Most commercially available enzyme-linked immunosorbent
assays incorporate a polyclonal E. coli O157:H7 antibody instead
of a monoclonal alternative, perhaps because of the ease
and low cost of preparation of the polyclonal antibody, the
inability of the monoclonal antibody to achieve a significant
increase in specificity, and the retention of greater sensitivity
with the polyclonal antibody. Because polyclonal antibodies
have been shown to be more sensitive than monoclonal antibodies,
while retaining specificity, we decided to use a polyclonal
affinity-purified HRP-labeled goat anti-E. coli O157:H7
antibody (KPL). This antibody has been shown to be reactive
to E. coli O157:H7 and specific for the O157 lipopolysaccharide
antigen (Fig. 1).