F4 fimbrial adhesin FaeG (FaeG)

F4 fimbrial adhesin FaeG is the major structural and adhesive subunit of the F4 (formerly K88) fimbriae found on enterotoxigenic Escherichia coli (ETEC) (UniProt: P02971). It plays a critical role in the pathogenesis of porcine neonatal and post-weaning diarrhea by mediating the attachment of the bacteria to specific glycoprotein receptors on the brush border of porcine enterocytes (PubMed: 25100769). FaeG is a bifunctional protein that acts as both a building block for the fimbrial filament and a lectin that recognizes carbohydrate moieties on host cells (PubMed: 15103018). Because colonization is a prerequisite for the delivery of enterotoxins, FaeG is a primary target for the development of veterinary vaccines and anti-infective therapies (PubMed: 30254541). Current strategies include the use of live-attenuated oral vaccines, such as Coliprotec, and recombinant subunit vaccines designed to elicit a protective mucosal immune response (EMA: Coliprotec F4). Additionally, research into small-molecule glycomimetics aims to competitively inhibit FaeG-mediated adhesion to prevent infection (PubMed: 22493359).

Other names

K88 fimbrial adhesinMajor subunit FaeGF4 fimbriae major subunitK88 major subunitProtein FaeG

Vaccines targeting FaeG aim to induce mucosal IgA antibodies that bind to the adhesin, thereby sterically hindering the interaction between the bacteria and the host intestinal receptors (PubMed: 30254541). Anti-adhesion drugs or glycomimetics act as competitive inhibitors by mimicking the host cell receptors, binding to the FaeG lectin domain and preventing bacterial colonization (PubMed: 22493359).