OBJECTIVETo explore the characteristics of mutation in HBV polymerase (P) gene reverse transcriptase region (RT region) in lamivudine-resistant chronic hepatitis B (CHB) patients.

METHODSThis study involved 115 CHB patients who developed clinical resistance to lamivudine. Direct sequencing of the PCR products was used to detect lamivudine genotypic resistance.

RESULTSLamivudine resistant mutation was detected in 103 patients, and the major mutations included rtL180M+rtM204V and rtM204I, accounting for 58.3% and 22.3%, respectively. Other resistant substitutions included rtL80V/I, rtT184S, and rtA200V, and combined mutation of triple resistant substitutions was detected in HBV RT region of 5 patients by direct sequencing.

CONCLUSIONFor lamivudine-treated patients, combined mutation at the sites other than rtL180 and rtM204 in HBV P gene should also be detected for drug resistance evaluation.