FIG 4.
Effects of SC29EK-induced mutations on the functionality of HIV-1 Env. (A) Relative infectivity of HIV-1NL4-3 and its mutants determined by a single-cycle infection assay. The wild-type (WT) and mutant pseudoviruses were normalized to a fixed amount by p24 antigen, and viral entry was tested in TZM-bl cells. The luciferase activity was measured and corrected for background, the luciferase activity of wild-type HIV-1NL4-3 was treated as 100%, and the relative activities of other mutant viruses were calculated accordingly. A t test was performed to judge the significance of the difference between the WT and mutants. * and **, P < 0.01 and P < 0.05, respectively. (B) Kinetics of HIV-1 Env-mediated cell-cell fusion determined by a dual split-protein assay (DSP). For both viral entry and fusion, data were derived from the results of three independent experiments and are expressed as means and standard deviations.