Scrapie is a fatal, neurodegenerative disease of sheep and goat, which belongs together with Bovine Spongiform Encephalopathy and Creutzfeldt-Jakob disease of humans, to the group of Transmissible Spongiform Encephalopathies. TSEs, or prion diseases, affect the central nervous system of many mammals and are characterized by long, asymptomatic incubation periods. The name of TSE arises from the spongiform changes caused by Prions, acronym of Proteinaceous Infectious Particles, defined by the accumulation of an abnormal form of PrP (referred to as PrPSc) of a host membrane glycoprotein (prion protein or PrP) in the CNS.