Evaluation of the Effectiveness of Polyclonal Antibody Developed against a Recombinant Multi-Epitope Protein Composed of Uropathogenic Escherichia coli Antigens

Uropathogenic Escherichia coli (UPEC) is the main cause of urinary tract infections (UTIs). Increasing antibiotic resistance among UPEC isolates complicate UTI treatment in the future. Finding alternative approaches against UPECs seems necessary. Despite many efforts to develop a vaccine for UPEC, there is no yet effective vaccine against the bacteria.

Designing a multi-epitope vaccine based on the main UPEC virulence factors can be an effective strategy for prevention of UTI. In the previous study, three important proteins from UPEC strains including FimH, FyuA and CNF-1 were selected to design a multi-epitope antigen which was used for production of polyclonal antibody in rabbits. In the present study, the collected sera were used for evaluating the sensitivity, specificity, cell adherence, and biofilm inhibition of the developed polyclonal antibody.

ELISA results showed high binding activity of the rabbit polyclonal antibody against the multi-epitope protein even in low antibody titers. In addition, the polyclonal antibody showed antigenic specificity against the multi-epitope protein and UPEC UTI89 strain. Cross-reactivity of the polyclonal antibody was observed with Klebsiella pneumonia. Bacterial adhesion was reduced significantly in the presence of antibody, compared to the controls.

The generated polyclonal antibody significantly reduced in vitro biofilm formation of UTI89 strain while did not significantly affect the biofilm degradation. These results highlight the potential of the designed multi-epitope protein as a promising vaccine candidate for the prevention of UTI caused by UPEC.