2013 Annual Report
1a.Objectives (from AD-416):
The objective of this cooperative research project is to describe the dissemination pattern of abnormal prion protein in the tissues of captive and free ranging Rocky Mountain elk.
1b.Approach (from AD-416):
Describe the distribution and characteristics of abnormal prion protein in the neural and extraneural tissues of captive and free ranging elk with clinical and preclinical chronic wasting disease.
Experimental Design: The CWD status of Rocky Mountain elk will be determined by live animal biopsy of rectal mucosal lymphoid tissues from Rocky Mountain elk. Immunohistochemistry of the biopsy sample is performed using methods developed by the cooperator and ARS. Elk with positive test results are euthanized and tissues collected from neural and extraneural tissues. A panel of 25 tissues per animal is examined with a battery of antibody based and histologic methods for evidence of abnormal prion protein accumulation and evidence of spongiform encephalopathy. ARS will analyze the open reading frame of the prion protein in each animal.
This work relates to sub-objective 2 of the parent project in supporting efforts to mitigate environmental prion contamination by providing predictions of duration of infection and therefore transmissibility and prion load. Chronic wasting disease (CWD) is a prion disorder reported in several species and subspecies of captive and free ranging cervid ruminants in North America. The disease course differs among the species, with implications for pathogenesis, transmission, and diagnosis. This project has addressed the dissemination of abnormal prion proteins in the nervous and lymphoid tissues of Rocky Mountain elk, a species maintained under farmed conditions in many areas. The study produced data useful for estimating the duration of infection based on examination of specific areas of the brain, determined estimates of diagnostic accuracy for live-animal biopsy of the rectal mucosa in captive and free-ranging cervids, and uncovered some of the pathophysiologic effects of specific cervid prion gene polymorphisms. The findings will be useful in the CWD eradication and control program. The project was monitored by conference calls with the investigators and the regulatory personnel participating in the project and electronic exchange of data and manuscripts.