BIOLOGICAL RELATIONSHIP BETWEEN F18AB AND F18AC FIMBRIAE OF ENTEROTOXIGENIC AND VEROTOXIGENIC ESCHERICHIA-COLI FROM WEANED PIGS WITH EDEMA DISEASE OR DIARRHEA

Comparative fimbrial expression and adhesion studies were made on ente rotoxigenic and verotoxigenic E. coil (ETEC and VTEC) strains isolated from cases of porcine postweaning diarrhoea or oedema disease. F107(F 18ab) fimbriae-monitored by polyclonal and monoclonal antibodies and b y electron microscopy-were poorly expressed on most VTEC strains. In c ontrast, 2134P(F18ac) fimbriae were more readily detected on most ETEC strains. The F18ac strains adhered in vivo to ligated intestinal loop s in weaned pigs while the F18ab strains did not adhere or adhered wea kly. Similarly, the F18ac strains adhered to isolated intestinal brush borders in weaned pigs but the F18ab strains (except for the F107 ref erence E. coli) did not adhere or adhered weakly in vitro. Neither the F18ab nov F18ac strains adhered to brush borders from newborn pigs. I n vitro adhesion of F18ab and F18ac strains was mannose resistant and receptors for F18 seemed to differ from receptors for K88(F4). It is c oncluded that the antigenic variants of F18 fimbriae (F18ab and F18ac) are biologically distinct. F18ab fimbriae are expressed poorly both i n vitro and in vivo and are frequently linked with the production of S LT-IIv and serogroup O139, while F18ac are more efficiently expressed in vitro and in vivo and most often are linked with enterotoxin (STa, STb) production, and serogroups O141, O157. (C) 1997 Academic Press Li mited