Enterotoxigenic Escherichia coli colonization factor antigen I and related fimbrial antigens (CFA/I)

Enterotoxigenic Escherichia coli (ETEC) colonization factor antigen I (CFA/I) is a major fimbrial adhesin and a primary virulence factor responsible for the attachment of ETEC to the human small intestinal mucosa (nih.gov, 1.1.1). As the archetype of Class 5 fimbriae, CFA/I is composed of thousands of CfaB major structural subunits and a minor tip subunit, CfaE, which mediates specific receptor binding (nih.gov, 1.2.3). This adherence is the critical first step in ETEC pathogenesis, allowing the bacteria to colonize the gut and subsequently release enterotoxins that cause secretory diarrhea (mdpi.com, 1.1.3). Because of its high prevalence in clinical isolates and its essential role in infection, CFA/I and related coli surface (CS) antigens, such as CS1 through CS6, are central targets for the development of vaccines (plos.org, 1.2.1). Current vaccine strategies include oral inactivated whole-cell mixtures like ETVAX and various subunit candidates like MecVax or dscCfaE (plos.org, 1.1.5; mdpi.com, 1.4.1). These therapeutic interventions aim to elicit mucosal antibodies, particularly secretory IgA, that block bacterial colonization and prevent the establishment of disease (nih.gov, 1.4.5). However, the extensive antigenic diversity among the more than 30 identified colonization factors presents a significant challenge for achieving broad, cross-protective immunity (nih.gov, 1.4.4). Research into multiepitope fusion antigens (MEFAs) is ongoing to address this heterogeneity by combining epitopes from multiple fimbrial types into a single immunogen (plos.org, 1.1.5).

Other names

CFA/IColonization factor antigen IColi surface antigensCS antigensETEC fimbriaeETEC piliClass 5 fimbriaeCfaBCfaE

Induction of mucosal antibodies to block bacterial adhesion and colonization of the small intestine.