Engineering antibody fragments for use in an assay to capture Escherichia coli O157:H7

Abstract

Escherichia coli O157:H7 is an emerging cause of foodborne illness with the occurrence of an estimated 20,000 illnesses and 250 deaths each year in the United States. Human illness associated with E.coli O157:H7, including bloody diarrhea, hemolytic uremic syndrome (HUS) and renal disease, can have serious implications. E.coli O157:H7 infections in humans follows the ingestion of contaminated food. The food contamination is usually associated with animals, mainly cattle. Many cattle become infected early in life when they are exposed to an environment that is contaminated by other animals shedding the organisms in their feces. Toward the goal of developing a biosensor to capture E.coli O157:H7, I have developed a single chain of variable fragment (scFv) molecules from hybridoma clones that produce immunoglobulins specific for the LPS and flagella antigen of E.coli O157:H7 using phage display technology. The soluble scFvs were characterized for specificity by ELISA, and by inhibition of agglutination of the bacteria by polyclonal antiserum. Furthermore, the functionality of the scFv was tested by an immunocapture of the bacteria. The result demonstrated that the scFv maintain the specificity for the anti-O157 and anti-H7 monoclonal antibodies and can be used for capturing E. coli O157:H7.