[Establishment of stable expression cell lines for HBsAg variants and analysis of antigenicity].
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.
Wang
Zhan-hui
ZH
The School of Life Sciences of Wuhan University 430072, China.
Qi
Yi-peng
YP
Lin
Yu-long
YL
Luo
Kang-xian
KX
Hou
Jin-lin
JL
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
D006514:Hepatitis B Surface Antigens