Historical and contemporary chronic wasting disease prions from the western United States demonstrate similar strain properties

Chronic wasting disease (CWD) is a uniformly fatal prion disease of cervids including deer, elk, reindeer and moose. CWD has been detected in cervids of North America (NA), South Korea and Scandinavia. CWD in NA continues to increase in prevalence in multiple locations and is relatively widespread in both wild and captive cervid populations. Consequently, the potential for CWD cross-species exposure to humans or animals that consume or cohabitate with infected cervids continues to increase. Fortunately, CWD infection in humans has not been detected to date, and both laboratory models and epidemiological studies suggest that a strong species barrier exists between cervids and humans. In recent years, several different strains of CWD have been identified and characterized. Unfortunately, new strains of CWD prions may harbour different abilities to cross species barriers, presenting a situation where the risks to humans and animals may also vary. To gain a better understanding of the variation in CWD strains circulating in NA, we performed strain characterization of ten CWD isolates obtained over the past 4–30 years from white-tailed deer, mule deer and elk representing infections from several geographical regions in the western United States. Our results showed that all the cervid isolates we tested had similar prion strain characteristics, suggesting that the CWD prions circulating in the western United States have remained very similar across multiple locations and stable over time.