Immunoinformatics aided design of a peptide-based kit for detecting Escherichia coli O157:H7 from food sources

Abstract

Food and water-borne enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is a zoonotic bacterium that causes gastroenteritis and other human diseases. It has also been linked to chronic foodborne diseases with high mortality rates worldwide, particularly in children. Hence, this study was carried out to designed a peptide base kit for quick detection of E. coli in food. A peptide-based rapid detection kit was designed using an immunoinformatic technique and some antigenic target genes (stx1A, stx2B, escC, fliC, and eae). The antigenic gene sequences retrieved were screened for antigenicity, transmembrane topology, B-cells and helper T-cells. Selected epitopes were joined with appropriate linkers to form a chimeric protein which consists of five B-cell epitopes, five interleukin-4 (IL-4) inducer epitopes and five interleukin-10 (IL-10) inducer epitopes. The improved and optimized chimeric protein sequence was cloned in-silico in a suitable expression host, E. coli-strain K12. The designed peptide refined and validated tertiary structure was molecularly docked with the tertiary structures of each antigenic target gene. The physicochemical properties of the chimeric protein showed that the construct has an amino acid length of 295 amino acids, a molecular weight of 29.876 kiloDalton (kDa), an aliphatic index of 75.05 and an instability index of 14.82 which confers stability. The construct was hydrophilic with a GRAVY value of −0.261 and had a considerable half-life of 4.4 h (mammalian reticulocytes, in vitro), >20 h (yeast, in vivo) and >10 h (E. coli, in vivo). Conclusively, the final construct has successfully met the design requirements for the development of a lateral flow kit, which has the potential to provide fast and efficient detection of E. coli O157:H7. However, it is the additional validation through the vitro and in vivo techniques needed to confirm that this designed peptide based test kit.