RESUMO
<p><b>OBJECTIVE</b>To investigate the relationship between lamivudine-resistant mutants of hepatitis B virus (HBV) and serum HBV DNA loading before antiviral therapy.</p><p><b>METHODS</b>This study involved 106 patients with hepatitis B receiving lamivudine treatment for an average of 32 months (rang 12-48 months). Serum HBV DNA loadings were measured with PCR before and every 4 to 6 months during lamivudine therapy. HBV YMDD mutants were detected using mismatched PCR-restriction fragment length polymorphism (PCR-RFLP) during lamivudine treatment.</p><p><b>RESULTS</b>HBV DNA loading was significantly higher in patients infected with HBV YMDD mutants during lamivudine therapy than those infected with HBV without YMDD mutation.</p><p><b>CONCLUSION</b>High viral loading in hepatitis B patients before treatment is associated with high likeliness of HBV YMDD mutation during lamivudine treatment. HBV DNA loading may be indicative for the occurrence of YMDD mutation during lamivudine therapy.</p>