identification of drug resistant mutants of hbv (hepatitis b virus) by direct sequencing in iranian patients treated with lamivudine

background and aims: lamivudine is amongst the antiviral for drug chronic hepatitis b treatment. during therapy with lamivudine, variants may emerge with ymdd mutation in the reverse transcriptase (rt) region of polymerase gene. this mutation might have a role in drug resistant for hbv. materials and methods: hbv dna extraction from serum sample of 88 patients, were subjected to nested pcr for surface gene that overlaps the rt region of polymerase. then, direct sequencing was carried out on the pcr products to identify the possible mutation. results: 32 samples were positive for pcr. direct sequencing analysis showed point mutations in ymdd motif in 9 (28%) of the specimens. these mutations were i/v replacing for the wild type (m). also, there were some compensatory mutations within the overlapping surface gene. conclusion: mutations inside ymdd motifs may influence drug attachment to the virus, hence causing drug-resistance.