title: Molecular characterization of hepatitis B virus surface antigen mutants in Singapore patients with hepatocellular carcinoma and hepatitis B virus carriers negative for HBsAg but positive for anti-HBs and anti-HBc.
abstract: OBJECTIVE
  Mutations on the a-determinant of hepatitis B virus surface antigen (HBsAg), capable of escaping detection and vaccination, are identified in HBsAg-positive/anti-HBs-positive vaccinated infants. We studied the prevalence of these mutants in HBsAg-negative/anti-HBc-positive chronic HBV carriers and patients with hepatocellular carcinoma (HCC).
  
  
  METHODS
  DNA sequence coding for the antigenic a-determinant of HBsAg was amplified from either HCC genomic DNA or serum samples of the selected patients and sequenced. The replicative mutant genomes were reconstituted in vitro and their reactivity to commercial kits measured.
  
  
  RESULTS
  Mutations within and/or outside the a-determinant were identified in patients seronegative for HBsAg. They were then reconstituted in vitro and transiently transfected into HepG2 cells. Culture medium containing secreted HBV viral particles was collected and assayed for their binding to commercial kits. Drastic decrease of reactivity to these kits was seen with most of the identified mutations, including those located outside the a-determinant.
  
  
  CONCLUSIONS
  The existence of a more complex antigenic structure of HBsAg is indicated by the decreased reactivity to detection of mutations, some of which are outside the a-determinant, escape vaccination and may persist in seronegative patients. The high proportion of HBsAg mutants that are integrated in HCC genomes suggests a role of these mutants in hepatocarcinogenesis, possibly leading to mutant HBV-related HCC.
authors.affiliation: Department of Clinical Research, Singapore General Hospital, Ministry of the Environment, Singapore.
authors.forename: Chong Jin
authors.initials: CJ
authors.lastname: Oon
authors.forename: Wei Ning
authors.initials: WN
authors.lastname: Chen
authors.forename: Kee Tai
authors.initials: KT
authors.lastname: Goh
authors.forename: Steven
authors.initials: S
authors.lastname: Mesenas
authors.forename: Han Seong
authors.initials: HS
authors.lastname: Ng
authors.forename: Gilbert
authors.initials: G
authors.lastname: Chiang
authors.forename: Clarence
authors.initials: C
authors.lastname: Tan
authors.forename: Shiuan
authors.initials: S
authors.lastname: Koh
authors.forename: Siaw Wei
authors.initials: SW
authors.lastname: Teng
authors.forename: Ivy
authors.initials: I
authors.lastname: Toh
authors.forename: Mei Chung
authors.initials: MC
authors.lastname: Moh
authors.forename: Kian Sim
authors.initials: KS
authors.lastname: Goo
authors.forename: Kaeling
authors.initials: K
authors.lastname: Tan
authors.forename: Ai Lin
authors.initials: AL
authors.lastname: Leong
authors.forename: Gek San
authors.initials: GS
authors.lastname: Tan
mesh_terms: D000293:Adolescent; D000328:Adult; D006528:Carcinoma, Hepatocellular / Q000097:blood* / Q000453:epidemiology / Q000235:genetics*; D002353:Carrier State / Q000097:blood* / Q000453:epidemiology; D002675:Child, Preschool; D005260:Female; D006509:Hepatitis B / Q000097:blood* / Q000453:epidemiology / Q000235:genetics*; D006510:Hepatitis B Antibodies / Q000097:blood* / Q000235:genetics*; D006514:Hepatitis B Surface Antigens / Q000097:blood* / Q000235:genetics*; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D007223:Infant; D008113:Liver Neoplasms / Q000097:blood* / Q000453:epidemiology / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D012698:Serologic Tests; D012846:Singapore / Q000453:epidemiology
chemical_list: D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens