RESUMO
Objective To identify whether rtL180M+A186T+M204V mutation is a novel entecavir (ETV)-resistant mutation. Methods A total of 12 708 patients in the Fifth Medical Center of Chinese PLA General Hospital from July 2011 to July 2016 were enrolled in this study. Drug resistance mutation in reverse transcriptase region (RT) were analyzed by direct sequencing and verified by clonal sequencing if rtL180M+A186T+M204V has been detected (≥20 clones/sample); 1.1-mer HBV replicons harboring wild-type or mutant RT gene were constructed respectively and transfected into HepG2 cells for phenotypic analysis. Results ETV experienced patients were detected in 4047 of total patients. Among these patients, classical ETV-resistant mutation of HBV and rtL180M+A186T+M204V mutation were detected in 795(19.64%) and 7(0.17%), respectively. The rtL180M+A186T+M204V mutant was consistent with the features of ETV-resistant mutation: all the rtA186T-positive patients had a history of lamivudine exposure prior to ETV treatment; the emergence of the mutations was associated with virological breakthrough or inadequate virological response to ETV; phenotypic analysis showed that patient-derived rtL180M+A186T+M204V mutant exhibited 13.3% replication capacity and 210.2-fold decreased susceptibility to ETV compared to the wild-type strain, while the mutant remained sensitive to tenofovir (TDF). Conclusions rtL180M+A186T+M204V as a novel ETV-resistance mutation has a low clinical detection rate, which is related to the markedly reduced replication capacity of the mutant. TDF-based rescue therapy should be considered for patients harboring rtL180M+A186T+M204V mutation in clinical practice.