Anti-cholera response elicited by a completely synthetic antigen with built-in adjuvanticity administered in aqueous...

Some synthetic peptides derived from the B subunit of cholera toxin, conjugated to tetanus toxoid have been shown by us to be efficient when administered in complete Freund's adjuvant (CFA), in induction of anticholera toxin response with neutralizing capacity. When the peptide CTP3, corresponding to residues 50-64 within the sequence of the B subunit, was attached to the hardly immunogenic A-L (multichain poly-DL-alanine) the resulting conjugate did not lead to a significant anti-peptide response even when given in CFA. On the other hand, when CTP3 was coupled to the immunogenic (T,G)-A-L, the resulting CTP3-(T,G)-A-L led, in CFA, to protective anti-cholera antibodies. Moreover, covalent attachment of the synthetic adjuvant N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) to the latter immunogen led to MDP-CTP3-(T,G)-A-L which, when administered in aqueous solution, elicited in rabbits antibodies with neutralizing capacity.