Neither tetherin nor Vpu affect viral kinetics of initial cell-free infection. A. Shown are representative Western blots of material derived from wt and Δvpu viral particles stained for Env and CA p24 (top), as well as Env band intensity values, relative to CA p24, derived by quantification of the representative Western blot using ImageJ software (bottom). Supernatants from 293T transfections were ultracentrifuged and viral extracts analyzed by Western blot, normalized for CA p24. B & C Tetherinpos (B) and tetherinneg (C) Sup-T1 cells were infected with wt or Δvpu virus by spinoculation and cells were monitored for virus-derived GFP expression by flow cytometry. Data are derived from three independent experiments; error bars represent SEM.