[Homology of Chinese, Japanese, and American strains of hepatitis C virus].

As we know, the main HCV strain in Japan (HCV-J 4) is highly diverse in sequence from the original American strain (HCV-US). By comparing the sequences of these two strains, a region, located in the 3'-terminus of the putative E gene in HCV genome, was selected for PCR amplification. In this region, the Japanese strain showed high diversity from the American strain. From 4 patients, 8 isolates with the length of 277 bp, were cloned and sequenced. The homology of these 8 clones was high, indicating that these clones were in the same strain. This strain might be the major strain in China, named HCV-CHN1 in this paper. Since there were still many varieties in these 8 clones, HCV CHN1 could be possibly divided into 3 substrains. HCV-CHN1 was also found to be similar to HCV-J 4, with nucleotide homology of 83.4-86.3%, and amino acid homology of 78.3-88.0%, but remote from HCV-US, with homologies of only 68.6-72.6% and 69.6-73.9%, respectively. These results might be of paramount significance in developing the detection method for HCV infection and in preparing HCV vaccine.