Detection of Some Enteric Bacterial Toxin Via Modified ELISA Assay

Heat-labile enterotoxin (LT) of Enterotoxigenic Escherichia coli (ETEC) and Shiga toxin (Stx) of Shigella dysenteriae serotype 1 are two important toxins of food-borne pathogens associated with diarrheal disease. These agents have been recognized as the first leading causes of neonatal diarrhea and the Hemolytic-Uremic Syndrome (HUS). These toxins have two subunits, A and B, that B subunit can be used as a diagnostic tool. In this study, the LTB and STXB genes were amplified by using the Polymerase Chain Reaction (PCR) technique and cloned into the prokaryotic expression vector. Following the expression of recombinant LTB and STXB proteins, mouse polyclonal anti recombinant LT enterotoxin and Shiga toxin B subunits were produced for immunological detection. An Enzyme-Linked Immunosorbent Assay (ELISA) was developed for detecting toxins using clinical samples. Our results showed that the competitive ELISA has high specificity. In addition, the detection limits for LTB and STXB were 20 ng and 90 ng, respectively. Our findings revealed that the B subunit of LT and STX can be of a great help in detecting these agents.