A food-grade engineered Lactococcus lactis strain delivering Helicobacter pylori Lpp20 alleviates bacterial infection in H. pylori-challenged mice

Objective To construct a food-grade bacterium producing and delivering H. pylori Lpp20 antigen and evaluate its immune efficacy against H. pylori challenges with aim to develop anti- H. pylori oral vaccines and functional foods. Results Lpp20 was expressed as a 22 kDa protein in Lactococcus lactis , constituting 11.2% of the cell lysate proteins, and recognized by mouse antisera. Mice orally gavaged with the engineered bacterium had elevated serum IgG levels and lowered urease activity of stomach following H. pylori challenges. Conclusions This study firstly reports a food-grade L. lactis strain delivering Lpp20 to mucosal immunization sites, demonstrating a novel efficient production and safe utilization mode of Lpp20, offering a promising vaccine candidate and health food sources.