Enterotoxigenic Escherichia coli heat-labile enterotoxin B subunit (LTB)

Enterotoxigenic Escherichia coli (ETEC) heat-labile enterotoxin (LT) is a primary virulence factor and a major cause of secretory diarrhea in travelers and children in developing countries (UniProt P01556). The toxin is an AB5-type protein complex consisting of a single enzymatic A subunit (LTA) and a pentameric B subunit (LTB) (PubMed: 15505115). LTB is responsible for the high-affinity binding of the toxin to GM1 ganglioside receptors on the surface of intestinal epithelial cells, which triggers the internalization of the A subunit (PubMed: 10455110). Once inside, the A subunit increases intracellular cyclic AMP levels, leading to massive fluid and electrolyte secretion. Because LTB is non-toxic and highly immunogenic, it serves as a critical target for vaccine development, where it induces neutralizing antibodies against specific epitopes that prevent toxin attachment to host cells (PubMed: 29158430). Additionally, LTB is frequently utilized as a potent mucosal adjuvant in experimental immunology to enhance the response to other antigens (PubMed: 11544347).

Other names

Heat-labile enterotoxin B subunitLT-BE. coli heat-labile toxin B subunitLT subunit BEltBHeat-labile enterotoxin subunit B

LTB-targeted interventions primarily work by inducing neutralizing antibodies (IgA and IgG) that bind to specific epitopes on the B subunit, thereby sterically hindering the interaction between the toxin and the host GM1 ganglioside receptor (PubMed: 29158430). This blockade prevents the toxin from entering the enterocyte and initiating the signaling cascade that leads to diarrhea. Additionally, LTB can be used as a carrier or adjuvant to enhance the delivery and immunogenicity of other antigens via its high affinity for mucosal surfaces (PubMed: 11544347).