Aim: To express fusion protein of the cholera toxin B subunit (ctB) and the urea membrane channel gene (ure I) of H. pylori in E. coli, and analyze its immunogenicity.
Methods: The prokaryotic expression vector pET32a+/ctB/ure I was constructed by inserting ctB gene amplified by PCR into the 5' terminus of ure I gene of expression vector pET32a+/ure I. The fusion gene was verified by endonuclease digestion and sequence analysis. The fusion protein ctB/ure I was expressed in E. coli BL21(DE3), purified by His-HP affinity chromatography, and analyzed by SDS-PAGE, Western blot and Pro-gel analyzer 4.0. The mice were immunized with purified ctB/ure I, and the immunoreactivity with ctB and ure I of the murine sera was analyzed by indirect ELISA.
Results: The pET32a+/ctB/ure I expression vector was constructed successfully and confirmed by endonuclease digestion and sequence analysis. The expressed ctB/ure I protein with molecular weight about 58,000 was shown when induced with 1 mmol/L IPTG for 4 h at 22 degrees C, and the protein could react with horse anti-ctB and human anti-ure I sera when detected with Western blot, and the purity of the purified protein was about 94.3%. The sera from mice immunized with purified ctB/ure I protein could react with ctB, ure I, and ctB/ure I when detected with indirect ELISA.
Conclusion: The fusion protein expression vector pET32a+/ctB/ure I was constructed successfully. The fusion protein ctB/ure I was shown to have immunoreactivity with both anti-ctB and anti-ure I anti-sera, and could evoke production of anti-ctB and anti-ure I antibody in mice. Our work established a good foundation for further study on the new and effective H. pylori vaccines.