High prevalence of the B2+C2 subgenotype mixture in patients with chronic hepatitis B in Eastern China

Aim: To investigate the prevalence of hepatitis B virus (HBV) genotype mixtures among patients with chronic hepatitis B (CHB) in Eastern China. Methods: A total of 4908 chronic HBV patients from Eastern China were enrolled. HBV genotypes and subgenotypes were determined using a multiplex PCR technique. Serum viral loads and hepatitis B e antigen (HBeAg) levels detected using real-time fluorescent quantitative PCR and ELISA assay, respectively. The presence of precore/basic core promoter (PC/BCP) mutations was examined with PCR and direct sequencing of the amplified products. Results: HBV genotypes B, C, D, B+C, and B+D were found in 19.21%, 64.75%, 1.49%, 13.63%, and 0.92% of the patients, respectively. In 669 patients with the genotype mixture B+C, the subgenotypes B2+C2 and B2+C1 accounted for 68.13% and 31.87%, respectively, no other subgenotypes were identified. HBV B+C was more frequent in the patients with moderate CHB than in patients with mild CHB. In patients with moderate CHB, the subgenotype mixture B2+C2 was lower than B2+C1 (51.97% vs 63.38%), while the opposite situation was found in patients with severe CHB (22.15% vs 15.49%). The highest average viral load was found in patients with the genotype B+C mixture. The prevalence of HBV B2+C2 increased in patients from 50 to 59 years of age and was significantly different from the proportion of patients in the same age group with genotype B (23.2% vs 15.2%). A double mutation (G1896A) in the PC was significantly more common in subgenotype B2+C2 than in subgenotype B2+C1. Conclusion: The HBV B2+C2 subgenotype was prevalent in CH patients with a high HBV replication status and correlated with a more severe course of the disease.