OBJECTIVESTo evaluate the three different methods in monitoring the lamivudine-resistant HBV mutants in lamivudine-treated patients with chronic hepatitis B.

METHODSThe sensitivity and specialty of melting curve assay and polymerase chain reaction microplate nucleotide hybridization-enzyme linked immunosorbent assay (PCRmnh-ELISA) were compared with those of mismatch polymerase chain reaction-restriction fragment length polymorphism (mPCR-RFLP) and sequence analysis, through detection of HBV YMDD mutants in 44 serums from chronic hepatitis B patients receiving lamivudine monotherapy at the time of viral breakthrough.

RESULTSmPCR-RFLP assay was more sensitive (10(4) copies/ml) than both PCRmnh-ELISA (10(5) copies/ml) and melting curve assay (10(6) copies/ml). 26 YMDD mutants and 18 wild-types were determined by the means of mPCR-RFLP. Among the 26 mutants, only 16 and 18 mutants were found by melting curve assay and PCRmnh-ELISA, respectively. Whereas, out of the 18 wild-types, 2 and 13 mutants were detected by melting curve assay and PCRmnh-ELISA, respectively. To confirm the different results determined by the three methods in 16 samples, sequence analysis was conducted and showed that the rate of consistency with sequencing was 93.8% by mPCR-RFLP, 43.8% by melting curve, and 18.8% by PCRmnh-ELISA, respectively (chi2=18.7, P<0.01).

CONCLUSIONSThe mPCR-RFLP assay is reliable to monitor HBV YMDD mutations. Melting curve assay and PCRmnh-ELISA should be further improved to increase their sensitivity and specialty.