OBJECTIVETo investigate the clinical characteristics and the pattern of precore and core promoter mutations of hepatitis B virus (HBV) subgenotypes Ba, C1 and C2.

METHODSA cohort of 151 patients with chronic HBV infection in Guangdong province of China was enrolled in this study. HBV subgenotypes were determined by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). Precore and core promoter mutations were analysed using nucleotide sequencing.

RESULTSOf the 151 patients, 80, 51 and 20 were infected with subgenotypes Ba, C1 and C2 respectively. No significant differences were found in HBeAg positivity and liver functional indexes among these three subgenotypes when age and sex were matched. Virologically, HBV/Ba showed the highest frequency of A1896 mutation but the lowest frequency of T1762/A1764 mutation. HBV/C1 was associated with the highest tendency to develop T1762/A1764 mutation, but the lowest prevalence of A1896 mutation. HBV/C2 was associated with an intermediate tendency to develop A1896 and T1762/A1764 mutations.

CONCLUSIONDifferent mutation patterns in precore and core promoter regions are responsible for HBeAg-negative HBV infections among different subgenotypes.