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.

[Effectiveness and tolerance of the rabies vaccine Lyssavac Berna].

Rabies vaccine derived from human diploid cells (Wyeth, Merieux) and the duck embryo vaccine Lyssavac Berna are prepared from beta-propiolactone-inactivated Pitman-Moore vaccine virus strain. A group of 113 seronegative veterinary students was vaccinated with Lyssavac Berna according to the 4-dose immunization schedule recommended by WHO. Seroconversion was obtained in all test persons.

Preparation of a purified antigenic cholera toxoid.

Purified cholera enterotoxin was prepared by methods described by Finkelstein and Lo Spalluto (1970). This toxin was detoxified by treatment with heat and formaldehyde. Heating cholera toxin at 60 C for 25 min resulted in the formation of a polymer named procholeragenoid by Finkelstein et al.