Oral Immunization with Recombinant Lactobacillus acidophilus Expressing the Adhesin Hp0410 of Helicobacter pylori Induces Mucosal and Systemic Immune Responses

Helicobacter pylori infection is relatively common worldwide and is closely related to gastric mucosa-associated lymphoid tissue (MALT) lymphoma, chronic gastritis, and stomach ulcers. Therefore, a safe and effective method for preventingH. pylori infec-tion is urgently needed. Given that developing an effective vaccine againstH. pylori is one of the best alternatives,H. pylori ad-hesin Hp0410 was expressed in the food-grade bacterium Lactobacillus acidophilus. The recombinant live bacterial vaccine was then used to orally vaccinate mice, and the immunoprotective effects of Hp0410-producing strains were investigated.H. pylori colonization in the stomach of mice immunized with the recombinant L. acidophiluswas significantly reduced, in comparison with that in control groups. Furthermore, mucosal secretory IgA antibodies were elicited in the mucosal tissue of mice immu-nized with the recombinant bacteria, and specific anti-Hp0410 IgG responses were also detected in mouse serum. There was a significant increase in the level of protection against gastricHelicobacter infection following a challenge withH. pylori Sydney strain 1 (SS1). Our results collectively indicate that adhesin Hp0410 is a promising candidate vaccine antigen, and recombinant L. acidophilus expressing Hp0410 is likely to constitute an effective, low-cost, live bacterial vaccine againstH. pylori. Helicobacter pylori is a Gram-negative bacterium found in dif-ferent areas of the stomach, especially in the antrum. Approx-imately 50 % of the world’s population is infected by the pathogen and up to 64 % of China’s population (1, 2). H. pylori infections typically commence during childhood and last for life. The infec