Heat-labile Enterotoxin (HLT)

Heat-labile enterotoxins (HLTs) are potent immunomodulatory proteins produced by bacteria such as *Escherichia coli* and *Vibrio cholerae*. They are AB5-type toxins with an A subunit possessing ADP-ribosyltransferase activity and a pentameric B subunit for cell binding. HLTs, especially the heat-labile enterotoxin from *E. coli* (LT), have been extensively studied for their strong adjuvant properties in mucosal vaccines. Mutant forms like mLT or dmLT are engineered to reduce toxicity while retaining adjuvanticity.

Other names

LTE. coli Heat-labile ToxinCholera-like toxinmLT (mutant LT)dmLT [LT(R192G/L211A)]

HLTs act primarily by increasing intracellular cAMP via activation of adenylate cyclase after binding to ganglioside receptors on host cells. This elevation in cAMP modulates immune responses by enhancing antigen-presenting cell function, promoting B cell differentiation, and inducing Th2 responses.