Resistant mutants induced by adefovir dipivoxil in hepatitis B virus isolates

AIM:To investigate the loci of adefovir dipivoxil(ADV)-induced resistance in hepatitis B virus(HBV)isolates and optimize the management of ADV-treated patients.METHODS:Between June 2008 and August 2010,a cross-sectional control study was conducted comprising 79 patients with chronic HBV infection-related liver disease who had been administered ADV monotherapy.Patients underwent liver imaging.Serum DNA extracts were analyzed for HBV DNA levels,genotypes,and serology markers,and deep sequencing of the HBV P gene was performed.RESULTS:ADV-resistant patients were found either with a single mutated locus,or with coexisting mutated loci.The most prevalent mutations were rt A181T,rt V214A,and rt N236T.Twenty-six patients had more than two mutated loci.The mutants were distributed among the patients without any significant affinity for gender,age,end-stage of liver disease,complications of non-alcoholic fatty liver disease,or HBV DNA levels.Patients with the rt A181T mutant were primarily infected with genotype C and e-antigen negative HBV,while patients with the rt N236T mutant were primarily infected by genotype B HBV(χ2=6.004,7.159;P=0.023,0.007).The duration of treatment with ADV was shorter in the single mutant group compared with the multi-mutant group(t=2.426,P=0.018).CONCLUSION:Drug-resistant HBV mutants are complex and diverse.Patients should receive the standard and first-line antiviral treatment,strictly comply with medication dosage,and avoid short-term withdrawal.