Vibrio cholerae vaccines.

Several approaches to the development of a safe and effective vaccine against Vibrio cholerae are currently being pursued. These candidate vaccines include (1) live V. cholerae strains attenuated by recombinant DNA techniques; (2) killed whole V. cholerae organisms plus purified cholera enterotoxin B subunit; and (3) cloned V. cholerae antigens in a Salmonella carrier strain. The first two approaches have been the most extensively studied in clinical trials, and all three types of vaccines are administered orally to maximize the stimulation of mucosal immunity. The live attenuated vaccine CVD103-HgR is inexpensive and was effective after a single dose but caused mild diarrhea in 4% of vaccinees. The killed whole cell plus B subunit vaccine is safe but requires the administration of multiple doses. The strong protective immunity conferred by the disease and the rapid progress recently achieved in vaccine development offer encouragement that a successful vaccine will soon be available.