ABSTRACT
<p><b>BACKGROUND</b>To investigate the mutation of HBV polymerase gene in chronic hepatitis B patients treated with lamivudine.</p><p><b>METHODS</b>The restriction-fragment-length-polymorphism (RFLP) assay for HBV DNA sequence determination at the codon 528 and 552 in the HBV polymerase gene associated with lamivudine resistance in vitro. HBV DNA samples extracted from sera of 240 patients were subjected to PCR amplification with primer pairs F2/R2 (552), F3/R2 (528). Each PCR product was digested with Nde I or Nla III.</p><p><b>RESULTS</b>Serum HBV DNA mutation was found in 51/240 patients (38/51M552V, 26/38L528M, 13/51M552I) after therapy for 52 weeks. DNA sequence analysis was performed on samples of 3 patients, and the results were consistent with those of RFLP assay.</p><p><b>CONCLUSION</b>The RFLP assay was able to detect the mutation of HBV DNA at codon 552 and 528 which are the principal site of HBV DNA resistant to lamivudine. The specific PCR method for HBV DNA mutation is rapid, simple and specific.</p>