OBJECTIVETo understand the genotype characteristics and its evolution of patients with poor response to initial combined treatment of Lamivudine and Adefovir dipivoxil for chronic hepatitis B.

METHODSWe detected the HBV genotypes of three patients-S1, S2, S3, who with poor response to initial treatment of Lamivudine and Adefovir dipivoxil for chronic hepatitis B over 12 months by the application of cloning and sequencing method at the time point of baseline,4 weeks after treatment, 12 weeks, 24 weeks, 48 weeks, 60 weeks. 25 clones were randomly selected to identify and sequence at each time point.

RESULTSThe total number of clones from 3 patients with poor response to initial combined treatment of Lamivudine and Adefovir dipivoxil for chronic hepatitis B at each time point was 398. About patient S1 at baseline, genotype C accounting for 8.3%, genotype B, for 91.7%, so genotype B was in dominant (22/24). But genotype C has gradually developed to 100% after treatment for 60 weeks. About patient S2 and S3, genotype B was the only type at baseline. However type B has gradually "drift" to type C during treatment. When treatment for 60 weeks, type C has taken the absolute advantage 75% for S2, and 100% for S3.

CONCLUSIONSThe cloning and sequencing can represent the overall genotype level better. HBV genotype has performed the evolution trend that genotype has drifted from B to C during long-term drug pressure, which is the main reason for poor response to initial combined treatment of Lamivudine and Adefovir dipivoxil for chronic hepatitis B.