Delivery of Helicobacter pylori HpaA to gastrointestinal mucosal immune sites using Lactococcus lactis and its immune efficacy in mice

Objective To develop a safe and effective oral vaccine against Helicobacter pylori using its HpaA protein expressed in Lactococcus lactis . Results The gene encoding HpaA was obtained by PCR and ligated to pNZ8110-lysM following digestion with Nae I + Sph I. The recombinant plasmid was transferred into E. coli for multiplication, and then into L. lactis . The recombinant L. lactis was induced to express HpaA, resulting in two products of 29 and 25 kDa, both of which yielded positive immunoreaction with mouse antisera against H. pylori , as confirmed by immunoblot assays. The 29 kDa product constituted 12% of the cell lysates. Oral inoculation with the engineered L. lactis evoked significantly elevated serum IgG level in mice (P