U Minnesota manci_li_rt-quic_cropped.jpg University of Minnesota
University of Minnesota doctoral student Manci Li uses the RT-QuIC machine within the newly outfitted prion research laboratory.

Research milestone advances CWD diagnostic test

Team working to develop prototypes of more rapid and accurate tests to identify CWD-causing prions in various kinds of samples.

A team of veterinary diagnostic researchers at the University of Minnesota has reached a key milestone in developing a faster diagnostic test for identifying the misfolded prions associated with chronic wasting disease (CWD).

Through a collaboration with the National Institutes of Health (NIH) Rocky Mountain Laboratories in Hamilton, Mont., the team now has real-time quaking-induced conversion (RT-QuIC) technology that will facilitate a number of research avenues, according to an announcement from the university.

With this technology, the team analyzed tissue samples from CWD-positive white-tailed deer and obtained confirmation of protein misfolding within nine hours.

“We were working with known positive samples,” explained team co-leader Dr. Peter Larsen, an assistant professor in the department of biomedical and veterinary sciences in the University of Minnesota College of Veterinary Medicine. “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.

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 university said. 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 growth of misfolded prions.

The university said RT-QuIC has proved 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 used only for research purposes, the university pointed out, because it has not been validated for official, regulatory disease diagnostic testing in wild or farmed cervids.

“Achieving a statistically positive result within hours demonstrates the advantages of this newer technology,” Larsen said. “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.”

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

This milestone places the University of Minnesota team among a key community of research laboratories around the world that use RT-QuIC for both wildlife and human diseases. The team is funded by approximately $2 million awarded through the Minnesota Agricultural Experiment Station Rapid Agricultural Response Fund and appropriated by the Minnesota Legislature via the Legislative Citizens Commission on Minnesota Resources in 2019.

After further in-house validation of the RT-QuIC testing, the team will turn its attention to analyzing tissue samples from approximately 500 deer that were 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.

Additional research initiatives include utilizing the RT-QuIC testing capabilities for environmental testing, transmission studies and ecological impact investigation, the announcement said.

In a provided list of "frequently asked questions," the research team pointed out that RT-QuIC is currently used for detecting other prion and protein misfolding diseases. Future platforms are likely to advance diagnostic testing across the spectrum of neurodegenerative diseases in humans and animals, they said.

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