Chronic Wasting Disease of Cervids: Current Knowledge and Future Perspectives

Abstract

A naturally occurring transmissible spongiform encephalopathy (TSE) of mule deer was first reported in Colorado and Wyoming in 1967 and has since spread to other members of the cervid family in 22 states, 2 Canadian provinces, and the Republic of Korea. Chronic wasting disease (CWD), caused by exposure to an abnormally folded isoform of the cellular prion protein, is characterized by progressive neurological disease in susceptible natural and experimental hosts and is ultimately fatal. CWD is thought to be transmitted horizontally in excreta and through contaminated environments, features common to scrapie of sheep, though rare among TSEs. Evolving detection methods have revealed multiple strains of CWD and with continued development may lead to an effective antemortem test. Managing the spread of CWD, through the development of a vaccine or environmental cleanup strategies, is an active area of interest. As such, CWD represents a unique challenge in the study of prion diseases.

Temporal Resolution of Misfolded Prion Protein Transport, Accumulation, Glial Activation, and Neuronal Death in the Retinas of Mice Inoculated with Scrapie

“…The RT-QuIC assay was performed using previously published protocols from published reports 24,26,27 with slight modifications. The reaction mixtures consisted of final concentrations of 350 mmol/L NaCl, 0.1 mmol/L EDTA, 10 mmol/ L thioflavin T, 0.1 mg/mL rPrP, and 0.002% SDS in 1Â phosphate-buffered saline.…”

Antemortem Detection of Chronic Wasting Disease Prions in Nasal Brush Collections and Rectal Biopsy Specimens from White-Tailed Deer by Real-Time Quaking-Induced Conversion

“…It is the only prion disease of animals the control and eradication of which, through movement restrictions, genotypic breeding schemes, or herd reduction/depopulation efforts, for example, are problematic (1,2). While the origins of CWD are uncertain, the disease has been present in cervid populations of northern Colorado and southern Wyoming for nearly 50 years (3,4) and has now been identified in both captive and free-ranging cervids in 23 states, two Canadian provinces, and the Republic of Korea (5,6). With intensified national and international surveillance efforts, CWD continues to be identified in areas previously considered free of infection, including recent discoveries in Iowa, Texas, Pennsylvania, and Ohio (7,8,9,10).…”

Challenges in managing the risks of chronic wasting disease

“…Many considerations are involved in the spread of CWD, such as (for review see Haley and Hoover, 2015):…”

“…Ante-mortem CWD detection and surveillance detection methods (Haley et al, 2012;Haley and Hoover, 2015;Henderson et al, 2013;John et al, 2013) are under development. In the past, the main methods for CWD diagnosis have been immunohistochemistry or ELISA on post-mortem brain samples of deceased animals.…”

“…The disease is most prevalent among deer species, affecting in particular mule deer, but also black-tailed deer and white-tailed deer. CWD belongs to a group of related neurodegenerative diseases called transmissible spongiform encephalopathies (TSEs), a group which also includes bovine spongiform encephalopathy (BSE), scrapie and variant Creutzfeldt-Jakob disease (for recent review see Haley and Hoover, 2015). CWD is prevalent in both farmed and wild cervids and is considered to be one of the most contagious forms of TSE known (Miller and Williams, 2002).…”