Nucleotide and amino acid diversities of E2/NS1 hypervariable region 1 and response to interferon therapy in patients with chronic hepatitis C virus infection

To clarify the relationship between nucleotide and amino acid diversities of the E2/NS1 hypervariable region 1 (HVR1) of hepatitis C virus (HCV) and response to subsequent interferon-α (IFN) therapy, pretreatment serum samples were studied from 13 Japanese patients, who were infected with HCV genotype 1b, had similar histological profiles and serum HCV RNA levels (1-10 million eq ml^-1), and were subsequently treated with the same IFN treatment protocol. Nucleotide sequence of HVR1 was determined by dideoxynucleotide chain termination in eight clones derived from each serum sample. Nucleotide and amino acid diversities were calculated from the mean of the genetic distances among these eight clones by six-parameter method. Of the 13 patients, four showed a complete and sustained response, three were complete responders followed by early relapse, and six were non-responders to IFN therapy. No significant differences in clinical or virological parameters among the three groups were found. There was no significant difference in the diversity of HVR1 among the three groups, indicating that when host and viral factors were controlled, nucleotide and amino acid diversities in HCV HVR1 might not correlate well with response to IFN.