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Evaluation of the possible transmission of prions (scrapie and bse) to different fish species

Deliverables

Our results are relevant for public policy making concerning food safety and directed scientific research funding. At present there is a temporary EU-wide ban on the use of fishmeal in ruminant feed that has been in place since 2001. Any consideration to lifting of this ban must include a scientific assessment on the potential risk of spreading BSE to ruminants through consumption of fishmeal and our project results provide crucial information for such an assessment. We have found that after ingestion, PrPSc can remain in fish intestine for a period of days, and that the duration of this persistence varies with both the species of fish and the TSE source. The bulk of ingested PrPSc is cleared from the fish and does not cross the intestinal barrier of fish. However, results from mouse bioassays indicate that residual TSE- associated infectivity present in challenged fish during this ’persistence period’(days) is able to cross the gastrointestinal barrier to contaminate other tissues. Thus, there could be a potential hazard of residual TSE infectivity in fishmeal produced from fish recently fed with TSE-contaminated feed. This information must be taken into account during any consideration of lifting the current ban on fishmeal.
Our results are relevant for public policy making concerning food safety and directed scientific research funding. At present there is a temporary EU-wide ban on the use of fishmeal in ruminant feed that has been in place since 2001. Any consideration to lifting of this ban must include a scientific assessment on the potential risk of spreading BSE to ruminants through consumption of fishmeal and our project results provide crucial information for such an assessment. We have found that months after BSE ingestion, sea bream develop protease-K resistant brain lesions, whereas control fish do not. This information must be taken into account during any consideration of lifting the current ban on fishmeal. Additionally, it points up the need for further scientific investigation on the transmissibility of this abnormal, TSE-associated brain pathology to other fish and to higher vertebrates.