Whatever the origin (species) of the BSE/vCJD agent, the ovine PrP substrates (ARQ and VRQ) provided the best detection performances, i.e. positive for reactions seeded with a 10−6 to 10−8 dilution of the original brain homogenates (figures 1, 2C). The gene discussed is PRNP; the disease is variant Creutzfeldt-Jakob disease.