Prion disease

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A prion disease is a type of proteopathy, or disease of structurally abnormal proteins. In humans, prions are believed to be the cause of Creutzfeldt–Jakob disease (CJD), its variant (vCJD), Gerstmann–Sträussler–Scheinker syndrome (GSS), fatal familial insomnia (FFI), and kuru. It is a type of protein that can trigger normal proteins in the brain to fold abnormally. Prion diseases can affect both humans and animals and are sometimes spread to humans by infected meat products. The most common form of prion disease that affects humans is Creutzfeldt-Jakob disease (CJD). Some researchers believe that the prions are formed when PrP associates with a foreign pathogenic nucleic acid. This is called the virino hypothesis. (Viruses consist of proteins and nucleic acids that are specified by the virus genome.

"When they are healthy, they look like tiny spheres; when they are malignant, they appear as cubes" stated Giuseppe Legname, principal investigator of the Prion Biology Laboratory at the Scuola Internazionale Superiore di Studi Avanzati (SISSA) in Trieste, when describing prion proteins.

Prion Diseases:

The human forms of prion disease are most often the names Creutzfeldt-Jakob disease (CJD), fatal familial insomnia (FFI), Gertsmann-Straussler-Scheinker syndrome (GSS), kuru and variably protease-sensitive prionopathy (VPSPr). Sixteen different variants of prion disease have been reported so far: nine in humans and seven in animals.

• Creutzfeldt-Jakob Disease (CJD)

• Variant Creutzfeldt-Jakob Disease (vCJD)

• Gerstmann-Straussler-Scheinker Syndrome.

• Fatal Familial Insomnia.

• Kuru.

Prions are tiny proteins that, for some reason, fold over in a way that damages healthy brain cells. You can have them for many years before you notice any symptoms. Prion diseases cause dementia, but not Alzheimer's disease. Different genes and proteins are involved in Alzheimer's.

Cooking does not destroy prions, and ingestion of another prion, the agent that causes bovine spongiform encephalopathy (BSE), has been linked to a fatal human neurological disease. Prions are very stable molecules that do not break down easily. Normal sterilization procedures such as cooking, washing and boiling do not destroy them, now proven that a 40% solution of household bleach and water will effectively kill the prions that transmit the disease. Incineration of prion-contaminated material is considered the most effective method of disposal. Combustion at 1,000°C can destroy prion infectivity, however, low infectivity remains after treatment at 600°C.

The only way to confirm a diagnosis of prion disease is through a brain biopsy performed after death. However, a healthcare provider can use your symptoms, medical history, and several tests to help diagnose prion disease. The tests they may use include: Magnetic resonance imaging (MRI).

Once prions infect the body, they cannot be destroyed. As they accumulate, the misshapen proteins somehow trigger neighbor proteins to behave similarly, eventually taking the place of normal proteins and destroying brain cells. Brain-wasting proteins called prions kill neurons by shortening the dendritic spines that the cells use to transmit signals to each other. Prions are infectious and cause neurodegenerative diseases such as scrapie in animals and Creutzfeldt–Jakob disease in humans.

Potential effects include increased formation of an aberrant transmembrane form of PrP, termed CtmPrP, and changes in plasma membrane properties. In addition to direct and indirect toxic effects of PrPSc, a loss of function of PrPC may contribute to neuronal cell death. Interment of bodies in closed caskets does not present a significant risk of environmental contamination and cremated remains can be considered sterile, as the infectious agent does not survive incineration-range temperatures.

Formation and aggregation of misfolded proteins in the central nervous system (CNS) is a key hallmark of several age-related neurodegenerative diseases, including Parkinson's disease (PD), Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS).

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Regards
David Paul
Editorial Team
Journal of Clinical & Experimental Neuroimmunology