FIG 6.

Effect of E1 mutations on E1E2 interaction with HCV neutralizing antibodies and CD81. CD81 inhibition assays (A) and AR5A (B) and AR4A (C) neutralization experiments were carried out by incubating E1 mutants or wild-type virus with increasing concentrations of human CD81-LEL, MAb AR5A, or MAb AR4A at 37°C for 2 h. The mixture was then added to naive Huh-7 cells that were plated 1 day before. At 72 h postinfection, infectivity was determined by immunofluorescence. The values are the combined data from three independent experiments. The error bars represent standard errors of the means. Results were compared to those of the wild type and a P value of <0.05 was obtained for mutants M323A, W326A, P328A, and R339A in the AR5A and AR4A neutralization experiments. (D) Recognition of HCV E1 and E2 glycoproteins by conformation-sensitive anti-E1E2 MAb AR4A. At 48 h postelectroporation, E1 and E2 proteins from cell lysates were analyzed by immunoprecipitation with MAb AR4A. Immunoprecipitated proteins were revealed by Western blotting with MAbs A4 and 3/11.