Positional effect of mutations in 5'UTR of hepatitis C virus 4a on patients' response to therapy.

Aim: To investigate the effects of mutations in domain III of the hepatitis C virus (HCV) internal ribosome entry sequences (IRES) on the response of chronic HCV genotype 4a patients to interferon therapy.

Methods: HCV RNA was extracted from 19 chronic HCV 4a patients receiving interferon/ribavirin therapy who showed dramatic differences in their response to combination therapy after initial viral clearance. IRES domain III was cloned and 15 clones for each patient were sequenced.