Foot and mouth disease vaccine potency tests in cattle: the interrelationship of antigen dose, serum neutralizing antibody response and protection from challenge.

The use of tests in cattle remains the basis for evaluating the potency of foot and mouth disease (FMD) vaccines intended for use in cattle. To be able to compare different types of potency test it is essential to have a good understanding of how measurable responses in cattle to vaccination relate to one another. In this paper the interrelationships were examined of log antigen dose (V50), serum neutralizing antibody response (SN50), and protection from challenge (probit), following a single-dose primary vaccination. Estimates of the slopes for each of the three regressions were obtained and these, together with values described by other authors, were used to evaluate how well some of the potency tests for FMD vaccines matched up to Recommendations of the Office International des Epizooties made in 1975.