FIG. 4.

Comparison of p24 and viral RNA levels as markers for the antiviral activities of drugs acting at different stages of HIV-1 replication. Infection of PM1 cells with NL4-3 and drug treatments were carried out as described in the legend to Fig. 1. For each of four different stages of viral replication, two or more drugs were individually added during ongoing replication at 5 days after infection (all drugs listed in Table 1 were used individually). Measurements of p24 (by ELISA) or viral RNA (by qRT-PCR) levels were performed with samples collected 6 days after infection (1 day after drug addition). Each bar represents the mean inhibition of virus production relative to that for the no-drug controls for all drugs acting at a particular stage of replication (Table 1); average values for each drug were calculated from the means of three independent experiments, each of which was performed in replicate wells. Error bars represent standard errors of the means. Unpaired two-tailed t tests were used to test for statistically significant differences between measurements of p24 or viral RNA as an indicator of inhibition of virus replication for each class of drug. n.s., not significant; ***, P < 0.0001.