title: [Types and emergence time of YMDD motif mutation in hepatitis B virus polymerase gene during lamivudine treatment].
abstract: OBJECTIVE
  To study the types and emergence time of YMDD motif mutation in hepatitis B virus (HBV) polymerase gene during lamivudine treatment.
  
  
  METHODS
  The serum samples were collected from 33 patients with HBV DNA rebounding and 2 non-responders after at least one year lamivudine treatment. HBV polymerase gene was amplificated by PCR, then the products were detected by restriction fragment length polymorphism (RFLP) and by direct sequence analysis.
  
  
  RESULTS
  The variants with YMDD mutation were 14 out of the 35 patients. Mutation patterns detected in these patients included four YIDD, six YVDD, three YI/VDD and one YI/MDD. The mean emergence time of YMDD variants was 11.07+/-3.65 months after the treatment, and the earliest one and the latest one occurred 5 months and 17 months after the treatment respectively. The emergence times of YIDD, YVDD, YI/VDD were (10.00 +/- 1.41) months, (11.67 +/- 4.41) months and (13.33 +/- 3.31) months respectively, which had no statistical significance (F = 0.543, P < 0.05). Three patients treated with lamivudine 200 mg every day after the mutation were followed up for 6 months, whose HBV variants had not vanished.
  
  
  CONCLUSIONS
  There are many kinds of HBV variants after lamivudine treatment, including YIDD, YVDD, YI/VDD and YI/MDD. The emergence time of variants is quite variable between different types and the mean time is (11.07 +/- 3.65) months after treatment, and there is no relationship between the type of YMDD mutation and the time of lamivudine administration.
authors.affiliation: Department of Infectious Diseases, First Affiliated Hospital, Medical College of Zhejiang University, Hangzhou 310003, China.
authors.forename: Wei-feng
authors.initials: WF
authors.lastname: Liang
authors.forename: Dan-hong
authors.initials: DH
authors.lastname: Yang
authors.forename: Yue-hong
authors.initials: YH
authors.lastname: Shen
authors.forename: Yuan-jun
authors.initials: YJ
authors.lastname: Xie
authors.forename: Nian-feng
authors.initials: NF
authors.lastname: Zhao
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D020816:Amino Acid Motifs / Q000235:genetics; D002648:Child; D003001:Cloning, Molecular; D004279:DNA, Viral / Q000235:genetics; D024882:Drug Resistance, Viral / Q000235:genetics; D005260:Female; D015684:Gene Products, pol / Q000235:genetics*; D006515:Hepatitis B virus / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D019259:Lamivudine / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D012194:RNA-Directed DNA Polymerase / Q000235:genetics; D013997:Time Factors
chemical_list: D004279:DNA, Viral; D015684:Gene Products, pol; C066027:P protein, Hepatitis B virus; D019259:Lamivudine; D012194:RNA-Directed DNA Polymerase