Fig. 3

Effects of C-terminal p6* tetra-peptide mutations on virus processing and infectivity. a Schematic representations of HIV-1 Gag and Gag-Pol expression constructs. HIV-1 Gag protein domains and pol-encoded proteins are indicated as described in the Fig. 1 caption. Native C-terminal p6* residues are shown in boldface. Altered amino acid residues are underlined. b 293T cells were transfected with designated constructs. Culture supernatants and cells were collected 48–72 h post-transfection and subjected to Western immunoblotting. c Relative virus particle processing efficiency of HIV-1 mutants. Virus-associated Pr55gag and p24gag levels were quantified by scanning immunoblot band densities. Ratios of p24gag to p55gag were determined for each mutant and normalized to those of the wt in parallel experiments. Bars indicate standard deviations. *p < 0.05; **p < 0.01; ***p < 0.001. d Infectivity of HIV-1 mutants. 293T cells were co-transfected with one of the designated constructs plus a VSV-G expression vector. At 48 h post-transfection, supernatants were collected, filtered, and used to infect HeLa cells. Infection and selection of drug-resistant colonies was performed as described in Methods. Infectivity for each mutant was determined as the ratio of mutant titers to wt titers, normalized to Gag protein levels in parallel experiments. ***p < 0.001