OBJECTIVETo investigate the distribution of hepatitis C virus (HCV) subtypes among intravenous drug users (IDUs) in Kunming, Yunnan province, in 2014.

METHODSA total of 276 plasma samples were collected from IDUs in Kunming during April 2014 -July 2014, in which 199 plasma samples were tested to be HCV antibody positive. For the HCV antibody positive samples, HCV E1E2 genes and NS5B genes were amplified by using nested-polymerase chain reaction (PCR). After sequencing, the HCV subtypes were determined through phylogenetic analysis.

RESULTSBased on the phylogenetic trees of E1E2 gene and NS5B gene fragments, a total of 125 samples were genotyped. 3b was the predominant subtype (48.8%,61/125), followed by 3a (30.4%, 38/125), 6n (14.4%, 18/125), 6a (3.2%, 4/125) and 1b (3.2%, 4/125). The distributions of HCV subtypes by sex, marital status, ethnic group and HIV-1 infection status showed no statistical differences. However, the distribution of HCV subtypes by age showed statistical difference, the diversity of HCV subtypes was found in age group <45 years. The genetic distances of 3a, 3b and 6a on E1E2 and NS5B were larger than those of 1b and 6n. For genotype 3, the genetic distances of 3b on E1E2 and NS5B were larger than those of 3a.

CONCLUSIONFive HCV subtypes were found among IDUs in Kunming, HCV subtypes 3b and 3a were predominant, which have circulated in this population for long time.