PRNP and scrapie: Mitochondrial dysfunction was identified by Ingenuity Pathway Analysis as the top toxicity pathway in prion-exposed Drosophila. It was found that prion-exposed 40-day-old adult VRQ ovine PrP Drosophila, exposed to scrapie at the larval stage, were characterised by down-regulation of genes encoding principal components of the electron transport chain including NADH dehydrogenase, ATP synthase and various anti-oxidants including superoxidase dismutase-2 and glutaredoxin 1.