Laboratory assay methods for bovine tuberculin PPD (report of the Expert Group on Veterinary Sera and Vaccines of the European Pharmacopoeia Commission).
It had been found that preparations of bovine tuberculin PPD that appeared to be similar in potency when assayed in guinea-pigs sensitized with killed tubercle bacilli could differ markedly in potency when assayed in cattle. In an attempt to define a laboratory assay method that would reflect accurately the performance of bovine tuberculin PPD in cattle, the European Pharmacopoeia Group of Experts on Veterinary Sera and Vaccines carried out a collaborative study of various methods of sensitization. Seven laboratories in 6 countries participated. The only method of sensitization that gave results corresponding to those obtained in cattle was that using living, virulent, bovine, tubercle bacilli. The Group concluded that it was essential to use this method in laboratory assays of bovine tuberculin PPD.