title: Wild-type and 'a' epitope variants in chronic hepatitis B virus carriers positive for hepatitis B surface antigen and antibody.
abstract: OBJECTIVE
  This study aims to examine the genomic variants of the 'a' epitope in chronic hepatitis B virus (HBV) carriers positive for both hepatitis B surface antigen (HBsAg) and antibody to HBsAg (anti-HBs).
  
  
  METHODS
  Eighteen HBV carriers were studied. Hepatitis B virus (HBV) DNA was extracted and the 'a' epitope region was amplified and sequenced.
  
  
  RESULTS
  Eighteen Chinese asymptomatic HBV carriers were studied. There were 13 patients who were positive for both HBsAg and anti-HBs. Of these, one patient had only wild-type HBV, three had a viral mixture, and five had only 'a' epitope variant HBV. Of the three patients with a viral mixture, all had variants in the less conserved region (123-137). Of the five patients with pure HBsAg mutants, three had variants in the less conserved region while two had variants in the highly conserved region. In this study with a limited number of patients, the serum alanine aminotransferase (ALT) levels were higher in patients with wild-type HBV, compared with those with either 'a' epitope variants or a viral mixture consisting of wild type and variants.
  
  
  CONCLUSIONS
  Eight of the nine (89%) patients positive for both HBsAg and anti-HBs harbored an 'a' epitope variant. The lower ALT levels seen in patients who had either pure 'a' epitope variant or a mixture of wild type and mutants suggest that a closer monitoring of these 'a' epitope variants should be required, as patients carrying these infectious viral strains may remain asymptomatic.
authors.affiliation: Department of Gastroenterology, Singapore General Hospital. smesenas@hotmail.com
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Mesenas
authors.forename: Wan C
authors.initials: WC
authors.lastname: Chow
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhao
authors.forename: Gek K
authors.initials: GK
authors.lastname: Lim
authors.forename: Chong J
authors.initials: CJ
authors.lastname: Oon
authors.forename: Han S
authors.initials: HS
authors.lastname: Ng
mesh_terms: D000328:Adult; D000368:Aged; D000940:Antigenic Variation; D002353:Carrier State / Q000821:virology*; D004279:DNA, Viral / Q000032:analysis; D000939:Epitopes; D005260:Female; D006510:Hepatitis B Antibodies / Q000097:blood*; D006514:Hepatitis B Surface Antigens / Q000097:blood* / Q000276:immunology*; D006515:Hepatitis B virus / Q000235:genetics / Q000276:immunology*; D019694:Hepatitis B, Chronic / Q000821:virology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D004279:DNA, Viral; D000939:Epitopes; D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens