Fig. 1.

M group Vpu has evolved to antagonize tetherin through its TM and TM proximal domains. (a) Alignment of NL4-3 M group and Ca9 and BCF06 O group Vpus, as well as schematics of the Vpu chimeras. (b) Titres of HIV-1 released from 293T cells cotransfected with a titration of NL4-3, Ca9 or BCF06 Vpu encoding plasmids, HIV-1 vectors and 100 ng human tetherin. (c, d, e, f and g) Titres of HIV-1 released from 293T cells cotransfected with 500 ng [(g) 200, 500, 700 and 1000 ng] of various Vpu encoding plasmids, HIV-1 vectors and 100 ng human tetherin. P24 staining of Western blots of viral supernatants and cell lysates reflect viral titres and indicate equal Gag expression. Vpu expression was measured by detecting the C-terminal HA-tag and β-actin was measured for loading control. Results are representative of three separate experiments.