YMDD Mutation and Genotype of HBV

OBJECTIVE To determine the relationship between YMDD mutations of hepatitis B virus(HBV) and HBV genotypes during lamivudine treatment.METHODS HBV genotypes were determined by nested PCR with six pairs of HBV genotype-specific primers(A to F).Then YMDD mutations were detected by real-time fluorometry PCR in plasma specimens from 175 hepatitis B patients receiving lamivudine antiviral therapy.RESULTS Among 175 plasma specimens,16 samples were with genotype B(9.1%),155 samples were with genotype C(88.6%) and 4 samples were with genotype D(2.3%).Among 175 plasma specimens,103 YMDD mutations were found(58.9%).The YMDD mutation rates were 62.5% and 58.1% in genotypes B and C respectively.There was no significant difference in YMDD mutation rate between genotypes B and C(χ2=0.02,P=0.90.05).Genotype B with YMDD mutations in 10 samples were found,including 2 YIDD(M+I) mutations and 8 YVDD(M+V) mutations.Genotype C with YMDD mutations in 68 samples were found,including 44 mutations I(M+I) and 24 mutations V(M+V).There was significant difference in YMDD mutation types between genotypes B and C(χ2=5.5,P0.05).CONCLUSIONS Our results indicated that the YMDD mutation rate is 58.9% after 2-4 years with lamivudine treatment.YMDD mutation rate and YMDD mutation types have significant difference between genotypes B and C of HBV.