Following exposure to vCJD prions (Fig. 3A), M129 human PrP Drosophila accumulated more prion seeding activity compared to V129 human PrP Drosophila, while the level in nonhuman primate PrP Drosophila was of the order: chimpanzee > cynomolgus macaque > squirrel monkey > lemur. This evidence concerns the gene PRNP and variant Creutzfeldt-Jakob disease.