High rate of mixed genotypes of hepatitis C virus in patients of an epidemic area in Japan.

The subjects of this study were 151 patients (69 males and 82 females) who underwent examination and liver biopsy owing to liver dysfunction in an epidemic area with hepatitis C. Second generation hepatitis C virus antibody (HCV Ab) was positive in 116 (76.8%) of 151 cases. HCV-RNA was detected in 120 (79.5%) by polymerase chain reaction (PCR). In 7 (4.6%) cases, HCV Ab could not be found, but HCV-RNA was detected. Three (2.0%) cases were positive for HCV Ab but negative for HCV-RNA. On the basis of variation in nucleotide sequence within a restricted region in the putative core gene of HCV, HCV genotypes were classed into four types of I, II, III and IV by PCR. The genotypes were identified in 120 cases. Ninety-eight (81.7%) cases carried one of the four types. Type II was found in 76 (63.3%) cases and type III in 22 (18.3%). The other 22 (18.3%) carried simultaneously two different genotypes (mixed type): 21 (17.5%) cases with type II + III and one (0.8%) case with type II + IV. In comparison with the incidence of HCV mixed types in cases with hepatitis C in a non-epidemic area, carriers of mixed types were found at a significantly higher rate in the epidemic area. Liver biopsy of 120 cases with identified HCV genotypes in the epidemic area showed 93 cases of chronic active hepatitis, nine of chronic lobular hepatitis, 10 of chronic persistent hepatitis and eight of liver cirrhosis. No significant correlation could be detected between liver histology and HCV genotypes.(ABSTRACT TRUNCATED AT 250 WORDS)