Novel Properties and Biology of Scrapie Prions

Abstract

Over the past 40 years, an impressive array of data has been accumulated indicating that many features of scrapie, kuru, Creutzfeldt-Jakob disease (CJD), and Gerstmann-Straussler syndrome (GSS) are not typical of infectious diseases. Furthermore, the past two decades have witnessed the collection of numerous experimental results which argue strongly that the scrapie agent is a novel pathogen. To distinguish the scrapie and CJD agents from viroids and viruses, the term “prion” was introduced (Prusiner 1982). Although scrapie can be transmitted to animals by inoculation with extracts of diseased tissue, whether infection features in the spread of natural scrapie is unclear (Parry 1962, 1983; M’Gowan 1914; Westaway et al. 1989; Hourrigan et al. 1979; Gordon 1966; Dickinson et al. 1965; Dickinson 1976). Some investigators have proposed that natural scrapie is a genetic disease and that its transmissibility is incidental (Parry 1962, 1983) while others have argued vehemently that natural scrapie is an infectious disease (Dickinson et al. 1965; Dickinson 1976).