CHARACTERIZATION OF F-18 FIMBRIAL GENES FEDE AND FEDF INVOLVED IN ADHESION AND LENGTH OF ENTEROTOXEMIC ESCHERICHIA-COLI STRAIN-107 86/

Infection of susceptible weaned pigs with oedema disease strains of E. coli is associated with bacterial adhesion to the small intestine. F1 8 fimbria (previously named F107) was the first colonisation factor de scribed on oedema disease strains, and its genetic determinant was clo ned. In the present study, genes fedE and fedF were positioned in the F18 gene cluster, downstream of the major structural subunit gene fedA . Two fedE and two fedF mutants were identified that had lost their ca pacity to adhere to isolated porcine villi. Moreover, these mutants pr oduced significantly longer fimbriae. In vitro adhesion tests, electro n microscopy study, transcomplementation tests, and nucleotide sequenc e analysis indicated that proteins FedE and FedF are F18 minor subunit s essential for fimbrial adhesion and effecting fimbrial length. (C) 1 996 Academic Press Limited