A new type of hepatitis C virus in patients in Thailand.

Partial nucleotide sequences in the tentative NS5 region of the hepatitis C viral genome obtained from patients with chronic hepatitis in Thailand were analyzed by reverse transcription followed by the polymerase chain reaction. Of ten samples studied, four showed low homologies to any known type of HCV: the homologies of the nucleotide sequences of these clones with HCV-J, -US, -K2a and -K2b were 66.5-69.1%, 66.5-68.2%, 61.2-64.1% and 64.4-66.2%, respectively, and the homologies of their deduced amino acids sequences were 71.7-75.2%, 71.7-75.2%, 69.0-72.6% and 69.9-73.5%, respectively. These four clones were classified a new distinct type of HCV, named HCV-T. Moreover, the nucleotide and amino acid sequence homologies of the four HCV-T clones showed that the HCV-T type could be classified into two genotypes, HCV-Ta and HCV-Tb.