Multiple elements in the Vpu CTD are required to fully antagonize Tetherin.

<p>(<b>A</b>) 293T cells were cotransfected with HIV-1 proviral (pNL4-3) plasmids expressing various mutant Vpu proteins, and with increasing amounts of a plasmid encoding WT Tetherin-HA. Infectious virion yield was measured using TZM indicator cells and is given in relative light units (RLU). (<b>B</b>) Western blot analysis of cell lysates and released particles from samples in panel (<b>A</b>) that were cotransfected with 0, 25, or 100 ng of Tetherin-HA. Blots of cell lysates were probed with α-HA and capsid α-CA antibodies. Blots of virion lysates were probed with α-CA antibodies. (<b>C</b>) Western blot analysis of Vpu expression from samples in panel (<b>A</b>) that were transfected with 100 ng of Tetherin. Blots were probed with an α-Vpu antibody.