Effects of genotypes of hepatitis C virus on interferon treatment for chronic type C hepatitis

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Abstract
Interferon is commonly used for treatment of type C hepatitis, but the effects are variable and many factors may be responsible. Hepatitis C virus (HCV) can be classified into 4 types, PT, Kl, K2a and K2b. Therefore, the responses to interferon treatment in patients with the different HCV genotypes were analyzed. Twenty-four patients with type C hepatitis were treated with 3 to 10 million units of various types of interferon for more than 8 weeks. HCV-RNA encoding the NS5 region (HCV-NS5) was positive in these 24 patients, 16 of which were classified with the Kl type and 8 with the K2 type of HCV. In all patients except for 2, HCV-NS5 became negative within 3 weeks of treatment without relation to the HCV genotypes. Serum alanine aminotransferase levels were normalized in 7 out of 8 patients in the K2 group and in 4 out of 16 patients in the Kl group at the end of 8 weeks. At the 24th week, ALT levels were normalized in 5 out of 6 patients in the K2 group, and in one out of 9 patients in the K1 group. The percentage of patients exhibiting a good response was significantly higher in the K2 group than in the K1 group at both observation periods. During the post-treatment periods, relapse following complete response was found in 3 patients in the K2 group and in one patient in the K1 group. The final effects of interferon were significantly better in the K2 group than in the K1 group. These results indicate that the effects of interferon were significantly better in patients in the K2 group than in patients in the K1 group. Normalization of serum ALT levels was found in two patients with cirrhosis in the K2 group, but in none of the cirrhosis patients in the Kl group, suggesting that effects of interferon may not be related to the progression of liver disease in patients in the K2 group. These results suggest that genotypes of HCV are one of the major determinants of the effect of interferon treatment.