PRNP and prion disease: These assays, including western blotting [23], immunohistochemistry [25], and enzyme immunoassay (EIA) [26], capable of distinguishing the normally folded cellular prion protein (PrPC) and the misfolded, infectious isoform (PrPres/PrPSc), are still considered the “gold standard” diagnostic approaches for CWD and other prion diseases (Figure 2).