High-efficacy IgY for prophylaxis and therapy against Helicobacter pylori through synergistic multi-epitope immunogen design, sequential immunization, and targeted gastric delivery

Helicobacter pylori is classified as a Class I carcinogen by the World Health Organization (WHO) and infects nearly 50% of the global population. Egg yolk immunoglobulin (IgY) possesses therapeutic potential and has been recognized as a promising alternative to antibiotics. In this study, seven dominant H. pylori virulence factors (FlaA, VacA, HpaA, Nap, BabA, SabA, and UreB) were selected to construct three multi-epitope recombinant proteins (MERPs), which were successfully expressed, purified, and used for hen immunization. Sequential immunization (SqI) with MERPs elicited significantly higher anti-H. pylori IgY titers than single-antigen regimens (MERP1–3). The purified IgY demonstrated high specificity without cross-reactivity to other bacteria, strong neutralizing activity, and effective inhibition of bacterial growth, urease activity, and adhesion to AGS cells and mucin. To enhance IgY stability under gastric conditions, a chitosan-coated alginate microbead delivery system was employed for encapsulation. This formulation effectively protected IgY in simulated gastric fluid (SGF), preserved its immunoreactivity, and enabled controlled release.  In vivo, specific IgY improved survival, weight gain, and gastric histology in infected mice, while reducing bacterial load, urease activity, and proinflammatory cytokines (TNF-α, IL-1β, IL-6, IL-17). It also upregulated epithelial markers (β-catenin, Ki-67, ZO-1, Occludin), indicating enhanced barrier integrity and reduced apoptosis. Overall, these findings demonstrate that multi-epitope antigen design combined with sequential immunization and protective delivery enhances IgY efficacy, supporting its potential as a prophylactic and therapeutic strategy against H. pylori infection.