Detection of prion protein in the cerebrospinal fluid of elk (Cervus canadensis nelsoni) with chronic wasting disease using protein misfolding cyclic amplification

Cerebrospinal fluid (CSF) has been examined as a possible source for preclinical diagnosis of prion diseases in hamsters and sheep. The present report describes the detection of chronic wasting disease (CWD) in the CSF of elk and evaluates its usefulness as an antemortem test for CWD. The CSF from 6 captive and 31 free-ranging adult elk was collected at necropsy and evaluated for the presence of the abnormal isoform of the prion protein that has been associated with CWD (PrPCWD) via protein misfolding cyclic amplification. Additionally, the obex from each animal was examined by immunohistochemistry (IHC). Four out of 6 captive animals were CWD-positive and euthanized due to signs of terminal CWD. The remaining 2 were CWD negative. None of the 31 free-range animals showed overt signs of CWD, but 12 out of 31 tested positive for CWD by IHC. Protein misfolding cyclic amplification detected PrPCWD from 3 of the 4 captive animals showing clinical signs of CWD and none of the nonclinical animals that were CWD positive by IHC. The data suggests that CWD prions can be detected in the CSF of elk, but only relatively late in the course of the disease.