Antemortem Detection Of Prp^cwd in Preclinical, Ranch-Raised Rocky Mountain Elk (Cervus elaphus nelson) by Biopsy of the Rectal Mucosa

Authors

Terry R. Spraker, Colorado State University, Fort Collins, CO
Kurt C. VerCauteren, USDA-APHIS-Wildlife ServicesFollow
Thomas Gidlewski, Veterinary ServicesFollow
David A. Schneider, U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Fort Collins, CO; Agricultural Research Services, U.S. Department of Agriculture, Pullman, WA
Randy Munger, Veterinary Services
Aru Balachandran, the OIE and National Reference Laboratory for Scrapie and CWD, Canadian Food Inspection Agency, Nepean, ON, Canada
Katherine I. O’Rourke, U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Fort Collins, CO; Agricultural Research Services, U.S. Department of Agriculture, Pullman, WA

Document Type

Article

Date of this Version

2009

Comments

Published in J Vet Diagn Invest 21:15–24 (2009).

Abstract

Antemortem biopsy of the rectal mucosa was evaluated as a method for the preclinical diagnosis of chronic wasting disease (CWD) in a herd of ranch-raised Rocky Mountain elk (Cervus elaphus nelson) quarantined because of exposure to CWD. Biopsy samples were obtained from 41 elk during the winter of 2005–2006 and from 26 elk from that herd still alive and available for testing during the winter of 2006–2007. Samples were examined for PrP^CWD, the protein marker for CWD infection, by immunohistochemistry. PrP^CWD was detected in follicles of the rectoanal mucosa-associated lymphoid tissue in biopsy samples from 1 elk with clinical signs of chronic wasting disease and 5 clinically normal elk. The diagnosis was confirmed in all 6 animals by postmortem analysis of brain and peripheral lymph nodes. PrP^CWD was also observed in the submucosal plexus and myenteric plexus of the enteric nervous system, and in close association with nonmyelinated mucosal and submucosal nerve fibers. In antemortem rectal biopsy samples from positive animals, immunostaining was consistently observed in approximately 60% of the mucosa-associated lymphoid tissue follicles if 10 or more total follicles per biopsy were present for evaluation. Most antemortem biopsy samples obtained from elk younger than 6.5 years contained at least 10 follicles per rectal mucosal biopsy. These findings support the analysis of antemortem biopsy of the rectal mucosa samples as part of an integrated strategy to manage chronic wasting disease in Rocky Mountain elk.