Preliminary findings on the experimental transmission of chronic wasting disease agent of mule deer to cattle

To determine the transmissibility of chronic wasting disease (CWD) to cattl e and to provide information about clinical course, lesions, and suitabilit y of currently used diagnostic procedures for detection of CWD in cattle, 1 3 calves were inoculated intracerebrally with brain suspension from mule de er naturally affected with CWD. Between 24 and 27 months postinoculation, 3 animals became recumbent and were euthanized. Gross necropsies revealed em aciation in 2 animals and a large pulmonary abscess in the third. Brains we re examined for protease-resistant prion protein (PrPres) by immunohistoche mistry and Western blotting and for scrapie-associated fibrils (SAFs) by ne gative-stain electron microscopy. Microscopic lesions in the brain were sub tle in 2 animals and absent in the third case. However, all 3 animals were positive for PrPres by immunohistochemistry and Western blot, and SAFs were detected in 2 of the animals. An uninoculated control animal euthanized du ring the same period did not have PrPres in its brain. These are preliminar y observations from a currently in-progress experiment. Three years after t he CWD challenge, the 10 remaining inoculated cattle are alive and apparent ly healthy. These preliminary findings demonstrate that diagnostic techniqu es currently used for bovine spongiform encephalopathy (BSE) surveillance w ould also detect CWD in cattle should it occur naturally.