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.