Adenine ; analogs & derivatives ; pharmacology ; Drug Resistance, Viral ; Hepatitis B virus ; drug effects ; Humans ; Organophosphonates ; pharmacology

Objective To establish a convenient,accurate and practical method for detection of adefovir dipivoxil resistance-as- sociated mutation in hepatitis B virus:rtA181V/T/S and rtN236T mutations.Methods According to HBV complete sequences in GenBank,two pairs of primers were designed to amplify the region of HBV reverse transcriptase in order to introduce a BglI restriction site upon PCR product of wild type (wt) and a BseDI restriction site upon PCR product of rt236 mutant type.After amplification,the PCR products were digested with BglI and BseDI separately.We used this method to detect wild,rt181 mu- tant,rt236 mutant plasmids and 3 chronic hepatitis B patients' serum with obvious ADV resistance-associated mutations.We also tested the sensitivity of this method by mixing the wild and mutant plasmids in different proportions.Results The method could detect rt181 and rt236 mutations simultaneously.The result of RFLP analysis was in accordance with that of DNA se- quencing and cloning analysis.This method could detect the mutants even when they comprised only 10% of the total virus population.Conclusions The PCR-RFLP method with high sensitivity can detect rt181 and rt236 mutations simultaneously.It can be used for early detection of ADV resistance-associated mutation in hepatitis B virus.

OBJECTIVETo study the resistant rate of hepatitis B virus (HBV) to ADV and the dynamic evolution of HBV in lamivudine (Lam)-resistant chronic hepatitis B (CHB) patients.

METHODSTwenty-three Lam-resistant CHB patients were assigned to a 10mg/d ADV monotherapy for 68-116 weeks. The baseline and different time point blood samples after ADV monotherapy were analyzed for ADV-resistant mutations using direct sequencing of PCR products; the evolution of HBV mutations was examined by clonal analysis of serial samples from one patient infected with ADV-associated resistant HBV strains.

RESULTSThe cumulative incidence of genotypic ADV resistance at weeks 48 and 96 was 4.3% and 10.5% respectively respectively. The evolution analysis of HBV mutant strains in an ADV-resistant CHB patient showed that the proportion of YMDD mutants gradually decreased with rtA181S mutants increasing over time after ADV monotherapy, and that rtA181S+N236T mutants became the predominant strains during prolonged ADV monotherapy. The addition of Lam to the ongoing ADV treatment had poorer antiviral response in the patient with rtA181S or rtA181S+N236T mutant infection; one clone with multi-drug resistant mutations was selected during Lam and ADV combination therapy.

CONCLUSIONIncreased risk of adefovir resistance and selection of multi-drug resistant mutations are associated with long-term ADV monotherapy in patients with Lam-resistant chronic hepatitis B.

Adenine ; analogs & derivatives ; therapeutic use ; Adult ; Antiviral Agents ; therapeutic use ; Drug Resistance, Viral ; Evolution, Molecular ; Female ; Hepatitis B virus ; classification ; drug effects ; genetics ; Hepatitis B, Chronic ; drug therapy ; virology ; Humans ; Lamivudine ; pharmacology ; Male ; Middle Aged ; Organophosphonates ; therapeutic use