PRIONS

Abnormal proteins that turn your brain into Swiss cheese - what are these fascinating and terrifying infectious agents?

By: Umaama Hussain

Prions are an abnormal form of a normally harmless protein. The term was coined in 1982 by Stanley B. Prusiner, and is derived from protein and infection, hence prion, and is short for "proteinaceous infectious particle".

Prions form one of the most intriguing and terrifying fields of biology today. They are the mysterious and infectious culprit of many severe neurodegenerative diseases, and infection is always fatal.

Prions are not fully living organisms like bacteria or parasites and are said to be between the border of living and non-living in terms of classification. As they aren’t really living, prions cannot be killed.

Prions persist in all kinds of environments and can remain contagious for years – and normal sterilization techniques used in hospitals and labs are survivable to them.

Prion proteins (PrP) are normal proteins found on the surface of many cells throughout the body – including the brain. Proteins consist of chains, and when they are created these chains are folded into distinct shapes which allow them to carry out specified functions. The normal structure of PrP is well defined. However, had a chain been misfolded they would take on an abnormal shape, functioning irregularly and even going to the wrong part of a cell.

This is where the issue arises. Infectious PrP has a different, abnormal structure. When this misfolded version of PrP infects the body, it can bind with normal PrP, inducing the protein to fold incorrectly in vitro into less well-defined, and dangerous forms.

This creates a chain reaction and deforms other proteins present in the brain, triggering normal healthy proteins in the brain to fold abnormally – making the brain holier than Swiss cheese (prions create literal holes in the brain).

Additionally, the infectious version of PrP is resistant to proteases, which is the enzyme that breaks proteins down, and so the particles cannot be naturally broken down within the body. This abnormal accumulation of misfolded PrP in the brain causes severe brain damage and results in memory impairment, personality changes, and motor difficulties.

Prions are a relatively new discovery in the field of biology and the overall knowledge on the topic is still full of holes. Though there have been new advancements in knowledge of the method of converting normal PrP into the infectious kind, there is still much to learn on how prions work on a basic level.

Biologists are also working on methods of preventing the accumulation of prions in the environment and thus causing disease.