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Transmissible spongiform encephalopathies

Understanding prion strains and species barriers and devising novel diagnostic approaches

EC contribution
: € 2 158 500
: 36 months
Starting date
: November 1, 2006
: IP
: prion, strain, species barrier, atypical, biological products
Project Number
: FOOD-CT-2006-23183


Transmissible spongiform encephalopathies (TSEs) are fatal neurodegenerative diseases that include Creutzfeldt-Jakob disease (CJD) of humans, scrapie of sheep and goats, bovine spongiform encephalopathy (BSE) or 'Mad cow disease', chronic wasting disease (CWD) of deer in North America, and others. TSEs are caused by prions (Prusiner, 1982), unique proteinaceous pathogens that appear to propagate without the help of nucleic acid genes. Rather, prions 'replicate' by refolding a normal protein of the host, PrPC, into a pathogenic protein called PrPSc. This exclusive mechanism explains how TSE can be either inherited, acquired through infection, or occur sporadically.

The emergence of BSE in the late 1980s and its subsequent transmission to humans (as variant CJD) has illustrated the grave risks that prions pose to public health. Because incubation time is exceedingly long, most diagnosis methods rely on the immune detection of PrPSc (which is often distinguished from PrPC by its resistance to proteolysis).

Prion strains:
A puzzling property of prions is that they occur in different 'strains' within a given host. Prion strains differ in clinical features and disease course, and also in their contagious potential. The current view is that prion strains differ in the three-dimensional folding of PrPSc. Strains greatly complicate the prion problem and increase the dangers presented by TSE, because they are difficult to diagnose and since some strains are 'promiscuous', they jumpwith ease among species. StrainBarrier is an EUfunded consortium that strives to achieve the following: (1) to better understand the structure, biology and epidemiology of prion strains, and (2) to devise accurate methods to distinguish between them.

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