Experimental Oral Transmission of Chronic Wasting Disease to Reindeer (Rangifer tarandus tarandus)

Abstract

Chronic wasting disease (CWD), a transmissible spongiform encephalopathy of cervids, remains prevalent in North American elk, white-tailed deer and mule deer. A natural case of CWD in reindeer (Rangifer tarandus tarandus) has not been reported despite potential habitat overlap with CWD-infected deer or elk herds. This study investigates the experimental transmission of CWD from elk or white-tailed deer to reindeer by the oral route of inoculation. Ante-mortem testing of the three reindeer exposed to CWD from white-tailed deer identified the accumulation of pathological PrP (PrPCWD) in the recto-anal mucosa associated lymphoid tissue (RAMALT) of two reindeer at 13.4 months post-inoculation. Terminal CWD occurred in the two RAMALT-positive reindeer at 18.5 and 20 months post-inoculation while one other reindeer in the white-tailed deer CWD inoculum group and none of the 3 reindeer exposed to elk CWD developed disease. Tissue distribution analysis of PrPCWD in CWD-affected reindeer revealed widespread deposition in central and peripheral nervous systems, lymphoreticular tissues, the gastrointestinal tract, neuroendocrine tissues and cardiac muscle. Analysis of prion protein gene (PRNP) sequences in the 6 reindeer identified polymorphisms at residues 2 (V/M), 129 (G/S), 138 (S/N) and 169 (V/M). These findings demonstrate that (i) a sub-population of reindeer are susceptible to CWD by oral inoculation implicating the potential for transmission to other Rangifer species, and (ii) certain reindeer PRNP polymorphisms may be protective against CWD infection.

Can plants serve as a vector for prions causing chronic wasting disease?

“…1 Experimental transmission has also been demonstrated in reindeer. 2 Prion diseases, also termed Transmissible Spongiform Encephalopathies (TSE), are caused by misfolding of the cellular prion protein, PrP C , into the disease-causing conformation designated PrP TSE . Misfolded PrP TSE is broadly accepted as the disease causing agent responsible for misfolding of PrP C into PrP TSE .…”

Challenges in managing the risks of chronic wasting disease

“…On the other hand, intracerebral inoculation with white tailed deer CWD results in an 85% infection rate in cattle, suggesting that some cervid prion strains have more potential to cross the species barrier than others (Sigurdson, 2008). Another cervid that is likely to acquire CWD in future is the northern caribou , since oral exposure has resulted in disease transmission in reindeer, a close relative to the caribou (Mitchell et al, 2012). Genotype analysis has found that caribou PRNP alleles (alleles that are strongly associated with disease prevalence) are nearly identical to those of elk, moose, white-tailed deer and mule deer.…”

“…Aboriginal peoples in North America may be affected through similar impacts on their traditional use of land and wildlife. Should the disease eventually spread to reindeer and woodland caribou, impacts on aboriginal peoples and the general public will greatly increase (Mitchell et al, 2012). Although no formal quantitative risk assessment of CWD has been performed to date, the level of at least some of these identified risks can be estimated qualitatively with a high degree of confidence, on the basis of the extensive, accumulated scientific studies of hazard and exposure.…”

Potential role of soil properties in the spread of CWD in western Canada

“…1 Recent transmission studies have demonstrated the ability of CWD to transmit to reindeer by the oral route. 2 The Woodland (R.t. caribou) and Barren ground (R.t. groenlandicus) caribou range extends south to central parts of Alberta, Saskatchewan and Manitoba 3 ( Fig. 1).…”