Resistance to Vpu antagonism requires mutations in the tyrosine and serine/threonine motifs in Tetherin.

<p>(A) Amino acid sequences of l-Tetherin mutants that disrupt the tyrosine motif (l-AxA), the serine/threonine residues (l-STS) and the combined mutant (l-SY). (B) 293T cells were transfected with HIV-1 Gag-Pol and Tetherin expression vectors plus increasing amounts of plasmids expressing the viral antagonist Vpu (25 or 100 ng). VLPs (Top panels) from supernatants were purified 48 h post transfection and analyzed for HIV-1 Gag p24 release by Western blot. Cell lysates were probed for cellular levels of HIV-1 Gag and Tetherin. As in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1002931#ppat-1002931-g002" target="_blank">Figure 2C</a> (*) indicates an unknown species often seen upon transient Tetherin expression in 293T cells. Titration of Vpu was detected using anti-Vpu antibody. GAPDH is used as a lysate loading control.