Fig 3.

Pseudo-single cycle infectivity assays for each HIV-1 mutant in A3-null THP-1 cells. (A) Schematic of the susceptibility of HIV-1 Vif mutants to HIV-1 restriction activity by A3F and A3G proteins. Key amino acid residues of Vif that determine the susceptibility of HIV-1 IIIB to restriction by A3F and A3G proteins. −, resistance; +, sensitivity. (B) Representative infectivity of Vif-proficient, Vif-deficient, Vif4A, Vif5A, and Vif4A5A HIV-1 mutants produced from parental or A3-null THP-1 cells. Top panels show the infectivity of indicated HIV-1 mutants produced in parental or A3-null THP-1 cells. The amounts of produced viruses used to infect TZM-bl cells were normalized to p24 levels. Each bar represents the average of four independent experiments with SD. Data are presented as infectivity relative to Vif-proficient HIV-1 (WT). Statistical significance was assessed using the two-sided paired t test. *P < 0.05 compared to Vif-proficient HIV-1. Bottom panels are representative western blots of three independent experiments. Levels of indicated viral and cellular proteins in viral particles and whole-cell lysates are shown. p24 and HSP90 were used as loading controls.