Enterotoxigenic Escherichia coli colonization surface antigen 6 (CS6) (CS6)

Enterotoxigenic Escherichia coli (ETEC) colonization surface antigen 6 (CS6) is a major non-fimbrial adhesin and a critical virulence factor involved in the pathogenesis of bacterial diarrhea (Nicklasson et al., 2008). It is one of the most frequently identified colonization factors (CFs) in ETEC strains isolated from patients with traveler's diarrhea and young children in endemic regions (Qadri et al., 2005). CS6 is a heteropolymeric protein complex consisting of two structural subunits, CssA and CssB, which are assembled on the bacterial surface via a chaperone-usher pathway (Wolf et al., 1997). Its primary biological function is to mediate the attachment of ETEC to human intestinal epithelial cells, facilitating colonization of the small intestine (Tobias et al., 2011). As a key target for prophylactic interventions, CS6 is included in several vaccine candidates, such as the oral inactivated vaccine ETVAX, which induces protective secretory IgA antibodies to block bacterial adhesion (Lundgren et al., 2014). Therapeutic strategies focusing on CS6 aim to prevent the initial stage of infection, thereby neutralizing the bacteria's ability to deliver enterotoxins that cause fluid secretion and diarrhea.

Other names

Colonization surface antigen 6CS6 adhesinCssA/CssB complexETEC CS6Colonization factor CS6

The primary mechanism of action for drugs and vaccines targeting CS6 involves the induction or administration of antibodies, specifically secretory IgA, that bind to the CssA and CssB subunits of the CS6 complex. This binding sterically hinders the adhesin's ability to interact with host cell receptors on the intestinal epithelium, thereby preventing bacterial colonization and the subsequent delivery of enterotoxins (Lundgren et al., 2014; Tobias et al., 2011).