Small proteinaceous infectious particles which resist inactivation by procedures that modify NUCLEIC ACIDS and contain an abnormal isoform of a cellular protein which is a major and necessary component. The abnormal (scrapie) isoform is PrPSc (PRPSC PROTEINS) and the cellular isoform PrPC (PRPC PROTEINS). The primary amino acid sequence of the two isoforms is identical. Human diseases caused by prions include CREUTZFELDT-JAKOB SYNDROME; GERSTMANN-STRAUSSLER SYNDROME; and INSOMNIA, FATAL FAMILIAL.
ELECTROMAGNETIC RADIATION or particle radiation (high energy ELEMENTARY PARTICLES) capable of directly or indirectly producing IONS in its passage through matter. The wavelengths of ionizing electromagnetic radiation are equal to or smaller than those of short (far) ultraviolet radiation and include gamma and X-rays.