[Polymerase region mutations and hepatitis B virus genotypes in chronic hepatitis B patients with poor response to lamivudine].

OBJECTIVE: To investigate the mutations in Polymerase region and hepatitis B virus (HBV) genotypes in chronic hepatitis B patients with poor response to Lamivudine treatment. METHODS: 631 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. RESULTS: 272 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). CONCLUSIONS: The 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.