Cholera toxin (CTX)

Cholera toxin (CTX) is a potent AB5-type enterotoxin produced by the Gram-negative bacterium Vibrio cholerae, serving as the primary virulence factor responsible for the severe watery diarrhea and rapid dehydration characteristic of cholera infections. The toxin’s architecture comprises a catalytic A-subunit (CTA) and a pentameric B-subunit (CTB), which facilitates high-affinity binding to GM1 ganglioside receptors on the surface of host intestinal epithelial cells. Following internalization and retrograde transport to the endoplasmic reticulum, the catalytic A-subunit is released into the cytosol where it performs ADP-ribosylation of the Gs alpha subunit of heterotrimeric G proteins. This covalent modification leads to the constitutive activation of adenylate cyclase and a dramatic increase in intracellular cyclic AMP (cAMP), triggering the opening of CFTR chloride channels and massive osmotic water loss into the intestinal lumen. In clinical practice, the toxin is primarily the target of oral cholera vaccines, such as Vaxchora and Dukoral, which induce neutralizing antibodies to prevent toxin binding and activity. Beyond its pathological role, the non-toxic B-subunit is extensively utilized in research as a retrograde neuronal tracer and a potent mucosal adjuvant for co-administered antigens.

Other names

CholeragenCTCTXCholera enterotoxinVibrio cholerae enterotoxin

Neutralization of toxin activity and inhibition of receptor binding through the induction of specific secretory IgA and serum IgG antibodies via oral vaccination with live-attenuated or inactivated whole-cell and subunit components.