Colonization factor antigen 6 (CS6) (CS6)

Colonization factor antigen 6 (CS6) is a major non-fimbrial surface adhesin expressed by enterotoxigenic Escherichia coli (ETEC), a primary cause of bacterial diarrhea in children in low-income countries and international travelers (Wolf, 1997, Clinical Microbiology Reviews). The CS6 complex is a heteropolymeric structure composed of two structural subunits, CssA and CssB, which are assembled on the bacterial surface via a specialized chaperone-usher pathway (UniProt P0CK95, P0CK96). Its primary biological role is to mediate the attachment of ETEC to the human intestinal mucosa, a prerequisite for the delivery of heat-labile and heat-stable toxins that induce fluid secretion. Due to its high global prevalence in clinical ETEC isolates, CS6 is a critical component of several oral vaccine candidates, such as ETVAX (Lundgren et al., 2014, Vaccine). These vaccines aim to elicit a robust mucosal immune response, specifically secretory IgA, to neutralize the adhesin and prevent the initial stages of infection.

Other names

CS6 colonization factorCFA/VICssA-CssB complexCS6 adhesin

Induction of mucosal secretory IgA antibodies that bind to the CS6 surface complex, sterically hindering bacterial attachment to the intestinal epithelium and preventing colonization (Svennerholm, 2011, Expert Review of Vaccines).