MUTATIONS OF HEPATITIS-C VIRUS 1B NS5A-2209-2248 AMINO-ACID-SEQUENCE DO NOT PREDICT THE RESPONSE TO RECOMBINANT INTERFERON-ALFA THERAPY IN FRENCH PATIENTS

Background/Aims: Studies of HCV quasispecies during interferon treatme nt have shown the selection of resistant clones, Enomoto et al. have d efined the interferon sensitivity determining region in an amino acid stretch of the HCV-1b NS5A region. Patients with a mutant strain befor e treatment were complete responders, whereas those with wild-type HCV -J strain were resistant to interferon. The same region nas studied in HCV isolates of French patients. Methods: Forty-three HCV-1b chronica lly infected patients, consisting of 26 non-responders and 17 complete responders to interferon-alfa treatment (3 MUI tiw for 6 months), wer e included retrospectively. We directly sequenced the NS5A(2209-2248) HCV region of these patients before treatment. The viral load could be obtained from sis complete responders and 15 nonresponders. Results: We detected wild-type and intermediate strains, but only two mutant st rains were present, One of them was found in a non-responder. In three complete responders, we found a wild-type strain. The distribution of the various strains was rather different from that found in Japan. Be fore treatment, the viral load was loner in complete responders (p=0.0 1). Conclusions: Only two mutant strains were detected in our study. T his could partially explain the low response rate to interferon treatm ent of French HCV-1b-infected patients, although the dose regimen was lower than in Japanese studies. Also wild-type strains were found in s ome complete responders, and no correlation was determined between the mutation number in the NS5A(2209-2248) region and response to alfa in terferon therapy. This may be related to epidemiological differences b etween HCV-1b strains present in France and those in Japan. Searching for the mutant NS5A pattern before treatment does not appear to be use ful in French patients as it is too uncommon.