The Escherichia Coli/Vibrio Cholerae Family Of Enterotoxins

Comparative Analysis of the Mucosal Adjuvanticity of the Type II Heat-Labile Enterotoxins LT-IIa and LT-IIb

“…Serogroup II enterotoxins include E. coli type II HLT initially designated LT-like toxins and later called LT-II enterotoxins (9). Based on immunoreactivity and amino acid sequence homology, two antigenic variants of LT-II, designated LT-IIa and LT-IIb, have been isolated (9)(10)(11)17). Although serogroup I and serogroup II enterotoxins induce similar morphological effects on Y1 adrenal cells and activate adenylate cyclase in cell cultures, both LT-IIa and LT-IIb appear to be more potent than either CT or LT-I in Y1 adrenal cell assays; however, neither LT-IIa nor LT-IIb induces the typical fluid accumulation in ligated ileal loops observed with CT and LT-I (16).…”

Recombinant Antigen-Enterotoxin A2/B Chimeric Mucosal Immunogens Differentially Enhance Antibody Responses and B7-Dependent Costimulation of CD4+T Cells

“…Additional experiments have demonstrated that the up-regulation of various costimulatory molecules on Ag-presenting cells (APCs) by LT-I B or nontoxic derivatives of CT was abrogated when GM1 binding was blocked (34,52). These studies demonstrate that the GM1 binding properties of the type I HLE appear to be necessary for their adjuvant properties.Two types of HLE have been distinguished on the basis of distinct immunoreactivity (22, 37): type I HLE are represented by CT and LT-I (25, 37); type II HLE include E. coli 23). Although type I and type II HLE are structurally homologous and catalyze similar enzymatic reactions, comparison of the predicted amino acid sequences reveals considerable variability between type I and type II enterotoxin B subunits (22,(37)(38)(39).…”

“…Two types of HLE have been distinguished on the basis of distinct immunoreactivity (22,37): type I HLE are represented by CT and LT-I (25,37); type II HLE include E. coli LT-IIa and LT-IIb (16)(17)(18)23). Although type I and type II HLE are structurally homologous and catalyze similar enzymatic reactions, comparison of the predicted amino acid sequences reveals considerable variability between type I and type II enterotoxin B subunits (22,(37)(38)(39).…”

Characterization of hybrid toxins produced in Escherichia coli by assembly of A and B polypeptides from type I and type II heat-labile enterotoxins

“…The A and B polypeptides of the type II heat-labile enterotoxins were also shown to form holotoxin in vitro without exposure to denaturing conditions, in contrast to the polypeptides of the type I enterotoxins that failed to form holotoxin in vitro under comparable conditions. These findings suggest that type I and type II enterotoxins have conserved structural features that permit their A and B polypeptides to form hybrid holotoxins, although the B polypeptides of the type I and type II enterotoxins have very little amino acid sequence homology.The heat-labile enterotoxins of Escherichia coli and Vibrio cholerae constitute a family of proteins that are related in structure and function (22,33). They are classified into two serogroups (9,21,(37)(38)(39).…”

“…The heat-labile enterotoxins of Escherichia coli and Vibrio cholerae constitute a family of proteins that are related in structure and function (22,33). They are classified into two serogroups (9,21,(37)(38)(39).…”