Prion

From ArticleWorld

Prion is a shortened term to refer to proteinaceous infectious particles. These are unique types of infectious agents that are made up of only protein. They are abnormal forms of a host protein which convert normal proteins into abnormal structures. They are known to be the cause of some diseases classified as transmissible spongiform encephalopathies (TSEs). These disease affect brian tissue and are fatal.

Prion replication

It is believed that prion particles replicate in the same method as a virus. This involves the synthesis of a polypeptide without the nucleic acid templates and the alteration of cellular proteins. Polypeptides are chains of amino acids. These are normally synthesized by the use of DNA or RNA templates which are the nucleic acid templates. Replication involves conversion of normal proteins into prions. Converted normal proteins then continue the cycle of recruiting normal proteins and changing them to prions.

Prions in fungi

Some prions are found naturally in fungi and non-mammalian organisms. These as opposed to prions found in mammals may not cause any disease and may indeed be useful. Research into fungal prions have clarified the process of synthesis of prions and shown how protein conversion can occur. It has also provided information on the regions in proteins that promote conversions and on mechanisms that can be used to apply to the conversion of all prions.

Prions and diseases

Prion diseases are termed spongiform encephalopathies. This term is used as it describes the appearance of the brain of an infected individual. The brain has large vacuoles in the cortex and cerebellum. Some examples of this type of disease include:

• Scrapie in sheep
• Transmissible mink encephalopathy or TME in mink
• Chronic wasting disease in elk
• Bovine spongiform encephalopathy in cows
• Creutzfeld-Jacob disease in humans