Colonization factor antigen I and coli surface antigens 1–6 (CFA/I, CS1–CS6)

Colonization factor antigen I (CFA/I) and the coli surface (CS) antigens CS1, CS2, CS3, CS4, CS5, and CS6 are the primary fimbrial and fibrillar adhesins expressed by enterotoxigenic Escherichia coli (ETEC). These surface structures are essential for the pathogenesis of ETEC-mediated diarrhea, as they facilitate the attachment of the bacteria to specific receptors on the human small intestinal epithelium, such as asialo-GM1 and Lewis A glycans. CFA/I, CS1, CS2, and CS4 are members of the class 5 fimbriae family, which are assembled via the chaperone-usher pathway and utilize a minor tip-localized protein to mediate high-affinity binding to host cells. While these four are structurally related, CS3, CS5, and CS6 belong to distinct morphological groups, yet all seven are collectively targeted in vaccine formulations due to their high prevalence in clinical cases. Current therapeutic strategies, including multivalent subunit vaccines like MecVax and whole-cell vaccines like ETVAX, aim to induce neutralizing antibodies that block bacterial adhesion and prevent colonization. By inhibiting this initial step of infection, these interventions provide broad protection against the diverse strains of ETEC that cause significant global morbidity.

Other names

CFA/I-like colonization factor adhesins CS1–CS6ETEC colonization factorsColi surface antigensFimbrial adhesinsCFA/ICS1CS2CS3CS4CS5CS6

Inhibition of bacterial attachment to host intestinal epithelial receptors, thereby preventing colonization.