Figure 8

Ability of Vpu proteins to remove human tetherin from surface of cells. (A) HeLa cells were transfected with a control EGFP expression plasmid, HIV-1 Vpu or Vpu-EGFP fusion proteins from SIVmus/mon/gsn isolates. Non-permeabilized cells were incubated with anti-BST-2 antibody to reveal cell surface tetherin, followed by fixation and permeablization to visualize intracellular proteins. HIV-1 Vpu (untagged) was used as a positive control for tetherin removal from surface and visualized with an anti-Vpu antiserum, while the SIV Vpu-EGFP proteins and EGFP control were visualized using anti-GFP antibody. Both HIV-1 and SIVgsn Vpu proteins removed human tetherin from the cell surface, but SIVmus and SIVmon did not. Vpu-expressing cells are arrowed. (B) HeLa cells were transfected with a control EGFP expression plasmid alone or together with HIV-1 Vpu, or with each of the SIVmus/mon/gsn Vpu-EGFP expression plasmids. Cells were stained with anti-BST-2 antibody and analyzed by FACS. The histograms show cells gated for EGFP expression, with the control EGFP expression vector cells in black, and Vpu samples in blue.