Heat-labile enterotoxin B subunit (LTB) (LTB)

The Heat-labile enterotoxin B subunit (LTB) is the non-toxic, pentameric binding component of the heat-labile enterotoxin (LT) secreted by Enterotoxigenic Escherichia coli (ETEC) [2, 3]. LTB forms a ring-shaped structure that mediates the attachment of the holotoxin to GM1 ganglioside receptors on the surface of host intestinal epithelial cells [2, 6]. This binding is a prerequisite for the internalization of the catalytic A subunit, which subsequently activates adenylate cyclase, leading to increased intracellular cAMP and the characteristic watery diarrhea associated with ETEC infection [3, 14]. Beyond its role in pathogenesis, LTB is highly immunogenic and possesses potent adjuvant properties, making it a central target for the development of vaccines against traveler's diarrhea and childhood ETEC infections [4, 15]. It is utilized in various vaccine formulations, including the licensed cholera vaccine Dukoral (which provides cross-protection) and candidates like Etvax, to elicit protective mucosal IgA and systemic IgG antibodies that neutralize the toxin's effects [1, 17]. Additionally, LTB is being explored as a carrier protein for other antigens to enhance their immunogenicity in multivalent vaccine strategies [4, 17].

Other names

LT-BHeat-labile enterotoxin subunit BEltBLT-I B subunitETEC LTB

LTB acts as a primary antigen in vaccines to induce neutralizing IgA and IgG antibodies that block the toxin's binding to host GM1 ganglioside receptors, thereby preventing cellular intoxication and diarrhea.