A high affinity phage-displayed peptide as a recognition probe for the detection of Salmonella Typhimurium

• A phage-displayed peptide, NFMESLPRLGMH (pep49) is explored for the specific detection of Salmonella Typhimurium.
• The specificity of pep49 stems from its interaction with abequose residues in the O-antigen of S. Typhimurium.
• An ELISA assay using pep49 was able to detect S. Typhimurium at a concentration of 103 CFU/mL.

Salmonellosis is one of the most common and widely distributed foodborne diseases. A sensitive and robust detection method of Salmonella Typhimurium (S. Typhimurium) in food can critically prevent a disease outbreak. In this work, the use of phage displayed peptides was explored for the detection of S. Typhimurium. A phage-displayed random dodecapeptide library was subjected to biopanning against lipopolysaccharide (LPS) of S. Typhimurium. The peptide NFMESLPRLGMH (pep49) derived from biopanning displayed a high affinity (25.8 nM) for the LPS of S. Typhimurium and low cross-reactivity with other strains of Salmonella and related Gram-negative bacteria. Molecular insights into the interaction of pep49 with the LPS of S. Typhimurium was gleaned using atomistic molecular dynamics simulations and docking. It was deduced that the specificity of pep49 with S. Typhimurium LPS originated from the interactions of pep49 with abequose that is found only in the O-antigen of S. Typhimurium. Further, pep49 was able to detect S. Typhimurium at a LOD of 103 CFU/mL using ELISA, and may be a potential cost efficient alternative to antibodies.