OBJECTIVETo investigate the mutations in Polymerase region and hepatitis B virus (HBV) genotypes in chronic hepatitis B patients with poor response to Lamivudine treatment.

METHODS631 chronic hepatitis B patients with poor response to Lamivudine were recruited in this study. Real-time PCR and DNA sequencing were used to determine HBV genotypes; direct sequencing was performed to detect mutations, and real-time PCR was used to quantify HBV DNA load. Mutations in polymerase region were investigated in different HBV genotypes.

RESULTS272 patients were infected with HBV of genotype B, and 359 patients were infected with HBV of genotype C. The mean age of patients infected with HBV of genotype C (39.1+/-11.4 years old) were significant higher than that of patients infected with HBV of genotype B (33.7+/-9.7 years old) (t = -6.55, P less than 0.01). The patients infected with HBV of genotype C had relatively higher HBV DNA load [(5.96+/-1.22) log10 copies/ml] than the patients infected with HBV of genotype B [(5.58+/-1.21) log10 copies/ml] (t = -2.01, P less than 0.05). The overall incidence rate of A181V/T mutation in genotype C (5.3%) was significantly higher than that in genotype B (0.4%) (x2=12.23, P less than 0.01), but the incidence rate of M204I/V, L180M, T184A/G/I/S, S202G/I and V173L mutations was not significantly different between genotype B and C (each P more than 0.05). M204I mutation in genotype B (20.6%) was more frequent than that in genotype C (13.9%) (x2=4.91, P less than 0.05). The Lamivudine resistance mutations were not significantly different between genotype B and genotype C (x2 = 0.00, P more than 0.05).

CONCLUSIONSThe incidence rate of lamivudine resistance mutation is not significantly different between genotype B and genotype C, but patients infected with HBV of genotype C have higher HBV DNA load than patients infected with HBV of genotype B.