Molecular characterization of hepatitis C virus genotype 6 subtypes in Thai blood donors.

BACKGROUND: Hepatitis C virus (HCV) genotype is important for identifying effective antiviral therapy, evaluating pathogenic severity, and tracking transmission routes. In Thailand, HCV genotypes 3 and 1 are the most common. We have previously demonstrated an increasing appearance of genotype 6 in HCV infections in Thailand. However, only limited epidemiological data on genotype 6 in Thailand are available. This study aimed to characterize HCV genotype 6 among apparently healthy Thai blood donors.

METHODS: In total, 240 blood samples were collected from Phitsanulok Regional Blood Center, Phitsanulok, Thailand. RNA was reverse transcribed and amplified by the nested polymerase chain reaction. HCV genotyping was performed by direct sequencing and phylogenetic tree analysis of core sequences. Amino acid polymorphism of various subtypes of HCV genotype 6 was investigated.

RESULTS: Of the 240 samples, 192 were successfully sequenced for the core region and 84 were determined to be of HCV genotype 6 by phylogenetic analysis. The most prevalent HCV-6 subtypes were 6f > 6n > 6c > 6i. Amino acid sequences of the partial core region among these four subtypes differed by one to seven residues.

CONCLUSION: For HCV-6, the subtype 6f was commonly found in Thai blood donors. Comparison of core protein from various HCV-6 subtypes showed substantial polymorphisms, which may form the basis of future studies using samples from patients with clear HCV histories. This feature can be applied to therapies tailored to particular genotype variants.