immunogenic potential of chitosan nanoparticles encapsulating recombinant slyb antigen of enterotoxigenic escherichia coli (etec) in an animal model

Intestinal bacterial infections are a significant cause of mortality in developing countries, with enterotoxigenic escherichia coli (etec) being a leading cause of severe diarrheal diseases. these infections are characterized by the production of enterotoxins and colonization factors that disrupt the small intestine, leading to diarrhea. while antibiotic treatments face limitations, vaccination has emerged as a critical tool for prevention. this study evaluates the immunogenicity of chitosan nanoparticles (nps) encapsulating the recombinant surface antigen slyb of etec in an animal model.the slyb antigen was expressed in an expression vector, purified, and encapsulated into chitosan nanoparticles using the ionic gelation method. rabbits were immunized using three administration methods: oral, oral-injection, and injection. antibody levels in serum and feces were measured via elisa, and the neutralization ability of immune sera was assessed using an ileal loop assay.results demonstrated significant titers of serum igg and fecal iga antibodies across all immunized groups, with the oral administration of chitosan nanoparticles eliciting the highest iga responses in mucosal surfaces. encapsulation of the recombinant slyb protein in chitosan nps enhanced antigen stability, promoted controlled release, and stimulated robust cellular and humoral immunity. the challenge test confirmed the efficacy of immune sera in neutralizing etec toxins, particularly in orally vaccinated groups.this study highlights the potential of chitosan nanoparticles as an effective delivery platform for mucosal vaccines against etec. by encapsulating recombinant antigens, this method not only enhances immunogenicity but also offers a promising alternative to conventional vaccination strategies for diarrheal diseases. further research is recommended to explore scalability and efficacy in broader populations.