A chimeric protein vaccine composed of the cholera toxin B subunit fused to proinsulin (CTB-INS) was shown to suppress type 1 diabetes onset in NOD mice and upregulate biosynthesis of the tryptophan catabolic enzyme indoleamine 2, 3-dioxygenase (IDO1) in human dendritic cells (DCs).
To optimize the induction of tolerance, we have shown that feeding insulin conjugated to cholera toxin B-subunit (CTB), a potent mucosal adjuvant, reduced by 5,000 the amounts of antigen necessary for delaying diabetes onset in NOD mice.