Abstract:Abstract AIM To develop an oral vaccine against Helicobacter pylori infection, the H. pylori hpaA gene, was expressed in a live delivery vehicle lactococcus lactis. METHODS The immunogenicity of the recombinant hpaA was evaluated after the lactococcus lactiswas administrated orally into mice. First, the hpaA gene of Helicobacter pylori was amplified by PCR and cloned into the prokaryotic expressive vector pNICE:sec. Second, the recombinantvector pNICE:sec-hpaA was transformated into Lactococcus lactis strain NZ9000 to express hpaA protein. Then the recombinant hpaA was induced to express and was identified by SDS-PAGE and Western blot. Finally, ICR mice were randomly divided into 4 groups and administrated orally with PBS, L. lactis pNICE:sec, L. lactis pNICE:sec-hpaA, and the inactivated H. pylori respectively. The specific IgG and IgA were identified after 7 times immunization. RESULTS The results were described as follows. The hpaA was amplified and cloned into the vector pNICE: sec successfully. The fusion protein (29kDa) was expressed in L. lactis by the induction of the nisin. The quantity of expression accounted for 9.3 % of the total bacterial protein. Western bolt analysis confirmed that fusion protein could be recognized specifically by the serum of anti-H. pylori. Anti-hpaA IgG titers in the serum of L. lactis pNICE: sec-hpaA group was higher than the L. lactis pNICE:sec group and no obviously difference with the inactivated H. pylori. The anti-hpaA IgA titer in the intestinal mucosa of L lactis pNICE:sec-hpaA group was higher than other groups. CONCLUSION The results suggest that the recombinant L. lactis which expresses hpaA, may be applicable as an oral vaccine to induce protective immunity against H. pylori.