BRC-BIO Chronic wasting disease (CWD) in Southwest Montana: Investigating mechanisms of environmental transmission for CWD control.

About This Grant

Transmissible Spongiform encephalopathies (TSE) are a group of progressive and incurable neurological diseases caused by misfolded proteins called prions. These proteins accumulate in the brain and cause memory loss, impaired movement and eventually death. Prions can cause disease in several animal species and are the causative agents behind mad cow disease, scrapie in domestic sheep, and Creutzfeldt-Jakob disease in humans. The specific prion disease affecting cervids like deer, elk and moose is called Chronic Wasting Disease (CWD). Historically, this disease was considered relatively obscure in Mule Deer, and has appeared only sporadically in isolated populations. However, it has recently spread to become a serious and persistent threat in both deer and elk across Southwest Montana. The high fatality of CWD and its ease of transmission makes it capable of fundamentally altering entire ecosystems if left unchecked. Unfortunately, the pathways of infection, both between individuals and through the environment are not clearly understood. While numerous methods exist to test for CWD in individuals, very few studies have attempted to detect CWD prions in soil, vegetation or water, and appropriate methods for environmental surveillance are lacking. The resulting knowledge gap hinders the development of effective management techniques to control the spread of the disease or even eradicate it entirely. The goal of this study is to better understand the ecology of CWD with the aim of discovering varying pathways of environmental transmission and possible methods of environmental control. The prevalence of CWD has been steadily increasing in Elk and Mule Deer populations throughout Southwest Montana and now presents a significant risk to the regional ecology. It is unknown to what degree prions may leach from carcasses and what environmental conditions may promote their persistence or degradation. If prions leaching from carcasses remain infective, then they represent a significant unmonitored source of infection that needs to be managed appropriately to ensure adequate removal from the environment. The specific aims of this project are to: determine if infected carcasses are a source of environmental contamination; determine if CWD prion abundance in the environment is correlated with disease prevalence in local deer populations; and to identify environmental factors that affect prion degradation. To address these aims, we will place infected carcasses at six specific sites and sample the surrounding soil and vegetation over time to establish prion distribution and abundance. Low concentration prions in environmental samples will be amplified using Protein Misfolding Cyclic Amplification and detected using ELISA and western blotting. The stability and activity of infectious prions will be assayed after exposure to a range of environmental conditions (freeze, thaw, ultraviolet light, flame, etc.) to establish the conditions under which they degrade. As little is known about which conditions these prions are susceptible to, understanding these ‘weaknesses’ will be invaluable in both managing CWD and potentially eradicating it from an area. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.