Second passage of scrapie in white-tailed deer is discernable from chronic wasting disease

Authors: LAMBERT, ZOE - Oak Ridge Institute For Science And Education (ORISE); WEST GREENLEE, HEATHER - Iowa State University; Cassmann, Eric; Greenlee, Justin

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/4/2022
Publication Date: 9/13/2022
Citation: Lambert, Z., West Greenlee, H.M., Cassmann, E.D., Greenlee, J.J. 2022. Second passage of scrapie in white-tailed deer is discernable from chronic wasting disease. Prion 2022 Conference abstracts: pushing the boundaries. 16(1):181. https://doi.org/10.1080/19336896.2022.2091286.
DOI: https://doi.org/10.1080/19336896.2022.2091286

Interpretive Summary:

Technical Abstract: White-tailed deer (WTD) are susceptible to the scrapie agent from sheep after oronasal inoculation. Upon initial passage from sheep, 100% of inoculated deer developed disease. Western-blot profiles were tissue dependent: profiles from cerebrum and retina were similar to the scrapie inoculum, whereas brainstem and lymph node appeared CWD-like. The purpose of this study was to examine how the agent of scrapie in WTD may adapt following subsequent passage in WTD and determine if it can be differentiated from CWD. The inoculum was brain homogenate from a WTD that was challenged with classical scrapie from a sheep (ARQ/ARQ genotype) and developed clinical signs at 32.5 months post inoculation. Three WTD received 1 mL of 10% w/v obex inoculum oronasally, four received 1 mL of 10% w/v cerebrum intranasally. The negative control animal received no inoculum. Deer were euthanized and necropsied following the development of clinical signs, including weight loss, hair loss, excessive salivation, diarrhea, and progressive weakness. Enzyme immunoassay (IDEXX), western blot, and immunohistochemistry using the primary antibodies Sha 31, 12B2 and F99 were used. Cervidized mice (Tg12) were inoculated with material from WTD in each group. All inoculated WTD displayed clinical disease and were positive for abnormal prion protein by enzyme immunoassay. The average survival time of the obex-inoculated group was 24.1 months post-inoculation, while that of the cerebrum-inoculated group was 29.2 months post-inoculation. Both groups had shorter incubation times compared to the inoculum donor (32.5 months). Western blotting of retinas from all WTD (second pass) resulted in a similar molecular profile as the retinas of WTD that were inoculated with the agent of scrapie from sheep (first pass). Immunohistochemical staining also was similar between inoculation groups and the initial passage from sheep, but different from WTD inoculated with the agent of CWD. Following bioassays in cervidized mice (Tg12), all incubation periods were over 300 days, substantially longer than the approximately 150 day incubation period typical with CWD isolates. Based upon analysis of retinal tissues, it is possible to differentiate the agents of scrapie and CWD in WTD by both western blot and immunohistochemistry. Bioassay in cervidized mice further supports this based on incubation periods of WTD-scrapie being approximately twice that of WTD CWD.