FIG 6.
Protection from HIV-1 superinfection. (A) Representative flow cytometry plots from the HIV-1 infection susceptibility assay. TZM cells transfected with GFP alone were subsequently exposed to HIV-ENVJRFL, HIV-ENVNL43, or VSVg-pseudotyped HIV-1 in the presence of anti-CD4 MAb, MVC, or AMD3100 (plus untreated control). Susceptibility of TZM cells transfected with NefSF2-GFP to various HIV-1 strains is also shown. The live (negative for 7-AAD) GFP+ subset was gated and then analyzed for intracellular expression of p24 Gag protein. The proportion of p24 Gag+ cells within the live GFP+ subset is indicated. (B) Receptor downregulation functions of NefSF2 and site-directed mutants AxxA and EDAA (left). Relative protection conferred by NefSF2, AxxA, and EDAA mutants from infection by HIV-ENVJRFL or HIV-ENVNL43 (right). (C) TZM-bl cells transfected with various EC-derived Nef clones and their chimeras were subsequently exposed to HIV-ENVJRFL (left) and ENVNL43 (right). Protection from HIV-1 infection was normalized to that with NefSF2, which was arbitrarily set at 100%, and each data point reflects the mean ± SD of triplicate determinations.