The goals of this project are to study the immunomodulatory activities of LT-IIa and LT-IIb. Both toxins are potent mucosal adjuvants which elicit patterns of immune responses distinct from those elicited by cholera toxin. The toxins will be used as molecular tools to investigate the mechanisms that regulate adjuvant activity. We will engineer a new class of recombinant toxins to evaluate as potential mucosal vaccines.