Antigenicity of cholera toxoid in humans.

A cholera toxoid was produced by heating of a purified cholera toxin and treatment of the resulting toxoid procholeragenoid with a formaldehyde solution. When given subcutaneously and intramuscularly to volunteers in doses of 3-100 microng, the toxoid produced no noteworthy side effects, but the injections produced a dose-dependent rise in level of toxin-neutralizing antibodies in serum. Administration of toxoid in combination with whole-cell vaccine induced antitoxin levels that seemed to be higher than those induced by toxoid alone, but statistical analysis revealed a significant difference only between titers after administration of 10 microng of toxoid alone and those after administration of 10 microng of toxoid in combination with whole-cell vaccine.