: any of several protein particles that are abnormal forms of normal cellular proteins, that lack nucleic acid, and that in mammals have been implicated as the cause of prion diseases when accumulated in the mammalian brain
Origin of PRION
proteinaceous + infectious + 2-on
First Known Use: 1982
Medical Definition of PRION
: any of various infectious proteins that are abnormal forms of normal cellular proteins, that proliferate by inducing the normal protein to convert to the abnormal form, and that in mammals include pathogenic forms which arise sporadically, as a result of genetic mutation, or by transmission (as by ingestion of infected tissue) and which upon accumulation in the brain cause a prion disease
Disease-causing agent, discovered by Stanley Prusiner, responsible for various fatal neurodegenerative diseases called transmissible spongiform encephalopathies. An abnormal form of a normally harmless protein found in mammals and birds, the disease-causing prion can enter the brain through infection, or it can arise from a mutation in the gene that encodes the protein. Once present in the brain it causes normal proteins to refold into the abnormal shape. As prion proteins multiply, they accumulate within nerve cells, destroying them and eventually causing brain tissue to become riddled with holes. Diseases caused by prions include Creutzfeldt-Jakob disease, mad cow disease, and scrapie. Prions are unlike all other known disease-causing organisms in that they appear to lack nucleic acid (DNA or RNA).