Prions: Novel Infectious Pathogens

Abstract

Publisher Summary This chapter discusses the properties of the scrapie prion and its relationship to the infectious agents causing other apparently similar diseases. Six diseases are probably caused by prions, including scrapie, transmissible mink encephalopathy (TME), chronic wasting disease (CWD), kuru, Creutzfeldt–Jakob disease, and CJD, and Gerstmann–Straussler syndrome (GSS). Scrapie is a disease of sheep and goats. It is a neurological disorder characterized by pruritus, incoordination, and ataxia of gait. The disease is progressive and invariably fatal, as are all other prion diseases. A prolonged incubation period precedes the onset of clinical illness. The pathology of scrapie is confined to the central nervous system (CNS). Many countries have scrapie surveillance programs. Because sheep with scrapie cannot be treated, they are destroyed. The purification of the scrapie agent has been crucial for the studies defining the properties of the infectious particle. Several different purification procedures have been reported. One involved the copurification of the scrapie agent and microsomes. Another involved the isolation of a “membrane-free” fraction after prolonged ultracentrifugation. Multiple studies have shown that the scrapie agent in crude preparations is resistant to nuclease digestion and to UV irradiation.