Saturday 21 September 2013

What Are Prions?

What Are Prions?

Tim Sandle
By Tim Sandle, Ph.D, M.A., BSc (Hons), CBiol, MSBiol., MIScT
A prion is short-hand for proteinaceous infectious particle. Prions are infectious proteins thought to cause disease as viruses do (prions are misfolded, misshapen, proteins). The key difference between a prion and a virus is that prions lack the DNA or RNA that forms the command structure of a virus. Prions have been implicated with a number of diseases, including scrapie, kuru (once called laughing sickness), Creutzfeldt-Jakob disease, and in Bovine Spongiform Encephalopathy (BSE) (the so-termed Mad Cow Disease). Mad-cow disease involves prions which have been passed between cattle by eating feed containing (or contaminated with) brain matter from infected animals, and can then be passed on to humans who eat the similarly contaminated meat of infected cattle. There was an outbreak of this disease in British cattle in the 1980s.
The prion proteins contradict a central tenet of molecular biology: that genes affect proteins, but proteins do not affect DNA. To date, any known disease transmitted by prion is untreatable. Prions attack the nervous system, particularly the brain. Once in an animal's brain cells, proteins near the prions apparently begin to deform and refold themselves to match the defective prion. In sheep, scrapie-infected animals stagger and die as their brains disintegrate. With BSE, humans suffer a hideously similar fate.

Posted by Tim Sandle

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