However, the recent demonstration of PrPSc within the brain of a proportion of scrapie challenged transgenic mice overexpressing human PrP, and the development of a clinical disease in a non-human primate intracerebrally inoculated with natural scrapie isolates, suggest that the zoonotic potential of scrapie prions to humans cannot be discounted [85,86]. Here, PRNP is linked to scrapie.