In Silico Characterization of Epitopes for Vaccine Design against Escherichia coli based on Heme-Utilization Protein

Introduction: E. coli heme-utilization (ChuA) protein is an outer membrane protein, which has been shown as an amenable target for vaccine design studies. In the present study, we aimed to identify and characterize the most potent B and T cell epitopes of ChuA protein to unveil its most immunogenic regions.Materials and Methods: In the present study, homology modeling was invoked to determine the three-dimensional (۳D) structure of E. coli heme-utilization protein (ChuA). Thereafter, membrane topology, ligand binding site, surface accessibility, and clefts were assigned for ChuA, Linear and conformational B cell epitopes and T cell epitopes were predicted for ChuA. The ۲D and ۳D interaction plots between the most potent T cell epitopes and HLA-A۰۲۰ and HLA-DRB۰۱۰۱ structures were drawn following the molecular docking analyses.Results: Our results indicated that ChuA is heme ligand transporter protein, which forms a common beta-barrel structure. It is located in the membrane via ۲۲ membrane-spanning regions. Residue–based pockets and clefts were identified on the ChuA protein. Immunological analyses revealed ۹ highly potent B cell epitopes. Among predicted T cell epitopes ۲ most potent epitopes were analyzed for HLA binding via molecular docking. The YSKQPGYG and FAAATTMSY epitopes showed stable interactions with HLA-A۰۲۰ and HLA-DRB۰۱۰۱.Conclusions: Our immunological, biochemical, and functional analysis highlighted the region of the ChuA protein, which harbors the highest immunogenic properties for vaccination purposes. Our strategy to employ ۳D structure prediction and epitope prediction results could be deemed as an amenable approach for efficient vaccine design in various platforms.