *: p-value < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4307230&req=5

Fig2: Vpx is necessary for HIV-2 infection in unstimulated CD4+ T cells. (a) Replication of HIV-2 GL-AN, expressing or not Vpx, in activated CD4+ T cells. Primary activated CD4+ T cells were infected with HIV-2 GL-AN WT and GL-AN ∆Vpx (20–30 ng p27 mL−1). Viral replication was followed as in Figure 1a. Upper panels: Mean ± SD of 6 independent donors. Lower panels: Gag and SAMHD1 expression at day 7 p.i., in one representative donor. ns: non significant (b) Role of Vpx in HIV-2 infection of resting, unstimulated CD4+ T cells. Unstimulated CD4+ T cells were exposed to HIV-2 GL-AN WT and GL-AN ∆Vpx (30 and 90 ng p27 mL−1, respectively) as described in Figure 1c. One day post-infection, the cells were activated with PHA/IL-2. Gag and SAMHD1 levels are shown at different days p.i. Data are Mean ± SEM of 3 independent donors. *: p-value < 0.05.

Mentions: To assess the role of Vpx in infection of activated or unstimulated CD4+ T cells, we followed replication of an HIV-2 molecular clone, the GL-AN provirus, expressing or not the viral accessory protein (GL-AN WT and ∆Vpx, respectively) [50]. GL-AN is a chimerical strain, originating from a virus isolated in a Ghanaian patient, and containing a large part of the HIV-2 ROD env sequence [50]. GL-AN replicated in activated primary CD4+ T cells, and the absence of Vpx was associated with a slight but non-significant decrease of viral growth (Figure 2a). GL-AN WT, and not ∆Vpx down-regulated SAMHD1 in infected cells (Figure 2a). With GL-AN WT, the extent of SAMHD1 down-regulation was less marked than with ROD, ROK and TOE (Figure 1b). This suggests that, as previously reported [41], Vpx from different viral isolates down-regulate SAMHD1 with various efficiencies. However, with GL-AN WT, the majority of Gag + cells were SAMHD1-negative, whereas ∆Vpx replicated in SAMHD1-positive cells (Figure 2a). This is not surprising since SAMHD1 is phosphorylated in cycling cells, and this phosphorylation inactivates the enzyme [38-40].Figure 2


HIV-2 infects resting CD4+ T cells but not monocyte-derived dendritic cells.

Chauveau L, Puigdomenech I, Ayinde D, Roesch F, Porrot F, Bruni D, Visseaux B, Descamps D, Schwartz O - Retrovirology (2015)

Vpx is necessary for HIV-2 infection in unstimulated CD4+ T cells. (a) Replication of HIV-2 GL-AN, expressing or not Vpx, in activated CD4+ T cells. Primary activated CD4+ T cells were infected with HIV-2 GL-AN WT and GL-AN ∆Vpx (20–30 ng p27 mL−1). Viral replication was followed as in Figure 1a. Upper panels: Mean ± SD of 6 independent donors. Lower panels: Gag and SAMHD1 expression at day 7 p.i., in one representative donor. ns: non significant (b) Role of Vpx in HIV-2 infection of resting, unstimulated CD4+ T cells. Unstimulated CD4+ T cells were exposed to HIV-2 GL-AN WT and GL-AN ∆Vpx (30 and 90 ng p27 mL−1, respectively) as described in Figure 1c. One day post-infection, the cells were activated with PHA/IL-2. Gag and SAMHD1 levels are shown at different days p.i. Data are Mean ± SEM of 3 independent donors. *: p-value < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4307230&req=5

