Figure 4

Tetherin Counteraction by HIV-1 Group P Env. (A) FACS analysis of 293T cells cotransfected with a CD4 expression vector and pCAGGS plasmids expressing the indicated env alleles or an empty vector control. Shown are the cell surface expression levels of CD4 relative to those measured in cells transfected with the vector control. The mean (± SD) of two independent experiments is shown. (B) Infectivity of virions pseudotyped with HIV-1 P Env. TZM-bl reporter cells were infected with different dilutions of the supernatant of 293T cells cotransfected with a vpu-, nef- and env-deficient HIV-1 NL4-3 proviral construct and the indicated env alleles. Infection was performed in triplicates and results were confirmed in three additional experiments. (C) FACS analysis of 293T cells cotransfected with a human tetherin expression vector and pCAGGS plasmids expressing the indicated env alleles or an empty vector control. Shown are the cell surface expression levels of tetherin relative to those measured in cells transfected with the vector control. The mean (± SD) of two independent experiments is shown. (D) p24 release from 293T cells following transfection with a vpu-, env- and nef-defective proviral HIV-1 NL4-3 construct, pCAGGS plasmids expressing the indicated env alleles and different amounts of human tetherin expression plasmids. p24 release was quantified by ELISA. Values are shown as percentage of values obtained in the absence of tetherin. The mean of two independent experiments is shown.