Further characterisation of a monoclonal antibody reactive with Escherichia coli O157:H7.

Monoclonal antibody (MAb) 4E8C12 has been previously reported to recognise low mol. wt proteins from enterohaemorrhagic Escherichia coli (EHEC) serotypes O157:H7 and O26:H11. Crude lipopolysaccharide (LPS) preparations from proteinase K-digested bacterial suspensions reacted in Western blots with MAb 4E8C12, as did highly purified LPS from O157:H7 strains. The material recognised by this antibody was, therefore, LPS. The LPS epitope was identified by a whole-cell ELISA in several EHEC, verotoxin producing E. coli (VTEC) and verotoxin-negative strains in addition to E. coli serotypes O157:H7 and O26:H11. Acriflavine and bile salts enhanced the production or availability of the epitope at the cell surface and in culture supernates. These data indicate that the presence of the epitope did not correlate with the virulence of these organisms.