Colonization factor antigen CS1 fimbrial adhesin (CS1)

Colonization factor antigen CS1 (CS1) is a critical fimbrial adhesin expressed by Enterotoxigenic Escherichia coli (ETEC), which is a major cause of moderate-to-severe diarrhea in children in low-income countries and the primary cause of traveler's diarrhea (UniProt P0CK95; PubMed: 31604715). CS1 is a member of the CFA/II group of colonization factors and consists primarily of the major subunit CooA, which assembles into a pilus structure that facilitates the attachment of the bacteria to the human intestinal epithelium (PubMed: 25691593). This adhesion is the essential first step in ETEC pathogenesis, allowing the bacteria to colonize the small intestine and deliver heat-labile (LT) and heat-stable (ST) enterotoxins that trigger fluid secretion. Because of its prevalence and role in virulence, CS1 is a key component in several vaccine candidates, most notably the oral inactivated whole-cell vaccine ETVAX, which has shown the ability to induce robust mucosal IgA responses in clinical trials (PubMed: 31604715, 33153445). Therapeutic strategies targeting CS1 focus on neutralizing the adhesin to prevent bacterial docking, thereby blocking the infection cycle before toxin-mediated damage occurs.

Other names

CS1 fimbriaeCooAColonization factor antigen II component CS1ETEC CS1 adhesinMajor fimbrial subunit CooA

Induction of mucosal secretory IgA antibodies that bind to the CS1 fimbriae, preventing bacterial attachment to the intestinal mucosa and subsequent colonization.