Figure 3

Enhancement of virus release in the presence of human tetherin by chimeras between HIV-1 and SIVcpz/gor Vpu. (A) Infectious virus yield from 293T cells co-transfected with an HIV-1 NL4-3 Δvpu construct and vectors expressing the indicated vpu alleles in combination with various quantities of plasmids expressing tetherin. Shown are average values derived from triplicate infections of TZM-bl indicator cells relative to those obtained in the absence of tetherin (100%). The mean of three independent experiments is shown. The results were verified by measuring the cell-free p24 levels by ELISA. (B) Infectious virus yield from 293T cells co-transfected with the proviral HIV-1 NL4-3 Δvpu construct (4 μg), pCGCG vectors expressing the indicated vpu alleles (1 ng) and a plasmid expressing human tetherin (50 ng). Shown are average values (±SEM) derived from three independent experiments each involving triplicate infections of TZM-bl indicator cells. (C, D) Detection of (C) infectious HIV-1 and (D) p24 antigen in the supernatant of HeLa cells that express tetherin endogenously and were co-transfected with HIV-1 NL4-3 Δvpu and the indicated Vpu expression constructs. Data represent average values (±SEM) derived from three experiments. (E-G) Correlation between infectious virus release from HeLa cells and (E) p24 release, (F) infectious virus release from 293T cells and (G) tetherin cell surface expression levels of HeLa cells. (H) Correlation of infectious virus release and tetherin surface expression levels of 293T cells.