Sheep infected with scrapie and cows infected with BSE have elevated levels of manganese in their blood before clinical symptoms appear, according to new research.
The findings, published in the Journal of Animal Science, also show that scrapie-resistant sheep produce elevated levels of the metal when challenged with the disease.
This suggests that elevated manganese levels in the blood and central nervous system are caused by the animals initial response to the disease.
The findings raise the possibility of using manganese levels in the blood as a potential diagnostic marker for prion infection. At present, only post-mortem examination of the brain tissue gives a certain diagnosis.
Scrapie, Bovine Spongiform Encephalopathy (BSE) and Creutzfeldt-Jakob Disease (CJD) are neurodegenerative diseases that affect the brain and nervous system of sheep, cows and humans respectively.
They are transmitted by mis-formed prion proteins which cause tiny loss of brain cell in different regions of the brain, leading to impairment of brain function, including memory changes, personality changes and problems with movement that worsen over time.
Definite diagnosis of prion disease is currently only possible post-mortem, said Professor David Brown from the University of Bath who led the study with colleagues from the universities of Hull and Edinburgh.
These findings suggest that elevated blood manganese could be used as a robust diagnostic marker for prion infection, even before the onset of apparent clinical disease.
In practice, however, it would be difficult implement a widespread screening programme, given that the mass spectrometry we use to measure levels is expensive and labour intensive.
The research builds on the 2002 discovery that mice infected with scrapie have higher levels of manganese. This is the first time that tissue from farm animals infected with prion diseases have been
Contact: Andrew McLaughlin
University of Bath