These results firstly show that VPSPr PrPSc is detectable by CDI, but only after mild treatment with proteinase K. Therefore VPSPr, in common with all other human prion diseases, is associated with a misfolded form of PrP in which the 3F4 epitope (amino acids 106-112) is concealed. This evidence concerns the gene PRNP and prion disease.