Enterotoxigenic Escherichia coli antigen and heat-labile enterotoxin (ETEC antigen; Heat-labile enterotoxin (LT))

Enterotoxigenic *Escherichia coli* (ETEC) produces a mixture of antigens, including colonization factor antigens (CFAs/CS) which mediate intestinal attachment, and the heat-labile enterotoxin (LT), a major virulence factor causing diarrhea via cAMP-mediated fluid secretion. LT is an AB5-type toxin composed of an enzymatic A subunit (with ADP-ribosyltransferase activity) and a receptor-binding B subunit pentamer; LT binds GM1 ganglioside receptors on host cells and disrupts ion transport, leading to the characteristic watery diarrhea of ETEC infection[4][5][7]. LT is also a strong mucosal adjuvant and is used in vaccine design, both for its immunogenic properties and as a platform to display additional antigenic epitopes. ETEC antigens, including CFAs and secreted proteins like EtpA, are targets for vaccines preventing colonization. While antibody responses against LT and these antigens protect against disease, there are currently no licensed vaccines, and most therapies are preventative. Safety considerations demand detoxified or engineered non-toxic forms of LT for clinical use, especially in vaccines[1][2][3][4][5][6][7].

Other names

ETEC heat-labile enterotoxinLTETEC antigensETEC CF antigens (Colonization factor antigens)CFA/ICS antigens

Neutralization of enterotoxin activity (antibody-based or vaccine-induced immunity inhibits toxin binding or activity). Prevention of colonization (antibody-based targeting of adhesins/antigens impairs ETEC attachment). Enhanced immune response (LT as adjuvant increases immunogenicity of coadministered antigens).