title: Hepatitis-B-virus resistance to lamivudine given for recurrent infection after orthotopic liver transplantation.
abstract: BACKGROUND
  Orthotopic liver transplantation for end-stage hepatitis-B-virus (HBV) infection is commonly complicated by recurrence of HBV. Lamivudine, a cytosine nucleoside analogue, has been shown to suppress HBV infection. We report the development of resistance to lamivudine in three patients who underwent transplantation for end-stage liver disease secondary to hepatitis B.
  
  
  METHODS
  Two of the patients received lamivudine for recurrent HBV infection after transplantation, whereas the third patient began treatment 1 month before transplantation in an attempt to prevent HBV recurrence after transplantation. The three patients initially responded well to treatment, but viral recurrence occurred after 9-10 months of treatment in all patients. HBV DNA was amplified from serum and sequenced through a conserved polymerase domain-the tyrosine, methionine, aspartate, aspartate (YMDD) locus. We assessed the susceptibility of HBV to lamivudine by infecting primary human hepatocytes with serum taken before the start of treatment and after recurrence in varying concentrations of lamivudine.
  
  
  RESULTS
  DNA sequencing showed a common mutation within the YMDD locus of the HBV polymerase gene in all patients during lamivudine treatment. In hepatocyte cultures infected with pretreatment serum, HBV DNA concentrations were reduced to less than 6% of those in control cultures by addition of lamivudine in concentrations as low as 0.03 mumol/L. By contrast, in cultures treated with serum taken after recurrence, HBV DNA concentrations did not fall below 20% of control values, even with lamivudine at 30 mumol/L.
  
  
  CONCLUSIONS
  Resistance to lamivudine has been reported in HIV patients with mutations in the YMDD locus of the polymerase gene. Our findings indicate a common mechanism of lamivudine resistance for HIV and HBV that involves similar point mutations in homologous domains of the viral polymerases.
authors.affiliation: Division of Hepatology, University of Miami School of Medicine, Florida, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Bartholomew
authors.forename: R W
authors.initials: RW
authors.lastname: Jansen
authors.forename: L J
authors.initials: LJ
authors.lastname: Jeffers
authors.forename: K R
authors.initials: KR
authors.lastname: Reddy
authors.forename: L C
authors.initials: LC
authors.lastname: Johnson
authors.forename: H
authors.initials: H
authors.lastname: Bunzendahl
authors.forename: L D
authors.initials: LD
authors.lastname: Condreay
authors.forename: A G
authors.initials: AG
authors.lastname: Tzakis
authors.forename: E R
authors.initials: ER
authors.lastname: Schiff
authors.forename: N A
authors.initials: NA
authors.lastname: Brown
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D004279:DNA, Viral / Q000032:analysis; D004259:DNA-Directed DNA Polymerase / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D006509:Hepatitis B / Q000150:complications / Q000188:drug therapy* / Q000821:virology; D006515:Hepatitis B virus / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D006801:Humans; D019259:Lamivudine / Q000494:pharmacology* / Q000627:therapeutic use; D017093:Liver Failure / Q000209:etiology / Q000601:surgery; D016031:Liver Transplantation; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D012008:Recurrence
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D019259:Lamivudine; D004259:DNA-Directed DNA Polymerase