Hepatitis B Virus Mutation Pattern RtA181S+T184I+M204I May Contribute To Multidrug Resistance In Clinical Practice:Analysis Of A Large Cohort Of Chinese Patients

ObjectiveThe study aimed to characterize the prevalence and virological features of the rtA181S+T184I+M204I mutant in HBV reverse transcriptase region in a large cohort of patients with chronic HBV infection.MethodsIn total,22,009 nucleoside/nucleotide analog(NAs)-treated patients who underwent resistance testing at Fifth Medical Center of Chinese PLA General Hospital(Original name Beijing 302 Hospital)between July 2007 and June 2016 were enrolled.The clinical data and serum samples were collected for HBV reverse-transcriptase gene sequencing.rtA181S-related mutation patterns and classical NAs mutation patterns were analyzed and cloning sequencing(?20 clones/sample)was performed to the mutation samples of rtA181S+T184I+M204I with the highest detection rate.Phenotypic analysis of the viral replication capacity and drug susceptibility was performed.ResultsThe rtA181 S mutation was detected in 0.82%(180/22009)of samples.rtA181S-positive patients had significantly higher lamivudine(LAM),adefovir(ADV),and entecavir(ETV)exposure than rtA181S-negative patients.Of 180 rtA181S-positive patients,138 had coexistent resistance mutations,34 had coexisting LAM-resistance mutation(LAMr),17 had coexisting ADV-resistance mutation(ADVr),and 87 had coexisting ETV-resistance mutation(ETVr),including one case of ADVr+ETVr.rtA181S+T184I+M204I occurred in 78.2%(68/87)of rtA181S+ETVr patients and 37.8%(73/180)of all rtA181S-positive patients.Longitudinal analysis of the clinical course of resistance mutant evolution for representative cases showed that rtA181S+T184I+M204I developed in all patients who had received LAM/telbivudine?ADV and was receiving ETV or ADV+ETV,accompanied by virological breakthrough or inadequate virological response.Compared with wild-type,the rtA181S+T184I+M204I mutant had 53.7% lower replication capacity and more than 1000-,3.9-,and 383.3-fold greater LAM,ADV,and ETV resistance,respectively,but remained sensitive to tenofovir.Artificial elimination of rtA181 S from the rtA181S+T184I+M204I mutant restored viral susceptibility to ADV but decreased viral replication capacity.ConclusionsOur study presented the first evidence that the HBV rtA181S+T184I+M204I mutation as a novel multidrug-resistance mutation,which is related to the LAM/LdT,ADV,ETV sequential or combined treatment.TDF-or ETV+TDF-based rescue therapy should be considered for patients harboring this mutation in clinical practice.