Submitted to: Microbial Pathogenesis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/1996
Publication Date: N/A
Citation: N/A Interpretive Summary: Diarrhea in weaned pigs is of major economic importance to the swine industry. Bacteria called Escherichia coli produce toxins that cause diarrhea in weaned pigs. In order to cause disease, these bacteria use structures called fimbriae to bind to the surface of the small intestine. Vaccines directed against fimbriae can prevent bacterial binding and disease. Fimbriae called 2134P facilitate binding by some of the E. coli that cause diarrhea in weaned pigs. 2134P fimbriae are very similar to F107 fimbriae associated with E. coli that produce different toxins and cause edema disease, another disease in weaned pigs. This study describes important differences in how 2134P and F107 fimbriae are identified and shows that 2134P-producing E. coli bind better to pig intestinal cells than do F107-producing E. coli. Recognition of these differences will facilitate development of diagnostic methods and vaccines to prevent economic losses due to diarrhea and edema disease in postweaning pigs. The beneficiaries of this research will be the pork producers and the consumers.
Technical Abstract: Comparative adhesion and antigen expression studies were made on enterotoxigenic (ETEC) and verotoxigenic E. coli (ETEC and VTEC) strains isolated from cases of porcine postweaning diarrhea or oedema disease. F107(F18ab) fimbria - monitored by electron microscopy, by polyclonal and monoclonal antibodies - were detected on VTEC strains and were less expressed than 2134P(18ac) fimbriae that were detected mostly on ETEC strains. F18 genes - monitored by PCR - were detectable in all strains. In vivo adhesion - tested in ligated ileal loops of weaned pigs - was only demonstrated for ETEC strains (F-18ac+) while VTEC strains (F18ab+) did not adhere or adhered weakly. In vitro adhesion was demonstrated to ileal brush borders of weaned pigs for the ETEC strains but it was absent or weak for the VTEC strains except for the F107 reference E. coli. Neither ETEC strains nor F107 reference VTEC strain adhered to brush borders of newborn pigs in vitro. It is concluded that antigenic variants of F18 fimbriae F107(F18ab) and 2134P(F18ac) are biologically distinct: F18ab fimbriae being less expressed in vitro and in vivo and linked with the production of SLT-IIv, while F18ac is more expressed in vitro and in vivo and most often linked with enterotoxin (STa, STb) production. Receptors for K88(F4) and F18 seemed to be different.