Immuno-Bioinformatics Study of Autotransporter Protein, Antigen 43, in Enterotoxigenic Escherichia coli Isolated From Calves

Extensive effort is focused on identifying genomic conserved antigens in development of effective vaccine against Enterotoxigenic Escherichia coli. Antigen 43 is one of the members of a large secreted protein family named autotransporters in the E.coli and other gram negative bacteria. Autotransporter proteins have a similar conserved structure. Some of them are recognized during both experimental and naturally occurring ETEC infections. Antigen 43 is represented as a potential target in vaccine development because of its virulence functions such as cell aggregation, biofilm formation and its presence in convalescent sera from human patients with ETEC diarrhea. In this study, we carefully investigate antigenic structure and immunogenicity of the Antigen 43 protein of strain 510 E.coli isolated from calves by experimental methods and immunoinformatics tools. Amino acid sequence, physico-chemical parameters, stability, secondary and tertiary protein structure, the ability of induction the B and T cell immune responses by having the effective epitopes and also the allergenicity assessment were analyzed. In this study, we identified 15 peptide sequences that can potentially induce B and T cell immune responses and finally, 9 of them were introduced as antigens. The results of in-silico analysis on this protein suggested that it can be used in bovine colibacillosis vaccine development.