FIG. 4.

Mutations that alter HIV-1 core stability modulate HIV-1 sensitivity to PF74. (A) Wild-type and mutant HIV-1 viruses were titrated on HeLa-P4 cells in the presence of various concentrations of PF74. For each virus, infection at each concentration of PF74 was calculated as a percentage of the corresponding untreated virus infection. The experiment was performed more than three times, with similar results. (B) Binding of ³H-PF74 to the indicated HIV-1 mutant particles was tested. Samples of concentrated virus particles were incubated with the radiolabeled compound, pelleted, resuspended in PBS, and then repelleted through a 20% sucrose cushion. The pelleted particles were dissolved in sodium dodecyl sulfate-containing sample buffer, and the levels of ³H and CA protein were quantified by liquid scintillation counting and ELISA, respectively. The ratios of the radioactive signals to the CA protein were calculated and expressed as a percentage of the wild-type value. Shown are the mean values obtained from averaging the data from at least six independent experiments, with error bars representing one standard deviation.