Western blot analysis. Lysates of E. coli DH1 carrying the indicated cosmids, E. coli JM109:pEO40, E. coli O157:H7 strain EDL933, or E. coli JM109:pJCP574 were subjected to SDS-PAGE, electroblotted, and probed with convalescent-phase serum from a patient with HUS caused by an O157:H− STEC strain, as described in the text. The mobilities of protein size markers are also indicated.