Fig2: Vpx is necessary for HIV-2 infection in unstimulated CD4+ T cells. (a) Replication of HIV-2 GL-AN, expressing or not Vpx, in activated CD4+ T cells. Primary activated CD4+ T cells were infected with HIV-2 GL-AN WT and GL-AN ∆Vpx (20–30 ng p27 mL−1). Viral replication was followed as in Figure 1a. Upper panels: Mean ± SD of 6 independent donors. Lower panels: Gag and SAMHD1 expression at day 7 p.i., in one representative donor. ns: non significant (b) Role of Vpx in HIV-2 infection of resting, unstimulated CD4+ T cells. Unstimulated CD4+ T cells were exposed to HIV-2 GL-AN WT and GL-AN ∆Vpx (30 and 90 ng p27 mL−1, respectively) as described in Figure 1c. One day post-infection, the cells were activated with PHA/IL-2. Gag and SAMHD1 levels are shown at different days p.i. Data are Mean ± SEM of 3 independent donors. *: p-value < 0.05.
Mentions: To assess the role of Vpx in infection of activated or unstimulated CD4+ T cells, we followed replication of an HIV-2 molecular clone, the GL-AN provirus, expressing or not the viral accessory protein (GL-AN WT and ∆Vpx, respectively) [50]. GL-AN is a chimerical strain, originating from a virus isolated in a Ghanaian patient, and containing a large part of the HIV-2 ROD env sequence [50]. GL-AN replicated in activated primary CD4+ T cells, and the absence of Vpx was associated with a slight but non-significant decrease of viral growth (Figure 2a). GL-AN WT, and not ∆Vpx down-regulated SAMHD1 in infected cells (Figure 2a). With GL-AN WT, the extent of SAMHD1 down-regulation was less marked than with ROD, ROK and TOE (Figure 1b). This suggests that, as previously reported [41], Vpx from different viral isolates down-regulate SAMHD1 with various efficiencies. However, with GL-AN WT, the majority of Gag + cells were SAMHD1-negative, whereas ∆Vpx replicated in SAMHD1-positive cells (Figure 2a). This is not surprising since SAMHD1 is phosphorylated in cycling cells, and this phosphorylation inactivates the enzyme [38-40].Figure 2

Bottom Line: HIV-2 particles did not potently fuse with MDDCs and did not lead to efficient viral DNA synthesis, even in the presence of Vpx.In these cells, an entry defect prevents viral fusion and reverse transcription independently of SAMHD1.We propose that HIV-2, like HIV-1, does not productively infect MDDCs, possibly to avoid triggering an immune response mediated by these cells.

View Article: PubMed Central - PubMed

ABSTRACT

Background: Human Immunodeficiency Virus-type 2 (HIV-2) encodes Vpx that degrades SAMHD1, a cellular restriction factor active in non-dividing cells. HIV-2 replicates in lymphocytes but the susceptibility of monocyte-derived dendritic cells (MDDCs) to in vitro infection remains partly characterized.

Results: Here, we investigated HIV-2 replication in primary CD4+ T lymphocytes, both activated and non-activated, as well as in MDDCs. We focused on the requirement of Vpx for productive HIV-2 infection, using the reference HIV-2 ROD strain, the proviral clone GL-AN, as well as two primary HIV-2 isolates. All HIV-2 strains tested replicated in activated CD4+ T cells. Unstimulated CD4+ T cells were not productively infected by HIV-2, but viral replication was triggered upon lymphocyte activation in a Vpx-dependent manner. In contrast, MDDCs were poorly infected when exposed to HIV-2. HIV-2 particles did not potently fuse with MDDCs and did not lead to efficient viral DNA synthesis, even in the presence of Vpx. Moreover, the HIV-2 strains tested were not efficiently sensed by MDDCs, as evidenced by a lack of MxA induction upon viral exposure. Virion pseudotyping with VSV-G rescued fusion, productive infection and HIV-2 sensing by MDDCs.

Conclusion: Vpx allows the non-productive infection of resting CD4+ T cells, but does not confer HIV-2 with the ability to efficiently infect MDDCs. In these cells, an entry defect prevents viral fusion and reverse transcription independently of SAMHD1. We propose that HIV-2, like HIV-1, does not productively infect MDDCs, possibly to avoid triggering an immune response mediated by these cells.

Show MeSH
Related in: MedlinePlus