Vpu down-modulates induced tetherin cell surface expression of tetherinpos Sup-T1 cells. A. Western blot for Vpu (bottom) and CA p24 (top) of wt- and Δvpu-infected cells. B. Tetherin expression levels upon induction over the course of 72 h. Tetherin cell surface expression was induced by 100 ng/ml doxycycline and was detected by flow cytometry using a PerCP-labeled secondary antibody directed against a primary anti-tetherin antibody. Data points are derived from three independent experiments. C. Histogram plot of representative tetherin cell surface expression of non-induced (no dox./black) and induced (100 ng/ml) Sup-T1 cells (green), and induced cells infected with wt (blue) and Δvpu (red) BR-NL43-IRES-eGFP viral clones, as well as control cells stained only with PerCP-labeled secondary antibody (Ab control/grey). Cells were gated for infections via GFP expression as a marker for viral gene expression, 48 h post infection. D. Geometric means ± standard error of the mean (SEM) of tetherin cell surface expression in uninfected cells and cells infected with wt and Δvpu BR-NL43-IRES-eGFP viral clone. Data are derived from three independent experiments; error bars represent SEM.