Hepatitis C virus genotype distribution in Myanmar: Predominance of genotype 6 and existence of new genotype 6 subtype

Aim: This study was performed to determine the prevalence and distribution of hepatitis C virus (HCV) genotypes in Myanmar. Methods: A total of 1333 peripheral blood samples were collected from four different border cities of Myanmar. The anti-HCV antibody-positive serum samples were identified. HCV was genotyped by reverse transcriptase polymerase chain reaction, direct DNA sequencing and phylogenetic analysis on the partial core genome. Results: The overall prevalence of HCV infection was 11.6% (154/1333). Regionally, it was 13.5% (47/349) in the north-eastern city, 12.8% (64/501) in the north-western city, 4.2% (16/380) in the southern city and 26.2% (27/103) in the western city. HCV was genotyped in 145/154 (94.2%) samples. Genotype 6 was the most prevalent genotype in this study (71/145, 49%), followed by genotype 3 (57/145, 39.3%), genotype 1 (16/145, 11%), and genotype 2 (1/145, 0.7%). Genotype 6 was mostly found in the northern cities and genotype 3 in the southern and western cities of Myanmar. Multiple HCV genotypes/subtypes were successfully characterized as 1a, 1b, 2a, 3a, 3b, 6m, 6n, and a new 6 subtype. Among them, subtype 6n was the most predominant subtype (38.6%), followed by subtype 3b (29.7%), 3a (9.6%), 6m (9%), 1b (6.9%), 1a (4.1%), new 6 subtype (1.4%) and 2a (0.7%). Subtype 6n was more widely distributed in the northern cities whereas subtype 3b was more common in the western city. The newly discovered genotype 6 subtype was from the northern cities. Conclusions: The results indicate there are regional differences of HCV genotype distribution in Myanmar. There is a distinct geographic variation from other South-East Asian countries in terms of the existence of the new genotype 6 subtype.