Colonization factor antigen I fimbriae (CFA/I)

CFA/I fimbriae are rigid, rod-like surface structures composed mainly of polymerized CfaB subunits and tip-located minor adhesive subunit CfaE[1][2][3][4][6]. They are assembled through the alternate chaperone pathway, with a gene cluster (cfaABCE) directing their production[6]. CFA/I mediates the initial binding of ETEC bacteria to glycosphingolipids and other receptors on the small intestine epithelium, facilitating colonization and subsequent delivery of bacterial toxins that cause watery diarrhea[1][3][6]. The tip protein, CfaE, contains the primary receptor-binding domain[2][4], while CfaB binds a range of glycosphingolipid moieties[3][6]. Antigenic variation in surface-exposed regions is a key bacterial strategy to evade immune recognition[1]. CFA/I is a principal target for vaccine development, as antibodies that recognize its subunits can block ETEC attachment and provide protective immunity[1][4][6].

Other names

CFA/IColonization factor antigen IClass 5 fimbriae (specifically subclass 5a)Cfa fimbriae

Neutralizing/anti-adhesion antibodies block fimbriae-mediated attachment to host cells. Potential vaccine antigens trigger protective immune responses that block colonization.