[Distribution of lamivudine- resistant variants in hepatitis B virus].

OBJECTIVE: To observe the distribution of HBV variants resistant to lamivudine and their relation to clinical manifestations of chronic hepatitis. METHODS: Using direct sequencing, YMDD (tyrosine-methionine-aspartate-aspartate) variants in patients with chronic HBV were detected before and during treatment with lamivudine. A statistical analysis of the distribution of HBV strains resistant to lamivudine was performed. RESULT: Four variant strains existed in patients before lamivudine treatment, 128 variant resistant strains were noted after 6 mouths of lamivudine treatment including 42 YVDD (valine) variants, 20 YIDD (isoleusine) variants and 66 non-YMDD variants. According to the hepatitis severity, 8 patients were mild, 108 moderate and 12 severe. Viral loading was higher and clinical types were more severe in no-YMDD variants. CONCLUSION: Variant strains including strains resistant to lamivudine exist naturally before lamivudine treatment, but lamivudine-resistant ones become more dominant after treatment. Liver inflammation is more severe in non-YMDD group.