title: [Distribution of lamivudine- resistant variants in hepatitis B virus].
abstract: To observe the distribution of HBV variants resistant to lamivudine and their relation to clinical manifestations of chronic hepatitis.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors.affiliation: The Sir Run Run Shaw Hospital, College of Medicine, Zhejiang University, Hangzhou 310016, China.
authors.forename: Guan-guan
authors.initials: GG
authors.lastname: Su
authors.forename: Dan-hong
authors.initials: DH
authors.lastname: Yang
authors.forename: Nian-feng
authors.initials: NF
authors.lastname: Zhao
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D024882:Drug Resistance, Viral; D014644:Genetic Variation; D006515:Hepatitis B virus / Q000187:drug effects* / Q000235:genetics; D019259:Lamivudine / Q000494:pharmacology*
chemical_list: D000998:Antiviral Agents; D019259:Lamivudine