Escherichia coli F18ab fimbrial adhesin (FedF) (F18ab (or FedF))

Escherichia coli F18ab fimbrial adhesin (FedF) is a protein structure (fimbriae) located on the surface of certain pathogenic E. coli that infect pigs, especially causing post-weaning diarrhea and edema disease. These fimbriae facilitate specific binding of the bacterium to receptors on porcine enterocytes through the FedF adhesin subunit, enabling colonization and subsequent disease. The F18ab variant is specifically associated with Shiga toxin-producing E. coli (STEC) and is a primary factor in the organism's ability to cause severe disease. Targeting this antigen has been a focus for vaccine development and diagnostic approaches in livestock health[1][2][5]. The F18 fimbriae consist of a major structural subunit (FedA) and minor subunits, with FedF acting as the critical adhesin for cell attachment[2][5]. F18ab+ E. coli primarily colonize the porcine small intestine, and their adhesion is a prerequisite for toxin delivery and disease manifestation in pigs[2]. Vaccine development efforts focus on eliciting antibodies against F18ab/FedF to impair adhesion and prevent disease[2]. The existence of antigenic variants (F18ab and F18ac) reflects sequence diversity among field isolates, but both bind similar or identical porcine receptors[1][2].

Other names

F18ab fimbriaeF18ab adhesinF18 fimbrial antigenF18ab surface antigenFedF (fimbrial adhesin)F18+

Vaccine strategies target F18ab/FedF to produce antibodies that prevent bacterial adhesion to the porcine intestinal epithelium, thus blocking infection