Objective To study the relationship between gene mutation of 5' noncoding region (5'NCR) of hepatitis C virus (HCV) genotype 1b in infection state and effect of interferon-alpha (IFNα) on the treatment of chronic hepatitis C.Methods Sera from 9 patients were collected before, during and after IFNα therapy and sera from 40 HCV 1b patients were collected.HCV 5'NCR fragments were amplified from these samples by RT-PCR and sequenced by cutting with restriction endonuclease Mbo I and BamH I.Results There were 5 infection states in 40 patients with HCV 1b: (1) Mbo I restriction site was detected in 24 patients (24/40, 60.0%) ; (2) Mutation without Mbo I restriction site was detected in 5 patients (5/40, 12.5%) ; (3) 7 patients (7/40, 17.5%) coinfected the strain with or without of Mbo I restriction site; (4) Mutation with BamH I restriction site was detected in 2 patients (2/40, 0.5%) ; (5) 2 patients (2/40, 0.5%) presented with two Mbo I restriction sites.Then we checked the mutation of 5'noncoding region of the sera from 9 patients with IFNα therapy.In the 5 patients with sustained virological response (SVR) , 2 for HCV genotype 2a, 3 for HCV genotype 1b without Mbo I restriction site.In the 4 patietns with nonresponder, 1 for coinfection of HCV genotype 1b and 2a, 3 for HCV genotype 1b without Mbo I restriction site.Conclusion Of 40 HCV genotype 1b serum samples, 60.0% patients presented single Mbo I restriction site, suggesting the state of infection with wild type strain.
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