The word prion is derived from the term "proteinaceous infectious particle".[6][7] The hypothesized role of a protein as an infectious agent stands in contrast to all other known infectious agents such as viroids, viruses, bacteria, fungi, and parasites, all of which contain nucleic acids (DNA, RNA, or both).
All known prion diseases in mammals affect the structure of the brain or other neural tissue; all are progressive, have no known effective treatment, and are always fatal.[9] All mammalian prion diseases were believed to be caused by PrP, until 2015, when a prion form of alpha-synuclein was hypothesized to cause multiple system atrophy (MSA).[10]
Prions are a type of intrinsically disordered protein, which continuously change their conformation unless they are bound to a specific partner such as another protein. With a prion, two protein chains are stabilized if one binds to another in the same conformation. The probability of this happening is low, but once it does, the combination of the two is very stable. Then more units can get added, making a sort of "fibril".[11] Prions form abnormal aggregates of proteins called amyloids, which accumulate in infected tissue and are associated with tissue damage and cell death.[12] Amyloids are also associated with several other neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease.[13][14]
Prion aggregates are stable, and this structural stability means that prions are resistant to denaturation by chemical and physical agents: they cannot be destroyed by ordinary disinfection or cooking. This makes disposal and containment of these particles difficult, and the risk of iatrogenic spread through medical instruments a growing concern.
^"Prion diseases". United States Centers for Disease Control and Prevention. May 3, 2019. Archived from the original on May 18, 2020. Retrieved September 8, 2017.
^Olanow CW, Brundin P (January 2013). "Parkinson's disease and alpha synuclein: is Parkinson's disease a prion-like disorder?". Movement Disorders. 28 (1): 31–40. doi:10.1002/mds.25373. PMID23390095. S2CID38287298.
^Goedert M (August 2015). "NEURODEGENERATION. Alzheimer's and Parkinson's diseases: The prion concept in relation to assembled Aβ, tau, and α-synuclein". Science. 349 (6248): 1255555. doi:10.1126/science.1255555. PMID26250687. S2CID206558562.