Silent Prions Show Cross-Species Chronic Wasting Disease Risk in Lab Tests, Study Finds
New research published in *Nature Communications* identifies a previously unknown mechanism by which prions associated with chronic wasting disease (CWD) could potentially infect other species, including humans, according to a study led by scientists at the University of Alberta and the National Institutes of Health (NIH). The findings, which involved lab tests on prion proteins from deer and elk, reveal that certain “silent” prions—non-infectious in their native form—can become pathogenic when exposed to specific genetic variations in human and livestock cells.
“This is the first time we’ve seen a direct link between CWD prions and the potential to cross into human biology under controlled conditions,” said Dr. Steven B. Jones, a neurologist at the University of Alberta and co-author of the study. “While the results are preliminary, they highlight the need for heightened surveillance of prion diseases in wildlife and agricultural settings.”
How the Study Uncovered the Risk
The research team analyzed prion proteins from CWD-infected deer and elk, focusing on a variant known as “silent” because it does not trigger disease in its natural host. Using cell cultures and transgenic mice, the scientists introduced these prions into human and bovine cells. In some cases, the prions aggregated into infectious forms, suggesting a pathway for cross-species transmission.
“The key factor was the presence of specific amino acid sequences in human and cattle proteins that facilitated prion conversion,” explained Dr. Laura M. Chen, a prion biologist at the NIH and lead author of the study. “This doesn’t mean CWD is currently infecting humans, but it shows the biological machinery exists for such a jump.”
Implications for Public Health and Agriculture
Chronic wasting disease, first identified in the 1960s, has spread across North America, affecting over 250,000 deer and elk. While no human cases have been confirmed, the study raises concerns about the potential for zoonotic transmission. The Centers for Disease Control and Prevention (CDC) has previously warned that prion diseases like CWD and Creutzfeldt-Jakob disease (CJD) share structural similarities, though no direct link has been proven.
“This study adds to a growing body of evidence that prion diseases are more adaptable than we thought,” said Dr. Michael T. Reynolds, an epidemiologist at the CDC. “We’re urging hunters and agricultural workers to follow strict safety protocols when handling wildlife or livestock, including avoiding contact with brain and spinal tissues.”
What’s Next for Research and Policy?
The study’s authors emphasize that further research is needed to determine whether these lab findings translate to real-world scenarios. The NIH has allocated $2.3 million for follow-up studies, including fieldwork in regions with high CWD prevalence. Meanwhile, the U.S. Department of Agriculture (USDA) is reviewing its guidelines for prion surveillance in livestock.
“We’re not at a crisis point, but this is a wake-up call,” said Dr. Jones. “Prion diseases are notoriously difficult to detect and control. If we can’t rule out cross-species transmission, we need to invest in better diagnostic tools and prevention strategies.”
Why This Matters for Global Health
The discovery comes amid growing concerns about the spread of zoonotic diseases, including COVID-19 and avian influenza. Prion diseases, which can take decades to manifest, pose unique challenges for public health officials. A 2021 study in *The Lancet* found that prions from sheep (scrapie) could potentially infect humans under laboratory conditions, though no cases have been documented.
“This isn’t just about deer or elk,” said Dr. Chen. “It’s about understanding the boundaries of infectious diseases and preparing for the unexpected.”
FAQ: Understanding Chronic Wasting Disease and Prions
What is chronic wasting disease?
CWD is a fatal neurological disorder affecting deer, elk, and moose, caused by misfolded proteins called prions. Symptoms include weight loss, behavioral changes, and eventual death.
Can CWD infect humans?
No confirmed cases exist, but the new study suggests a theoretical risk under specific conditions. The CDC advises against consuming meat from infected animals.
How is CWD spread?
The disease spreads through direct contact with bodily fluids or contaminated environments, such as soil and water. Prions are highly resilient and can persist in the environment for years.
For now, researchers urge caution and continued monitoring. “We’re not facing an epidemic,” said Dr. Reynolds. “But we’re learning that the lines between species are not as rigid as we once believed.”