Detection of intimin and EspA from pathogenic E. coli with monoclonal scFvs. (A and B) Outer membrane fractions were prepared from pathogenic E. coli serotypes O127:H6 (α intimin, lane 1), O111:NM (β1 intimin, lane 2), O157:H7 (γ1 intimin, lane 3), O86:H34 (β2 intimin, lane 4), a nonpathogen K-12 strain (lane 5), and an O157:H7 intimin (−) mutant DM3 (lane 6) and then resolved on a 10% (wt/vol) SDS-PAGE gel (7.5 μl/lane, Coomassie blue-stained gel shown in panel A). A Western blot of the gel was developed with I4 (panel B, 5 ml of culture supernatant/blot). (C) Whole-cell preparations of E. coli O157:H7 were prepared and resolved on a 12% (wt/vol) SDS-PAGE gel (10 μl/lane). Lane 7 shows Coomassie blue staining, and lane 8 shows a Western blot developed with E1 (affinity-purified scFv from 25 ml of culture). ScFv binding was detected with anti-c myc antibody.