A potency test method for foot and mouth disease vaccine based on the serum neutralizing antibody response produced in cattle.

A method is described for converting a mean serum neutralizing antibody titre after primary vaccination directly into a percentage protection value using a single regression slope. This has advantages over the indirect method in which a potency value is first estimated on the log antigen dose scale before conversion to a percentage protection value, since to do this requires the use of three separate regression slopes. Test designs for the serological method have been formulated that meet the 1975 Recommendations of the Office International des Epizooties, and which possess minimum potency standards at least as high as those of the European Pharmacopoeia's vaccine dose extinction endpoint method.

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.

A clonal selection based timecourse model for antibody responses to killed vaccine, with applications to foot and mouth disease.

Published models for the timecourse of the immune response are reviewed for their applicability to data from animals that have been injected with killed vaccine. Simple models are required so that statistical fitting procedures become straightforward. A class of models that incorporates the concept of clonal selection has been found useful.