FIG. 4.

Amino acid composition (amino acid positions 2195 to 2240) of NS5A protein of quasispecies from 13 patients. The alignment of amino acid sequences was deduced from the nucleotide sequences of 30 to 48 independent clones obtained before IFN-α treatment in 13 patients and 30 to 48 independent clones obtained 6 months after IFN-α withdrawal in 4 of them (patients 10 to 13). Relative frequencies of the variants are shown on the right, as determined by clonal frequency analysis by means of SSCP. Patients 1 to 5 were sustained virological responders to 3 MU of IFN-α three times a week for 6 months; i.e., they cleared HCV during treatment and were still nonviremic 6 months later. Patients 6 to 13 were nonresponders. The HCV-J sequence, reported in 1990 by Kato et al. (33), is given for comparison at the top, and the variants with a sequence identical to HCV-J are identified by an asterisk. The three serine residues mandatory for hyperphosphorylation of the product of the NS5A gene (68) are underlined. Amino acid positions 2217 to 2218, at which nonsynonymous mutations were frequently found, are identified by +.