Set against a backdrop of confirmed cases of chronic wasting disease (CWD) across Minnesota, the team of University of Minnesota researchers developing a faster diagnostic reached a key milestone this winter — analyzing tissue samples from CWD-positive white-tailed deer and obtaining confirmation of protein-misfolding within just nine hours. This milestone places the U of M team among an elite community of research laboratories around the world that use a leading-edge technology, real-time quaking-induced conversion (RT-QuIC), for both wildlife and human diseases. This testing system is one of the most sensitive and fastest currently available. 

The team’s goal is to develop a test for identifying the misfolded prions associated with the disease in real time and this important step brings scientists one step closer to a field test to better track down CWD. Collaborating with National Institutes of Health Rocky Mountain Laboratories (Hamilton, Mont.) helped give the team access to the RT-QuIC technology, which will facilitate several exciting research avenues. 

RT-QuIC is a highly sensitive test for detecting prion diseases such as CWD, scrapie in sheep, bovine spongiform encephalopathy in cattle, and sporadic Creutzfeldt-Jakob disease in humans. The test involves placing suspected misfolded prions in a prion-rich solution, shaking and incubating the mixture to promote molecular interaction, and then monitoring for conversion of misfolded prions. RT-QuIC has proven useful to detect CWD prions in a variety of sample types from both live and harvested deer, including feces, blood, saliva and tissues. At present, RT-QuIC is only used for research purposes. It has not been validated for official, regulatory disease diagnostic testing in wild or farmed cervids.

“We were working with known positive samples,” explains team co-leader Peter Larsen, PhD, an assistant professor in the Department of Biomedical and Veterinary Sciences in the University of Minnesota College of Veterinary Medicine (CVM). “To independently confirm that our procedures are successful is a critical first step and we greatly appreciate the help that NIH Rocky Mountain Labs provided our team. This milestone was made possible through Rapid Agricultural Response funds from the Minnesota Ag Experiment Station and bipartisan support from the Minnesota Legislature.” The team is working to develop prototypes of more rapid and accurate tests that will identify CWD-causing prions in various kinds of samples.

More common, currently validated diagnostic methods are slower, less sensitive, and more costly, which in the case of CWD, limits hunters and resource managers from making the timely decisions needed to contain the disease. In the future, RT-QuIC and further developed tests may be validated by regulatory agencies such as the United States Department of Agriculture and be available for official disease diagnostic testing.

After further in-house validation of the RT-QuIC testing, the U of M team will turn its attention to analyzing tissue samples from approximately 500 deer that were generously provided by the Minnesota Department of Natural Resources. Previous testing by currently validated methods has found 12 CWD-positive samples within the collection. Confirming whether RT-QuIC can correctly identify the positive samples is the team’s next step. Further research initiatives that lie beyond the current scope of funding include utilizing the RT-QuIC testing capabilities for environmental testing, transmission studies and ecological impact investigation. 

“In order to continue battling CWD, we must obtain additional funding that will utilize the newly developed test in studies advancing the current understanding of CWD in Minnesota,” explains Marc Schwabenlander, MPH, CWD project and outreach manager at the Minnesota Center for Prion Research and Outreach.

“Achieving a statistically positive result within hours demonstrates the advantages of this newer technology,” Larsen says. “The ultimate long-term goal for CWD diagnostics is the availability of next-generation diagnostic tools that can quickly and reliably process many samples. RT-QuIC functionality helps provide the foundation for developing and validating prototypes of a new class of CWD diagnostic tools.”