Loss of CFA/I expression by enteropathogenic E. coli following exposure to antibody

H-10407 (078, H11) an enteropathogenic strain of Escherichia coli carries a fimbriate plasmid-mediated adherence antigen on the cell surface (CFA/I) which facilitates colonization of human small intestine. This shows strong similarities to the K88 antigen of porcine enteropathogenic E. coli. K88 expression may be suppressed by antibody both in vivo and in vitro. Expression of CFA/I, detected by agglutination of human erythrocytes was progressively lost during in vitro culture with antisera containing antibodies specific for CFA/I but, unlike K88, CFA/I was re-expressed during further culture in the absence of antibody. Antibody to CFA/I seemed to exert a switching effect on expression of the adherence antigen.