Establishment of a method for classification of HBV genome and it′s application

Objective By using the techniques of PCR and restriction fragment length polymorphism (RFLP), we established a classification method for HBV genome based on viral S gene of asymptomatic HBV carriers (AsC).Methods By using this method we classified HBV DNA of AsC living in Guangzhou, Shenyang, Beijing and Chongqing.Results Among the AsC of Guangzhou, genotype B was 32.8%, genotype C 42.7%, mixed genotypes B and C 23.0%, others 1.6%;among the AsC of Chongqing, genotype B was 35.0%, genotype C 40.0%, mixed genotypes B and C 25.0%; among the AsC of Beijing, genotype B was 25.0%, genotype C 50.0%, mixed genotypes B and C 25.0%; among the AsC of Shenyang, genotype B was 11.1%, genotype C 88.9%. The prevalent HBV strains in China are genotype C and genotype B, and genotype C is the main genotype in west China. Conclusion The established method for genotyping is simple and convenient. Using this method, we also classified HBV DNA of the patients with chronic hepatitis B and liver cirrhosis living in Guangzhou, and found that mixed genotypes B and C was in 50.0% of the patients detected, suggesting the mixed infection might lead to a severe damage of the liver tissue.