中国生物工程杂志

To develop an oral vaccine against Helicobacter pylori infection, the H.pylori napA gene, encoding the neutrophil-activating protein (NAP), was expressed in a live delivery vehicle lactococcus lactis. And the immunogenicity of the recombinant NAP was evaluated after the lactococcus lactis was administrated orally into mice. First, the napA gene of Helicobacter pylori was cloned into the prokaryotic expressive vector pNICE:sec. Second, the recombinant vector pNICE:sec-nap was transformated into Lactococcus lactis strain NZ9000 to express NAP protein. Then the recombinant NAP was induced to express and was identified by SDS-PAGE and Western-bloting. Finally, ICR mice were randomly divided into 4 groups and administrated orally with PBS, L.lactis pNICE:sec, L.lactis pNICE:sec-nap, and the inactivated H.pylori respectively. The specific IgG and IgA were identified after 7 times immunization. The results we got in this experiment were described as follows. The napA was amplified and cloned in the vector pNICE:sec successfully. The fusion protein (17kDa) was expressed in L.lactis by the induction of the nisin. The quantity of expression accounted for 9.5% of the total bacterial protein. Western bolt analysis confirmed that fusion protein could be recognized specifically by the serum of anti-H.pylori. Anti-NAP IgG titers in the serum of L.lactis pNICE:sec-nap group was higher than the L.lactis pNICE:sec group and no obviously difference with the inactivated H.pylori. The anti-NAP IgA titer in the intestinal mucosa of L.lactis pNICE:sec-nap group was higher than other groups. These results suggest that the recombinant L.lactis which expresses napA, may be applicable as an oral vaccine to induce protective immunity against H.pylori.