HIV-1 Vpu- and Nef-deletion mutants lose their capacity to inhibit CD1d expression and NKT-cell activation. (A) Human monocyte-derived DCs were infected with VSV-G pseudotyped HIV-1 81Awt or mutants lacking the expression of Vpu (ΔVpu), Nef (ΔNef), or both (ΔNefΔVpu), and CD1d down-regulation was analyzed at day 4 after infection. CD1d down-regulation by 81Awt was set as 100%. Data show experiments with DCs generated from 8 different donors. Error bars represent mean ± SE; **P < .01; ***P < .001. (B) NKT cells were coincubated with αGalCer-loaded DCs infected with the viruses indicated for 2 hours in the presence of brefeldin A and subsequently analyzed for expression of p24 (green) and IFN-γ production (red). The data are representative of 3 independent experiments. Scale bars, 15 μm.