Residue 6-8 mutations result in varying levels of resistance to BVM. (A) Virus stocks produced from HeLa cells either in the absence of BVM or in the presence of 1 μg/ml BVM were used to infect the TZM-bl indicator cell line. Infectivity was measured 48 h postinfection by determining levels of luciferase activity. Relative infectivity was calculated by normalization of the untreated WT virus at the 12.5 μl viral input to 100%. Paired t tests were performed to evaluate differences between means. Statistically significant differences between pairs of means are indicated (*** P = 0.0001, ** P = 0.001, * = 0.01). (B) Virus inputs were verified by confirming that virus stocks contained comparable RT activities. All data shown are means and standard deviations from three independent experiments, performed in duplicate.