Enterotoxigenic Escherichia coli F4 and F18 fimbrial adhesin (ETEC F4/F18 adhesin)

Enterotoxigenic Escherichia coli (ETEC) F4 and F18 fimbrial adhesins are critical virulence factors that facilitate the attachment of bacteria to the intestinal mucosa of neonatal and weaned pigs (Fairbrother et al., 2005). These adhesins are complex protein filaments, where specific subunits like FaeG (for F4) and FedF (for F18) act as lectins, binding to carbohydrate-containing receptors on the host's enterocytes (UniProt P02971; UniProt Q47510). This adherence is a mandatory step for colonization, allowing the bacteria to resist peristalsis and secrete toxins that cause severe diarrhea and edema disease (Fairbrother et al., 2006). The F4 group includes variants F4ab, F4ac, and F4ad, while the F18 group includes F18ab and F18ac, each targeting different host glycan profiles (Verdonck et al., 2004). Because these proteins are exposed on the bacterial surface and essential for infection, they are the primary antigens in veterinary vaccines, such as Coliprotec F4/F18, which induce protective mucosal immunity (EMA, 2023). Additionally, they are targets for passive immunization using oral antibodies and experimental anti-adhesion therapies that aim to block the initial docking phase of infection (Moon et al., 1999).

Other names

Enterotoxigenic Escherichia coli F4ac/F4ab/F4ad and F18ac/F18ab fimbrial adhesinsK88 fimbriaeF107 fimbriaeFaeGFedFF4 fimbriaeF18 fimbriaeETEC pili

Prevention of bacterial attachment to host enterocytes through immunological neutralization or competitive inhibition.