FIG 4.

Mutation of arginine (R) 424 to serine (S) confers resistance to binding of plasma antibodies. (A) Lysates of cells transfected with Bole1a_R424 and Bole1_S424 E1E2 expression constructs were used in enzyme-linked immunosorbent assays (ELISAs) to assess E1E2 binding by IgG in the same panel of 19 HCV-infected plasma samples. Each of the 19 plasma samples was assayed in duplicate, and antibody binding was detected using HRP-conjugated anti-human IgG secondary antibody. Each point represents the mean of two replicate values, and each line indicates binding by IgG from a unique plasma sample. P values were calculated using a paired two-tailed Student's t test. OD₄₅₀, optical density at 450 nm. (B) Lysates of E1E2-transfected cells used for ELISA measurements were analyzed by Western blotting in three dilutions to confirm that equal quantities of E1E2 were present. Blots were probed using anti-E2 antibody HC33.1.53 (25).