DIFFERENCES IN THE HEPATITIS-C VIRUS GENOTYPES IN DIFFERENT COUNTRIES

We recently classified the hepatitis C virus (HCV) into 4 types (HCV-PT, -K1, -K2a and -K2b) according to differences in nucleotide sequences. it was found that HCV-PT, the prototype reported from the U.S.A., was rare in Japan, suggesting that distribution of HCV genotypes may be different in various countries. The prevalence of HCV genotypes was therefore compared in different countries. Genotyping of HCV was performed by slot-blot hybridization analysis using cDNA probes specific to each type of HCV or by restriction fragment length polymorphism analysis. In 121 Japanese non-cancer patients, the prevalence of HCV genotypes was 77.7% for HCV-K1, 16.5% for HCV-K2a and 5.0% for HCV-K2b. HCV-PT was detected in only 1 patient (0.8%). The prevalence in 43 Japanese hepatocellular carcinoma (HCC) patients was 74.4% for HCV-KI, 18.6% for HCV-K2a and 4.7% for HCV-K2b. HCV-PT was found in only 1 sample. In 19 European non-cancer patients, HCV-PT was found in 42.1% and HCV-K1 was found in 52.6%. HCV-K2 was not found. All 7 samples from European HCC patients were HCV-K1, indicating a significantly higher prevalence than in non-cancer patients. In 13 Brazilian non-cancer patients, the distribution pattern was similar to that of the Europeans. In 10 samples from the U.S.A., HCV-PT was found in 70% and HCV-K2 was found in 1 sample. In 18 Chinese noncancer patients, HCV-K1 was found in 44.4%, HCV-K2a in 50.0% and HCV-K2b in 5.6%. HCV-PT was not found. Two samples from Chinese HCC patients were HCV-K1. These results indicate that the distribution patterns of HCV genotypes vary widely among different countries. Prevalence of HCV-K1 was high in every country except for the U.S.A., suggesting that HCV-KI may be the major type of HCV worldwide. HCV-PT was occasionally found in the Japanese and Chinese samples but was more common in the samples from Western countries. On the other hand, HCV-K2 was rarely found in samples from Western countries but was commonly found in the Japanese and Chinese samples. These differences suggest that HCV-PT may be the Western type and HCV-K2 may be the Oriental type.