Figure 1

Anti-tetherin activities of Vpu proteins from major HIV-1 groups. (A) Origins of the four major groups of HIV-1. Solid arrows represent established transmissions, while broken arrows are more speculative events. (B) Ability of Vpu or Vpu-EGFP constructs to degrade CD4, examined by co-transfection of HeLa cells with a CD4 expression plasmid and the indicated Vpu plasmid. Western blots of cell lysates probed with the indicated antibodies are shown. The Vpu- constructs are described by both the HIV-1 group letter and the virus strain. As controls we included a group M Vpu from isolate NL4-3, and its S52/56N mutant that is unable to degrade CD4 [65]. (C) HIV-1 VLP release from tetherin-positive HeLa cells was measured by co-transfection of pHIV-1-pack (expresses HIV-1 Gag-Pol, Rev) in the absence (-) or presence of the indicated Vpu plasmids. VLP release was measured as the ratio of p24-reacting bands in the supernatants versus cell lysates following Western blot analysis, and made relative to the baseline level in the absence of Vpu, for n = 4 independent experiments. Statistical significance is indicated as p < 0.01 (**).