F4 and F18 fimbriae (F4/F18)

F4 (formerly K88) and F18 fimbriae are specialized proteinaceous surface appendages found on enterotoxigenic Escherichia coli (ETEC) that mediate the attachment of bacteria to the small intestinal mucosa of swine (Fairbrother & Nadeau, 2006). These fimbriae are essential virulence factors because they allow the bacteria to resist peristaltic clearance and colonize the gut, where they subsequently release enterotoxins that cause post-weaning diarrhea and edema disease (Duan et al., 2013). F4 fimbriae exist in three variants (F4ab, F4ac, and F4ad) and bind to various glycoproteins, while F18 fimbriae (variants F18ab and F18ac) target specific carbohydrate structures on the brush border (Verdonck et al., 2004). In veterinary medicine, these fimbriae are the primary targets for oral live vaccines, such as Coliprotec F4/F18, which induce local mucosal immunity to prevent bacterial adhesion (EMA, 2016). Additionally, passive immunization using egg yolk antibodies or specific probiotics is explored to interfere with the binding of these adhesins to host receptors. Understanding the genetic susceptibility of the host, such as polymorphisms in the MUC4 or FUT1 genes, is crucial for managing ETEC infections as these determine the presence of the fimbrial receptors (Jorgensen et al., 2003).

Other names

K88 fimbriaeF107 fimbriaeETEC adhesinsColonization factor F4Colonization factor F18Fimbrial adhesin F4Fimbrial adhesin F18

Inhibition of bacterial attachment to the intestinal mucosa by blocking fimbrial adhesins, thereby preventing colonization and the subsequent delivery of enterotoxins.