prion

prion /pri·on/ (pri´on) any of several transmissible forms of the core of prion protein that cause a group of neurodegenerative diseases. Prions differ in structure from normal prion protein, lack detectable nucleic acid, and do not elicit an immune response.

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pri·on (prn)

n.

A microscopic protein particle, apparently self-replicating despite the absence of nucleic acid, thought to be the infectious agent that causes Creutzfeld-Jakob disease and certain other neurodegenerative diseases.

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prion

[prī′on]

one of several kinds of proteinaceous particles believed to be responsible for transmissible neurodegenerative diseases, including scrapie in sheep and kuru and Creutzfeldt-Jakob disease in humans. Because prions lack detectable nucleic acid, they are not inactivated by the usual procedures for destroying viruses. They also do not trigger an immune response.

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prion

a small protein which is believed capable of infecting cells and causing itself to be replicated, even though it contains no nucleic acid, i.e. it is believed to induce transcription of the gene that codes for the prion protein. In some way the horizontally acquired prion also alters the folding of the expressed protein and it is the altered protein that polymerizes to form fibrils within neurons and causes the spongiform encephalopathy. Aspects of this prion theory remain controversial. Prions can be detected in tissues by infective bioassay, animal inoculation, or by Western blot or immunochemistry. Prions cause spongiform encephalopathies of humans and animals, such as Creutzfeldt-Jakob disease, kuru, scrapie, transmissible mink encephalopathy, feline spongiform encephalopathy, and bovine spongiform encephalopathy.

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prion

Slow spongiform encephalopathy virus Molecular medicine An unconventional 33–35 kD sialoglycoprotein, the smallest known infective particle and implicated in diseases of man–Creutzfeldt-Jakob disease-CJD, fatal familial insomnia, Gerstmann-Straussler-Scheinker syndrome, kuru, and animals–scrapie of sheep and goats, bovine spongiform encephalopathy, transmissible mink encephalopathy, chronic wasting disease of captive mule, deer, elk. See Creutzfeldt-Jakob disease, Protein-only hypothesis.