An Enzymatically Active A Domain Is Required for Cholera-Like Enterotoxins To Induce a Long-Lived Blockade on the Induction of Oral Tolerance: New Method for Screening Mucosal Adjuvants

The cholera-like enterotoxins (CLETS), cholera toxin (CT) and Escherichia coli heat-labile toxin (LT), are powerful mucosal adjuvants. Here we show that these toxins also induce a long-lived blockade (of at least 6 months) on the induction of oral tolerance when they are coadministered with the antigen ovalbumin. Strikingly, only enzymatically active CLETS induced this blockade on the induction of oral tolerance. In this regard, the...