[The cloning, expression, purification and immunological identification of wild-type and mutant hepatitis B virus X gene in pGEX-6P-2 system].
To settle the foundation for the future research on the influence of wild and mutant (A1762T/ G1764A) HBV X gene on the progress of chronic HBV infection and hepatic tumorigenicity, wild and mutant (A1762T/G1764A) HBxAgs expression system was constructed. The wild and mutant (A1762T/ G1764A) HBV X genes were amplified with polymerase chain reaction (PCR) from HBV genome were inserted into pGEX-6P-2 and confirmed by sequencing respectively. Prokaryotic expression vectors pGEX-6P-2-hbvx(w) and pGEX-6P-2-hbvx(m) (A1762T/G1764A) were constructed and transformed to Trans1-blue; wild and mutant HBxAgs were expressed through IPTG induction respectively; after refolding of inclusion body, the wild and mutant HBxAgs were purified with GSTrap FF; and analysised by SDS-PAGE, Western blot and ELISA. SDS-PAGE analysis showed that the expression system was able to express target protein efficiently; the concentrations of purified wild HBxAg and mutant HBxAg were 4.88 mg/mL and 5.07 mg/mL respectively; Western blot analysis certified both the wild HBxAg and the mutant HBxAg could be recognized by the same monoclonal antibody against HBxAg; the two expressed fusion antigens coated in microtiter plate were able to react with the sera of HBV infected patients but not with the sera from healthy donors in ELISA. Results demonstrated that we successfully established a system for expression of hepatitis B x antigen and lay the foundation for further research on the role and molecular mechanisms of the mutant HBxAg in the progress of chronic HBV infection and hepatic tumorigenicity.