The Study Of Molecular Epidemiology Among Injecting Drug Users In Yunnan Province

Hepatitis C is a major cause of acute hepatitis and chronic liver disease, including cirrhosis and liver cancer. It is estimated that 170 million people are chronically infected with HCV all over the world, and the natural infection rate of hepatitis C virus (HCV) in China is 3.2%. Because of no effective medicine or vaccine, hepatitis C has become one of the most severe diseases. For the same transmission route of human immunodeficiency virus (HIV), the rate of HCV co-infection is very high among HIV-1 infected individuals, especially among injecting drug users (IDUs). Injection drug use is the most important risk factor for HIV/HCV co-infection in China, so it's very significative to study the molecular epidemiology of HCV among IDUs co-infected with HIV and HCV in Yunnan province.During replication of HCV, RNA-dependent RNA polymerase (RdRp) frequently introduces random nucleotide errors, which results in a relatively high rate of spontaneous nucleotide substitutions. By phylogenetic analysis of 5'NC, E and NS5B region, HCV can be divided into 6 major genotypes and each genotype has several subtypes. Since HCV genotype or subtype impacts its pathogenicity and responses to treatment directly, it is useful and necessary to analyze the genotype or subtype of HCV.In this study, the HCV genotype or subtype of 52 HIV/HCV co-infected individuals from Dehong, Honghe, Wenshan, Qujing, Kunming and Dali regions were determined by sequencing part of HCV NS5B gene. Several sample were also determined by sequencing parts of HCV C and E gene. By comparing with the genotyping results based on 5'NCR, the following results were concluded. First of all, genotyping method based on HCV 5'NCR can't accurately distinguish between HCV genotype 1 and 6. Secondly, HCV genotype 3 was the predominant genotype among IDUs in Yunnan province. Genotype 6 and mixed infection were also major genotypes in this group. Additionally, the distribution of HCV genotypes or subtypes in this group was different from the main land of China, butfamiliar with neighbor countries, such as Thailand and Burma. This result suggested that the spread of HCV among IDUs was associated with the overland heroin transport routes, which was the same as HIV. Thirdly, high rate mixed infection of HCV and two novel subtypes of HCV genotype 6 were identified among this group, which indicated the complexity of HCV prevalence among IDUs.In summary, HCV molecular epidemiology among IDUs co-infected with HIV and HCV in Yunnan province has been investigated in this study, the results of which will provide basis for the therapy, diagnosis, vaccine research and prophylaxis of HIV/HCV co-infection.