Colonization factor antigen CS3 (CS3) (CS3)

Colonization factor antigen CS3 (CS3) is a critical surface-expressed virulence factor found in enterotoxigenic Escherichia coli (ETEC), the leading cause of traveler's diarrhea and a major cause of dehydrating diarrhea in children in developing nations (Byrd et al., 2017; Rodas et al., 2011). CS3 belongs to the class of colonization factors (CFs) and specifically functions as a fibrillar adhesin that mediates the attachment of the bacteria to the host's small intestinal epithelium (Chakraborty et al., 2018; DuPont et al., 2016). This adherence is a prerequisite for the subsequent delivery of heat-labile (LT) and heat-stable (ST) enterotoxins, which disrupt electrolyte balance and cause profuse watery diarrhea (Rodas et al., 2023; StatPearls, 2025). Because of its high prevalence among clinical ETEC isolates and its essential role in the early stages of infection, CS3 is a primary target for the development of both whole-cell and subunit vaccines (Akhtar et al., 2024; Cassels et al., 2006). Therapeutic strategies, such as the ETVAX and MecVax vaccine candidates, aim to induce mucosal IgA and systemic IgG antibodies that neutralize CS3, thereby preventing bacterial colonization and the onset of disease (Army Budget, 2000; Byrd et al., 2006).

Other names

Coli surface antigen 3CS3 fimbriaeCS3 piliCFA/II component CS3

Inhibition of bacterial adhesion to host intestinal cells; induction of mucosal IgA and systemic IgG antibodies to prevent colonization.