Enterotoxigenic Escherichia coli colonization factor antigen I fimbria (CFA/I fimbria)

The Enterotoxigenic Escherichia coli colonization factor antigen I fimbria (CFA/I fimbria) is a filamentous, surface-exposed structure on ETEC bacteria assembled mainly from the major subunit CfaB, with a minor tip adhesin subunit, CfaE[1][7]. CFA/I fimbriae mediate the critical first step of ETEC pathogenesis by adhering to specific glycosphingolipid receptors on the small intestinal epithelial cells of human hosts, facilitating colonization[7]. The structure is helical but can unwind under force during host interaction[4][5]. CFA/I fimbriae are the archetype of the class 5 fimbriae group, a major type of ETEC colonization factors, and are assembled by the chaperone-usher pathway[5][6]. These fimbriae are strongly immunogenic and are considered prime targets for vaccine development, as inhibition (via vaccine-induced antibodies or passive immunization) blocks bacterial attachment and prevents disease[8]. Antigenic variation in exposed fimbrial domains enables immune evasion, representing a challenge for long-term vaccine effectiveness[1][2].

Other names

Colonization factor antigen ICFA/I piliCFA/I fimbriaeCFA/I

Inhibition of bacterial adhesion to intestinal epithelial cells (by antibodies or vaccine-induced immunity) prevents colonization and subsequent diarrheal disease[8].