Detection of two dissimilar chronic wasting disease isolates in two captive Rocky Mountain elk (Cervus canadensis) herds

ABSTRACT

Chronic wasting disease (CWD) continues to spread in both wild and captive cervid herds in North America and has now been identified in wild reindeer and moose in Norway, Finland and Sweden. There is limited knowledge about the variety and characteristics of isolates or strains of CWD that exist in the landscape and their implications on wild and captive cervid herds. In this study, we evaluated brain samples from two captive elk herds that had differing prevalence, history and timelines of CWD incidence. Site 1 had a 16-year history of CWD with a consistently low prevalence between 5% and 10%. Twelve of fourteen naïve animals placed on the site remained CWD negative after 5 years of residence. Site 2 herd had a nearly 40-year known history of CWD with long-term environmental accrual of prion leading to nearly 100% of naïve animals developing clinical CWD within two to 12 years. Obex samples of several elk from each site were compared for CWD prion strain deposition, genotype in prion protein gene codon 132, and conformational stability of CWD prions. CWD prions in the obex from site 2 had a lower conformational stability than those from site 1, which was independent of prnp genotype at codon 132. These findings suggest the existence of different CWD isolates between the two sites and suggest potential differential disease attack rates for different CWD strains.

KEYWORDS:

• Cervus elaphus
• cervus canadensis
• chronic wasting disease
• conformational stability
• CWD
• disease prevalence
• elk
• isolates
• prion
• strains

Acknowledgments

The authors would like to thank Tara Ruby-Rigg, Dr. Terry Kreeger, and Dr. Thomas Gidlewski for their assistance with this project.

The findings and conclusions in this publication have not been formally disseminated by the US. Department of Agriculture and should not be construed to represent any agency's determination or policy. Funding: Part of the study was supported by the National Institutes of Health (NIH) grants NS088604 to QK, and NS109532 to WQZ and QK.

Disclosure statement

The authors report no conflict of interest.