PRNP and prion disease: Fish display two orthologues of mammalian PrP, and thus they theoretically may support the manifestation of prion diseases upon interaction with abnormal PrPSc, possibly introduced through the consumption of BSE-contaminated meat and bone meals (MBM), that could have been used in aquaculture for years before the application of the total feed ban on the use of rendered mammalian proteins in feeds for farmed animals [17].