FIG 4.
Gain of antitetherin activity may come at the cost of HLA-C downmodulation. (A) Alignment of the N termini of SIVcpz EK505 Vpu, HIV-1 N YBF30 Vpu, as well as several mutants mimicking adaptive changes upon cross-species transmission of SIVcpz to humans that ultimately resulted in the emergence of antitetherin activity (33, 46). (B) Purified CD4+ T cells were infected with SIVcpz EK505 carrying the indicated mutations in Vpu. At 3 days postinfection, surface levels of tetherin (top) and HLA-C (bottom) were determined by flow cytometry. (Left) Mean values from 3 to 11 independent experiments ± SEM. (Right) Representative primary data. Asterisks indicate statistically significant differences compared to the wild type (**, P < 0.01; ***, P < 0.001).