A study of recombinant protective H.pylori antigens.

Aim: To construct a recombinant vector which can express M (r)26000 outer membrane protein (OMP) from Helicobacter pylori (Hp), and to obtain the vaccine protecting against Hp infection and a diagnostic reagent kit quickly detecting Hp infection.

Methods: The gene encoding the structural M(r)26000 outer membrane protein of Hp was amplified from Hp chromosomal DNA by PCR, and inserted in the prokaryotic expression vector pET32a (+), which was transformed into the Top10 E. coli strain. Recombinant vector was selected, identified and transformed into BL-21(DE3) E. coli strain. The recombinant fusion proteins were expressed. The antigenicity of recombinant protein was studied by ELISA or immunoblotting and immunized Balb/c mice.

Results: The gene of M(r)26000 OMP was amplified to be 594 base pairs, 1.1% of the cloned genes was mutated and 1.51% of amino acid residues was changed, but there was homogeneity between them. The recombinant fusion protein encoded objective polypeptides of 198 amino acid residues, corresponding to calculated molecular masses of M (r)26000. The level of soluble expression products was about 38.96% of the total cell protein. After purification by Ni-NTA agarose resin columniation, the purity of objective protein became about 90%. The ELISA results showed that recombinant fusion protein could be recognized by patient serum infected with Hp and rabbit serum immunized with the recombinant protein. Furthermore,Balb/c mice immunized with the recombinant protein were protected against H.pylori infection.

Conclusion: M (r)26000 OMP may be a candidate vaccine preventing Hp infection.