UMN veterinary scientists propose faster Chronic Wasting Disease diagnostic test

February 8, 2019

Current diagnostic tests for Chronic Wasting Disease (CWD), which is a growing threat to Minnesota’s white-tailed deer population, can only confirm CWD’s advance after an infected animal is dead. And the tests require days or weeks to deliver results. Thus, wildlife managers can only learn where CWD has been, not where it is currently circulating, which makes controlling the contagious, neurodegenerative disease challenging.

A team of University of Minnesota experts, led by scientists from the College of Veterinary Medicine, is seeking funds to develop a test that can rapidly screen live animals for the presence of CWD. The team is working closely with staff from the Minnesota Department of Natural Resources and the Minnesota Board of Animal Health to refine the proposal, which Minnesota legislators are considering.

CWD results from a malformed prion that kills neurons in the infected animal’s brain—leading to disorientation, abnormal behavior, and eventual death. Infected animals can live for at least 16 months before dying, and their blood, tissues, and fecal material can remain a source of new infections for years after death. The prion behind CWD is closely related to the prion that causes mad cow disease, and also related to human prion diseases such as Alzheimer’s and Parkinson’s. The U.S. Centers for Disease Control recommends against eating meat from CWD-infected animals.

A difficult, but achievable goal
Recent advances in biomedical technology and the application of nanotechnology to DNA analysis have put a rapid, field-based test for the presence of CWD within reach. But developing a fast-acting test that reliably finds the CWD prions without delivering too many “false positive” results is a challenge. The team is requesting $1.8 million and two years to develop the test and a prototype device. The funding will allow staff to work full-time on the project and purchase the specialized equipment they need.

“Our current tests force wildlife managers to order the killing of deer without confirming their infection status,” says Peter Larsen, PhD. “And the specialized hunts often occur long after infection has spread—possibly beyond the hunting boundaries.” Larsen is leading the research team. He is a genomicist and bioinformatician with expertise in infectious disease, neurogenerative disease, and the application of nanotechnology for molecular diagnostics. He is a newly hired member of the University’s Department of Veterinary and Biomedical Sciences. The project's co-leader is Pamela Skinner, PhD, who is a prion disease researcher in the Department of Veterinary and Biomedical Sciences.

The team’s goal is to isolate and detect CWD prions within a microfluidic environment. To be really useful, the test needs to work with a variety of substances including blood, saliva, and feces.

“We have the expertise and the necessary biocontainment facilities to safely handle the CWD prions,” Larsen says. “It will be difficult to achieve, but we are confident of our future success.”

A critical first step
CWD has spread across the central US over the past 50 years and is currently found in 26 states. It’s also found in Canada, several Scandinavian countries, and parts of Asia. It is circulating among animals in the cervidae family—i.e. white-tailed deer, moose, elk, and reindeer.

“I have watched CWD move into Minnesota and I’m frustrated that we haven’t found strategies to slow down or contain the disease,” says Jeremy Schefers, DVM, PhD. Schefers is a pathologist with the Minnesota Veterinary Diagnostic Laboratory, and has spent over 10 years looking at thousands of tissue samples to confirm the presence of CWD. “Unfortunately, our lack of a rapid test that works on live animals, or our ability to test other things such as soil, meat processing equipment, and samples from other animals that might carry the prion, clouds our understanding of CWD transmission,” Schefers adds.

A rapid and reliable field-based test would help answer numerous CWD-related questions. How long does an infected animal shed the CWD prions that can infect other animals? How long do the prions survive in the environment? What techniques inactivate the CWD prions, either in animals or in the environment?

“We need to do something different to get ahead of this disease,” Schefers says, “and most of those different strategies won’t be successful without the ability to quickly determine if CWD is present or not. A better test is the critical first step.”

The research team also includes Davis Seelig, DVM, PhD, AVCP, a pathologist in the Department of Veterinary and Clinical Sciences, and Sang-Hyun Oh, PhD, an expert in nanotechnology and biosensing in the Department of Electrical and Computer Engineering.