Mutational analysis of PQVPLR, P
, and F
for Nef-mediated enhancement of virion infectivity. (A), HeLa-MAGI cells were infected with HIV-1SF2 and HIV-1SF2 with mutant nefs from Figures 1 and 2. ∆Xho represents HIV-1SF2 with its nef rendered non-functional by filling in the unique XhoI site with Klenow to make a four base insertion. β-galactosidase positive cells were counted 36 hours post-infection. Viral infectivity (blue cells per ng p24gag normalized to HIV-1SF2) is presented as the mean ± S.E.M. with n = 6. SF2Nef was set at 100%. An asterisk indicates a significantly lower value compared to SF2Nef by t test (p < 0.05). Also note that values for all mutated proteins were significantly higher than ∆Xho. (B), Lysates from the 293T producer cells for viruses presented in (A) were analyzed for Nef and p24gag (p24) expression by Western blot. Equal amounts of lysate protein were added to each lane.