Brain disease-causing prions can form spontaneously on contact with metal
Monday 26 July 2010
Prions, which cause a range of brain wasting conditions including Creutzfeldt–Jakob disease (CJD), can form spontaneously when healthy brain tissue comes into contact with metal, according to new pioneering research from the Medical Research Council (MRC). This rare phenomenon, uncovered by researchers at the MRC Prion Unit, provides an insight into how prions might develop.
In the course of experiments to develop a very sensitive test to detect prions bound to metal surfaces, MRC scientists found that some metal samples exposed to normal, rather than prion-infected, brain tissue were infected with prions. Rigorous and exhaustive experiments were done to exclude the possibility that the wires had become accidentally contaminated in the laboratory.
Prions are known to pose a risk of contamination of medical instruments as they stick tightly to metal surfaces and resist normal hospital sterilisation methods.
Co-author Professor John Collinge, Director of the MRC Prion Unit, a centre of excellence in prion disease, said:
“It came as a complete surprise that these disease-causing prions emerged, as if from nowhere, in healthy brain tissue when it came in contact with the steel wire. That’s why we ran a number of experiments to see if these findings could be replicated. Although this phenomenon is reproducible, the rarity of CJD suggests it seldom occurs, if at all, in surgical practice. There are a number of reports of an association between surgery and sporadic CJD but these may represent prion contamination of instruments during surgery rather than the phenomenon we report here.”
Co-author Julie Edgeworth, from the MRC Prion Unit, said:
“One theory for our observations is that the metal acts as a catalyst to promote the creation of prions from the normal prion protein present in brain tissue. Another possible explanation is that prions are already present at very low and harmless levels in normal brains and contact with metal concentrates them to allow their detection.”
Prion diseases, also called transmissible spongiform encephalopathies (TSEs), belong to a group of progressive conditions that affect the nervous system in humans and animals and are all fatal conditions. In humans, prion diseases impair brain function, causing memory and personality changes, a decline in intellectual function (dementia), and problems with movement that worsen over time. They include classic Creutzfeldt-Jakob disease (CJD), variant CJD, Gerstmann-Sträussler-Scheinker syndrome (GSS), fatal familial insomnia, (FFI) and kuru. In animals, prions cause scrapie, bovine spongiform encephalopathy (BSE) and chronic wasting disease.
The MRC tackles the major health problems of today by supporting basic science. Through understanding how degenerative diseases behave in the lab, researchers can open up new opportunities for preventative measures and treatments for a range of different diseases.
The paper Spontaneous generation of mammalian prions is published today in the journal Proceedings of the National Academy of Sciences.
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Notes to editors
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