Diseases, Conditions, Syndromes

Prion diseases: New clues in the structure of prion proteins

Prion diseases are a group of rapidly progressive, fatal and infectious neurodegenerative disorders affecting both humans and animals. Bovine spongiform encephalopathy (BSE) or "mad cow" disease is one of the most famous ...

Diseases, Conditions, Syndromes

Naturally occurring antibodies against prion proteins found in humans

Antibodies targeting the normal PrP version of the prion protein have been found in humans selected at random with no history of any associated transmissible spongiform encephalopathies. The significance is that prion proteins ...

Medical research

First all-human mouse model of inherited prion disease

Human prion diseases include Creutzfeldt-Jakob disease (CJD) and Gerstmann-Sträussler-Scheinker disease (GSS). A new study in the open-access journal PLOS Biology reports a significant advance in the development of mouse ...

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Prion

A prion (pronounced /ˈpriː.ɒn/ ( listen)) is an infectious agent that is composed of protein. To date, all such agents that have been discovered propagate by transmitting a mis-folded protein state; the protein does not itself self-replicate and the process is dependent on the presence of the polypeptide in the host organism. The mis-folded form of the prion protein has been implicated in a number of diseases in a variety of mammals, including bovine spongiform encephalopathy (BSE, also known as "mad cow disease") in cattle and Creutzfeldt-Jakob disease (CJD) in humans. All known prion diseases affect the structure of the brain or other neural tissue, and all are currently untreatable and are always fatal. In general usage, prion refers to the theoretical unit of infection. In scientific notation, PrPC refers to the endogenous form of prion protein (PrP), which is found in a multitude of tissues, while PrPSC refers to the misfolded form of PrP, that is responsible for the formation of amyloid plaques that lead to neurodegeneration.

Prions are hypothesized to infect and propagate by refolding abnormally into a structure which is able to convert normal molecules of the protein into the abnormally structured form. All known prions induce the formation of an amyloid fold, in which the protein polymerises into an aggregate consisting of tightly packed beta sheets. This altered structure is extremely stable and accumulates in infected tissue, causing tissue damage and cell death. This stability means that prions are resistant to denaturation by chemical and physical agents, making disposal and containment of these particles difficult.

Proteins showing prion-type behavior are also found in some fungi and this has been important in helping to understand mammalian prions. However, fungal prions do not appear to cause disease in their hosts and may even confer an evolutionary advantage through a form of protein-based inheritance.

The word prion is a compound word derived from the initial letters of the words proteinaceous and infectious, with -on added by analogy to the word virion.

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