[Immunogenic properties of foot-and-mouth vaccines]

Studied were the immunity effect and duration with cattle at different age vaccinated with monovalent, bivalent, and trivalent F. M. D. vaccines. It was found that the various F. M. D. vaccines bring about the building up of immunity varying in terms of effectiveness. Calves vaccinated with a single dose of the vaccine obtained but weak immunity of short duration. However, their immunization with a double dose of the vaccine prevented the outbreak of a homologous infection in up to 80 per cent of the animals. Revaccination was shown to confer a stable and lasting immunity. It was demonstrated that the various types of F. M. D. viruses participating in the F. M. D. vaccines differed in immunogenicity. The latter was better with the viruses of the A type as against that possessed by the remaining viruses. Discussed is the importance of the regular prophylactic immunizations of cattle in the control of the foot-and-mouth disease infection.