Both cholera toxin-induced adenylate cyclase activation and cholera toxin biological activity are inhibited by antibodies against related synthetic peptides.

The immune response against six synthetic peptides corresponding to various segments of the B subunit of cholera toxin was evaluated. Conjugates in which the peptides were covalently linked to tetanus toxoid served for immunization of rabbits. As previously reported, four of these conjugates elicited antibodies cross-reactive with intact cholera toxin. We report here that antisera against two of these synthetic peptides inhibit the entire spectrum of activities of the intact cholera toxin. This is manifested both on the biochemical level (adenylate cyclase induction) and on the biological effect (intestinal fluid secretion). These results indicate that these peptides may serve as suitable candidates for preparation of a synthetic anticholera vaccine.