Prion protein in cardiac muscle of elk (Cervus elaphus nelsoni) and white-tailed deer (Odocoileus virginianus) infected with chronic wasting disease

To investigate the possible presence of disease-associated prion protein (Prp(d)) in striated muscle of chronic wasting disease (CWD)-affected cervids, samples of diaphragm, tongue, heart and three appendicular skeletal muscles from mule deer (Odocoileus hemionus), white-tailed deer (Odocoileus virginianus), elk (Cervus elaphus nelsoni) and moose (Alces alces shirast) were examined by ELISA, Western immunoblot and immunohistochemistry (IHC). Prpd was detected in samples of heart muscle from seven of 16 CWD-infected white-tailed deer, including one free-ranging deer, and in 12 of 17 CWD-infected elk, but not in any of 13 mule deer samples, nor in the single CWD-infected moose. For white-tailed deer, Prpd was detected by Western blot at multiple sites throughout the heart; IHC results on ventricular sections of both elk and white-tailed deer showed positive staining in cardiac myocytes, but not in conduction tissues or nerve ganglia. Levels of Prpd in cardiac tissues were estimated from Western blot band intensity to be lower than levels found in brain tissue. Prpd was not detected in diaphragm, triceps brachii, semitendinosus, latissiumus dorsi or tongue muscles for any of the study subjects. This is the first report of Prpd in cardiac tissue from transmissible spongiform encephalopathy-infected ruminants in the human food chain and the first demonstration by immunological assays of Prpd in any striated muscle of CWD-infected cervids.