A shift in the hepatitis C virus genotype dominance in blood donor samples from Thailand.

Hepatitis C virus (HCV) can be classified into six major genotypes. The HCV genotypes variability accounts for its geographical distribution, its responses to treatments and the clinical outcomes. The aim of this study was to determine the distribution of HCV genotypes among volunteer blood donors in Thailand. Samples from 135 anti-HCV positive blood donors were analyzed. HCV RNA and genotyping was carried out using nested polymerase chain reaction (PCR) and genotype-specific primer PCR for a portion of the core region. HCV RNA was detected in 109 samples (80.7%). Genotype analysis demonstrated four different genotypes. The most common was genotype 3a (36.7%), followed by genotype 6 (29.4%), 1a (19.3%), 1b (6.4%) and mixed infection (1.8%). Seven samples were untyped (6.4%) in the present study. In several previous reports, the prevalence found in Thailand was HCV genotypes 3, 1 and 6. The present results show an increasing importance of the genotype 6 in HCV infections. This study has also described for the first time in Thailand mixed infections of HCV genotypes.