Viral relative infectivity and virion incorporation of mutant gp120. Gp120 incorporation data are shown as the percentage of the gp120/p24 ratio of the wt FE pseudovirus, with the wt gp120 incorporation set to 1.0. Relative infectivity was calculated by dividing the Log10 (RLU of mutant) by Log10 (RLU of wt). The data represent the means of three independent experiments, and the error bars indicate the standard deviations from the means. P values were calculated by using One-way analysis of variance (Tukey’s multiple comparison Test, SPSS 10.0). The difference of the mean infectivity and gp120 incorporation between wt and mutant is considered to be significant when a p value is <0.05, which is indicated with an asterisk in the figure.