Prions are types of protein that fold in unusual and complex ways. Some prions are, due to the way they are folded, able to replicate by instructing other proteins to misfold in the same way. The way that a prion replicates is similar to the way that a virus replicates and transmits. Despite the ability to replicate, prions are not classed as living entities. The term prion, which was coined in 1982, is an abbreviation for “proteinaceous infectious particle.”
The first prion to be reported was termed “major prion protein” (abbreviated to PrP.) This prion causes a range of diseases: transmissible spongiform encephalopathies, such as bovine spongiform encephalopathy (BSE), what is called “mad cow disease” by many in the media; scrapie in sheep; and Creutzfeldt-Jakob Disease (CJD), a type of human dementia along with variant Creutzfeldt-Jakob Disease (vCJD). To add to these there are other rare conditions that can affect people like Gerstmann–Sträussler–Scheinker syndrome, Fatal Familial Insomnia and kuru. All of these infectious diseases, which affect the brain, are untreatable and fatal.
To add to the knowledge of prions, a new type has been discovered. The discovery further supports the evidence that prions can cause neurodegenerative diseases.
The discovery came about after researchers were investigating a rare and fatal brain disorder called multiple system atrophy (MSA). Here sections of protein were taken from people with the disease and transferred into mice; the mice went on, after several months, to develop the disease. MSA is associated with the degeneration of nerve cells in specific areas of the brain.
The prion believed to cause MSA is termed alpha-synuclein. It is the first new prion to be discovered in half a century. In a research note, lead scientist Kurt Giles, from UC San Francisco, stated “Now we’ve conclusively shown that a new type of prion causes MSA.”
The research has been published in the journal PNAS, in a paper titled “Evidence for α-synuclein prions causing multiple system atrophy in humans with parkinsonism.”
The good news is that the findings raise the possibility for new approaches to developing treatments for MSA, which currently has no cure.