(A) Degradation of SAMHD1 by Vpx in PBMCs by HIV-2. Flow cytometry histograms showing intracellular staining of SAMHD1 in lymphocytes infected with wild-type HIV-2 (left) or HIV-2 defective for Vpx protein (right). Three days after infection, cells were fixed, permeabilized, and stained using a primary-specific SAMHD1 antibody followed by an APC-conjugated secondary antibody. The secondary antibody alone was used as a control (shaded histogram). Representative histograms of one experiment are shown. The experiment was performed in three independent donors. (B) AZT antiviral potency is decreased in HIV-2-infected PBMCs in vitro. CD3/CD8-activated PBMCs from donors (n = 12) were infected with wild-type GFP-expressing HIV-2 or HIV-2 defective for Vpx protein. Antiviral activity of AZT (1 μg/ml) was assessed. (C) AZT antiviral potency is decreased in HIV-1-infected PBMCs in vitro. CD3/CD8-activated PBMCs from the same donors as in panel B (n = 12) were infected with NL4-3*GFP carrying or not Vpx protein. Antiviral activity of AZT (1 mg/ml) was assessed. ND, no drug. ***, P < 0.0005.