Fig 1.

(A) Silver staining showing that p24 ELISA measures equal amounts of Gag products from the wild-type and protease mutant virion. An SDS-polyacrylamide gel was loaded with equal masses of p24, as determined by antigen-capture ELISA. The band signals were compared for the parental NL4-3 virus (lanes 1 to 3) and the poorly infectious G48V mutant (lanes 4 to 6). Threefold dilutions of each mutant were shown (lanes 1 and 4, 150 ng of p24; lanes 2 and 5, 50 ng of p24; lanes 3 and 6, 17 ng of p24). (B) Correlation analysis between SpIn values measured using the p24 ELISA and SpIn values measured using real-time RT PCR. The r² value was obtained from the statistical analysis using nonparametric (Spearman) correlation.