Clearance of serum hepatitis C virus RNA after interferon therapy in relation to virus genotype.

The effect of recombinant interferon-alfa on serum HCV RNA levels in Japanese patients with chronic hepatitis C was investigated. At 24 weeks of treatment, 41 (32.5%) of 126 patients lost HCV RNA from serum, and aminotransferases were normalized in 31 (75.6%) of these 41 cases. HCV genotypes were categorized into four types (Type I, II, III, IV); the frequencies among the patients were: Type I: 0%, Type II: 70.6%, Type III: 20.6%, and Type IV: 6.3%. At the end of the 24-week treatment, HCV RNA levels were remarkably decreased in Type III patients and became undetectable in 18 (69.2%) of 26. In contrast, only 18 (20.2%) of 89 patients with Type II and two of eight with Type IV lost HCV RNA from sera. The relation between HCV genotype (Type III) and response to IFN therapy was also confirmed using a logistic regression model. HCV genotype seems to be an important factor in determining the response to IFN in patients with chronic hepatitis C.