DESIGNATIONS F18AB AND F18AC FOR THE RELATED FIMBRIAL TYPE-F107, TYPE-2134P AND TYPE-8813 OF ESCHERICHIA-COLI ISOLATED FROM PORCINE POSTWEANING DIARRHEA AND FROM EDEMA DISEASE

The relatedness of the fimbriae produced by eight E. coli strains incl uding type strains with F107 fimbriae, 2134P pill and colonization fac tor 8813 (preliminary F18), was examined. These strains had been isola ted principally from pigs which were affected with postweaning diarrho ea or with oedema disease. The fimbriae were analyzed by means of elec tron microscopy, slide agglutination, immunofluorescence, immunogold l abelling, immune-diffusion, immunoelectrophoresis and western blot, mo lecular genetic techniques, and in vitro adhesion. The fimbriae of all the strains were long flexible filaments with a diameter not larger t han 4.6 nm showing a zig-zag pattern. Results obtained by the serologi cal techniques confirmed that the fimbriae possessed a common antigeni c determinant designated 'a' in addition to a variant-specific determi nant designated 'b' or 'c'. Immunoelectron microscopy demonstrated tha t the determinants 'a' and 'b' or 'a' and 'c' were localized along the same fimbrium. In immunoelectrophoresis, fimbrial extracts of selecte d strains yielded a single precipitation line towards the cathode. One single major subunit of approximately 15 kDa was recognised in wester n blots by antisera against the common antigenic determinant and the v ariant specific determinants, All strains possessed sequences related to gene fedA, coding for the major subunit of fimbriae F107, Two types of fedA-related subunit genes were differentiated, corresponding to t he 'ab' and 'ac' types of fimbriae as defined by serological methods. The results demonstrated that F107 fimbriae, 2134P pill and colonizati on factor 8813 are related, and that two serological variants can be d istinguished. We propose designations F19ab (for F107). and F18ac (for 2134P and 8813) in analogy to the nomenclature of F4 fimbriae.