Greater diversity of hepatitis C virus genotypes found in Hong Kong than in mainland China.

A hepatitis C virus (HCV) genotyping PCR assay based on type-specific primers was expanded to include genotype 6a as well as genotypes 1a, 1b, 2a, and 3a. The nucleotide sequences of a 194-bp fragment in the center of the HCV core gene showed that the homologies between genotype 6a and genotypes 1a, 1b, 2a, 2b, 3a, and 5 were 81.2, 82.1, 73.8, 77.3, 81.4, and 78.9%, respectively. A high degree of homology (99.6%) was seen in the amplified core region among eight clinically unrelated genotype 6a isolates. Although the Hong Kong Chinese patients had predominantly genotype 1b (70%), it was noteworthy that genotype 6a was the second most common genotype (14%). Four other HCV genotypes--1a, 1b, 2a, and 2b--were also present. In contrast, HCV infection by mainland China was confined to genotypes 1b and 2a. Thus, we found a greater diversity of HCV genotypes in Hong Kong than in mainland China.