FIG. 1.
Effects of changes in V4 of HIV-1YU2 gp120 on entry and neutralization. A. The amino acid sequence of the wt HIV-1YU2 gp120 glycoprotein V4 region and flanking sequences. The changes associated with the N407K, Insert, and Insert-N407K mutants are underlined. B. 293T cells expressing the indicated HIV-1YU2 envelope glycoproteins were radiolabeled and lysed. Cell lysates and supernatants were precipitated with 3-μl portions of pooled sera from HIV-1-infected individuals. C. The abilities of the wt and mutant envelope glycoproteins to complement infection by an env-defective, recombinant HIV-1 expressing luciferase is shown. Control viruses with no envelope glycoproteins (Mock) were tested in parallel. Recombinant viruses were incubated with Cf2Th-CD4/CCR5 cells, and 2 days later, luciferase activity in the cells was determined. The mean values ± ranges of variation (error bars) from three parallel infections are shown. D. Recombinant, luciferase-expressing viruses with the indicated envelope glycoproteins were incubated with different concentrations (in micrograms per milliliter) of either the IgG1b12 or 2F5 antibody. Virus-antibody mixtures were added to Cf2Th-CD4/CCR5 target cells, and 2 days later, luciferase in the target cells was assessed. The mean values ± ranges of variation (error bars) from three parallel experiments are shown.