An oral B subunit: whole cell vaccine against cholera.

During the last decade there has been a rapid progress in the development of new, much improved vaccines against cholera. These vaccines, which are given orally to stimulate the gut mucosal immune system, are based on either a combination of purified cholera toxin B (binding) subunit and killed cholera vibrios of Inaba and Ogawa serotypes and El Tor and classical biotypes (B subunit-whole cell vaccine, B-WC) or on a live attenuated mutant strain of Vibrio cholerae producing the B subunit (CVD 103-HgR). The safety of the oral B-WC cholera vaccine and the immunogenicity and protective efficacy of this vaccine against both cholera and diarrhoea caused by enterotoxigenic Escherichia coli have been extensively documented, e.g. in a large randomized, placebo-controlled field trial in 90,000 persons living in a cholera endemic area. The potential for inexpensive large-scale manufacturing of the B-WC vaccine has recently been much facilitated by the introduction of recombinant DNA technology for production of the B subunit component. This now gives promise that this vaccine could become a useful, cost-effective tool in future strategies to control cholera both in endemic situations and in relation to acute epidemic outbreaks.