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) that encapsulates 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 different 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. The study's findings revealed that the oral administration of chitosan nanoparticles led to the highest titers of serum IgG and fecal IgA antibodies, suggesting a potential for enhanced mucosal immune responses.The encapsulation of the recombinant SlyB protein within the chitosan nanoparticles not only maintained antigen stability but also promoted controlled release, thereby stimulating robust cellular and humoral immunity.The efficacy of immune sera in neutralizing ETEC toxins was confirmed through a challenge test, with the oral vaccination group demonstrating the most significant neutralizing activity. This study underscores 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.