Revaccination response of cattle as a function of the 140S foot and mouth disease antigen dose.

Fifty adult cattle were subdivided in 2 equal groups and inoculated with foot and mouth disease vaccines containing either 5 micrograms or 0.01 microgram of O1BFS 1860 140S antigen per 3 ml dose. Four months later they were subdivided into groups of 5 and injected with vaccines containing concentrations of the 140S antigen ranging from 54 micrograms to 7 ng per 3 ml dose. Bleedings were carried out periodically and the serum neutralizing antibody titres showed that the revaccination responses were influenced by the dose of 140S antigen in both the primary and secondary vaccinations. A linear log relationship was demonstrated between the anamnestic serum antibody log response and the dose of antigen in the secondary vaccines.