Immunogenic Potential of a Multi-Peptide Vaccine Construct Against Uropathogenic Escherichia coli-Associated Urinary Tract Infection.

Background: Urinary tract infection caused by uropathogenic E. coli (UPEC) is a common infectious disease. The growing frequency of antibiotic resistance highlights the need for alternative strategies, such as vaccines, to combat UTIs. This study aimed to evaluate the immunogenicity of a novel vaccine candidate targeting UPEC. Methods: Different bioinformatics servers were used to design a vaccine candidate composed of PapG II and FimH antigens from UPEC, along with the N- (1-173) and C-terminal (401-495) domains of FliC from Salmonella typhimurium. The final construct was cloned into the pET28a vector, expressed, purified, and confirmed using SDS-PAGE and Western blotting. Mice were immunized with the recombinant protein, both with and without alum adjuvant, and antibody responses were measured using ELISA. Results: The final vaccine construct included one domain of PapG II (81 aa) and FimH (83 aa). The conserved domains of FliC were incorporated into the construct. SDS-PAGE and Western blot confirmed the purification of the protein, with a size of 53 kDa. Immunization of mice with PapG.FimH.FliC protein induced significantly higher levels of serum IgG, IgG isotypes, IgA, as well as mucosal IgA and IgG responses compared to the controls (p < 0.05). The addition of alum to the protein significantly enhanced serum IgG1 and IgA and mucosal IgG, compared to the protein without alum (p < 0.05). Conclusion: The vaccine construct induced significant humoral responses in the mouse model, suggesting its potential as a promising candidate against UPEC. However, additional experimental analyses are required to validate the efficacy of the vaccine construct.