Enterotoxigenic Escherichia coli colonization surface antigen 5 (CS5) (CS5)

Enterotoxigenic Escherichia coli (ETEC) colonization surface antigen 5 (CS5) is a critical fimbrial adhesin that facilitates the attachment of ETEC to the human intestinal mucosa [1]. As a member of the colonization factor (CF) family, CS5 is frequently associated with ETEC strains causing moderate-to-severe diarrhea in infants in endemic regions and travelers [2]. The protein complex typically consists of major (CsaB) and minor (CsaC) subunits that form thin, flexible fimbriae on the bacterial surface [3]. Because bacterial colonization is a prerequisite for the delivery of heat-labile (LT) and heat-stable (ST) enterotoxins, CS5 serves as a high-priority target for vaccine development [4]. Current therapeutic strategies focus on oral inactivated whole-cell vaccines, such as ETVAX, which are designed to elicit protective secretory IgA responses in the gut to prevent bacterial adhesion [2, 5]. By blocking the initial step of infection, these interventions aim to reduce the global burden of ETEC-mediated diarrheal disease [4].

Other names

Colonization surface antigen 5CS5 fimbriaeCFA/IV component CS5CsaB major subunitETEC CS5

Vaccine-induced production of mucosal secretory IgA (sIgA) and systemic IgG antibodies that bind to CS5, sterically hindering bacterial attachment to intestinal enterocytes and neutralizing colonization [2, 5].