title: [Establishment of stable expression cell lines for HBsAg variants and analysis of antigenicity].
abstract: OBJECTIVE
  To study the mechanism of hepatitis B virus infected patients who is negative for HbsAg.
  
  
  METHODS
  DNA sequences of 46 patients were analyzed. In these patients, HBsAg was negative but HBV DNA was positive and six new HBsAg variants were identified. Four of the six variants were combined point mutants and two were insertion variants. These S genes were subcloned into eukaryotic expression vector EBO-plpp, and the recombinant eukaryotic expression plasmids were transfected into COS7 cells. Cell lines expressing mutant type HBsAg were obtained. The supernatants were detected by ELISA and RIA.
  
  
  RESULTS
  Only the two-amino acid-insertion variants could be detected and the others failed to react with polyclonal and monoclonal antibodies against HbsAg.
  
  
  CONCLUSIONS
  The results indicated that the point mutations and insertions may result in a conformational change of the S gene, which affect HBsAg antigenicity, suggesting a possible relationship between the variants and the negative conversion of HBsAg of the patients.
authors.affiliation: The School of Life Sciences of Wuhan University 430072, China.
authors.forename: Zhan-hui
authors.initials: ZH
authors.lastname: Wang
authors.forename: Yi-peng
authors.initials: YP
authors.lastname: Qi
authors.forename: Yu-long
authors.initials: YL
authors.lastname: Lin
authors.forename: Kang-xian
authors.initials: KX
authors.lastname: Luo
authors.forename: Jin-lin
authors.initials: JL
authors.lastname: Hou
mesh_terms: D000818:Animals; D000940:Antigenic Variation; D019556:COS Cells; D002522:Chlorocebus aethiops; D006514:Hepatitis B Surface Antigens / Q000235:genetics* / Q000276:immunology; D006515:Hepatitis B virus / Q000235:genetics / Q000276:immunology*; D019694:Hepatitis B, Chronic / Q000276:immunology / Q000821:virology; D006801:Humans; D010957:Plasmids / Q000235:genetics; D017354:Point Mutation; D014162:Transfection
chemical_list: D006514:Hepatitis B Surface Antigens