Network of Excellence dedicated to research on prion diseases
In september 2003 a new european "Network of Excellence" was launched to protect humans and animals against prion diseases. The project NeuroPrion was selected by the European Commission under the Thematic Priority 5 Food Quality and Safety.
Project no.: FOOD-CT-2004-506579
Total funding: 14.4 M€ for 5 years
Since the appearance of the first cases of 'mad cow disease' in the 1980s, prion diseases, which scientific name is Transmissible Spongiform Encephalopathies (TSEs) », have become a major problem for society both in Europe and worldwide, with important health and economic consequences (the economic loss was estimated to be more than 90 billion euros for Europe during the period 1996-2004, and more than 10 billion dollars for Canada during the period 2003-2007).
NeuroPrion aims to structure and integrate the efforts of the main European prion research teams to achieve durable synergies. Working together, solutions to current problems in society may be more efficiently achieved. Thus, NeuroPrion links more than 120 research teams from 52 research institutions across Europe. The network combines the expertise of more than 90% of the leading research groups in Europe with individual research efforts structured to overcome some existing fragmentation.
The coordination of the research on prion diseases at an european level has already led to major advances in the understanding of these diseases, enabling European and national decision makers to properly manage the crisis during the last decade.
Seven main threats for the future linked to prions
The NeuroPrion network has identified seven main threats for the future linked to prions.
The TSE road map defining the evolution of European policy for protection against prion diseases is based on a certain numbers of hypotheses some of which may turn out to be erroneous. In particular, a form of BSE (called atypical Bovine Spongiform Encephalopathy), recently identified by systematic testing in aged cattle without clinical signs, may be the origin of classical BSE and thus potentially constitute a reservoir, which may be impossible to eradicate if a sporadic origin is confirmed. Also, a link is suspected between atypical BSE and some apparently sporadic cases of Creutzfeldt-Jakob disease in humans. These atypical BSE cases constitute an unforeseen first threat that could sharply modify the European approach to prion diseases.
In small ruminants, a new atypical form of scrapie currently represents up to 50% of detected cases and even involves sheep selected for resistance to classical scrapie. The consequences for animal and human health are still unknown and there may be a potential connection with atypical BSE. These atypical scrapie cases constitute a second threat not envisioned previously which could deeply modify the European approach to prion diseases.
The species barrier between human and cattle might be weaker than previously expected and the risk of transmission of prion diseases between different species has been notoriously unpredictable. The emergence of new atypical strains in cattle and sheep together with the spread of chronic wasting disease in cervids renders the understanding of the species barrier critical. This constitutes a third threat not properly envisioned previously that could deeply modify the European approach to prion diseases.
Prion infectivity has now been detected in blood, urine and milk and this has potential consequences on risk assessments for the environment and food as well as for contamination of surfaces including medical instruments. Furthermore the procedures recommended for decontamination of MBM (Meat and Bone Meal), which are based on older methodologies not designed for this purpose, have turned out to be of very limited efficacy and compromise current policies concerning the reuse of these high value protein supplements (cross-contamination of feed circuits are difficult to control). It should be noted that the destruction or very limited use of MBM is estimated to still cost 1 billion euros per year to the European economy, whereas other countries, including the US, Brazil, and Argentine do not have these constraints. However, many uncertainties remain concerning the guarantees that can be reasonably provided for food and feed safety and scientific knowledge about the causative agents (prions) will continue to evolve. This decontamination and environmental issue is a fourth threat that could modify deeply the European approach to prion diseases.
The precise nature of prions remains elusive. Very recent data indicate that abnormal prion protein (PrPTSE) can be generated from the brains of normal animals, and under some conditions (including contaminated waste water) PrPTSE can be destroyed whereas the BSE infectious titre remains almost unchanged, a finding that underlines the possibility of having BSE without any detectable diagnostic marker. These are just two areas of our incomplete knowledge of the fundamental biology of prions which constitute a fifth threat to the European approach to prion diseases.
The absence of common methods and standardisation in the evaluation of multiple in vivo models with different prion strains and different transgenic mice expressing PrP from different species (different genotypes of cattle, sheep, cervids, etc) renders a complete and comprehensive analysis of all the data generated by the different scientific groups almost impossible. This deeply impairs risk assessment. Moreover, the possibility of generating PrPTSE de novo with new powerful techniques has raised serious questions about their appropriateness for use as blood screening tests. The confusion about an incorrect interpretation of positive results obtained by these methods constitutes a sixth threat to European approach to prion diseases.
The detection of new or re-emerging prion diseases in animals or humans which could lead to a new crisis in consumer confidence over the relaxation of precautionary measures and surveillance programmes constitutes a seventh threat that could modify the European approach to prion diseases.