Creutzfeldt-Jakob SyndromeEncephalopathy, Bovine SpongiformPrionsPrion DiseasesPrPSc ProteinsMeat ProductsAppendixCattleGreat BritainSerial PassageBlood Component TransfusionBrainBlood TransfusionPrPC ProteinsScrapiePalatine TonsilDisease SusceptibilitySheepDisease OutbreaksImmunohistochemistryDisease Models, AnimalIncidenceMice, TransgenicModels, BiologicalSensitivity and Specificity