Enterotoxigenic Escherichia coli surface antigens and toxins (ETEC antigens and toxins)

Enterotoxigenic Escherichia coli (ETEC) surface antigens and toxins are the primary virulence determinants of ETEC, a leading cause of bacterial diarrhea worldwide, particularly in children in low-income countries and travelers to endemic regions (Fleckenstein et al., 2010, Nature Reviews Microbiology). The surface antigens, primarily colonization factors (CFs) such as CFA/I and various coli surface (CS) proteins, are fimbrial or non-fimbrial proteins that facilitate the attachment of the bacteria to the small intestinal epithelium, which is essential for establishing infection (Qadri et al., 2005, Clinical Microbiology Reviews). Following colonization, ETEC produces heat-labile (LT) and/or heat-stable (ST) enterotoxins. LT is an AB5-type toxin that increases intracellular cAMP, while ST is a small peptide that increases intracellular cGMP, both leading to massive fluid and electrolyte secretion into the intestinal lumen (Svennerholm, 2011, Vaccine). These components are the primary targets for vaccine development, with strategies focusing on inducing neutralizing antibodies against both the CFs to prevent colonization and the toxins to mitigate symptoms (Bourgeois et al., 2016, Journal of Infectious Diseases). Current therapeutic research includes multi-antigen vaccines like ETVAX and monoclonal antibodies designed to block specific adhesion proteins.

Other names

ETEC virulence factorsColonization factor antigens (CFAs)Heat-labile enterotoxin (LT)Heat-stable enterotoxin (ST)Coli surface (CS) antigens

The mechanism of action involves the induction of mucosal and systemic antibodies that neutralize the heat-labile (LT) and heat-stable (ST) enterotoxins and/or inhibit the binding of colonization factors (CFs) to host intestinal receptors, thereby preventing bacterial attachment and subsequent fluid secretion (Fleckenstein et al., 2010; Svennerholm, 2011).