Introduction

For more than two decades, chronic wasting disease has been explained to hunters one way: a misfolded protein called a prion is the infectious agent, full stop. On a recent episode of the Drop-Tine Podcast, certified wildlife biologist Jason Snavely sat down with Dr. Laura Manuelidis, a Yale neuropathologist who has spent over five decades studying transmissible spongiform encephalopathies, to ask the question almost nobody in the hunting world hears out loud: what if the prion protein isn’t the infectious agent at all, but a footprint left behind by something else? What follows isn’t a debate about semantics. It’s a look at decades of data that never fit neatly into the story most hunters have been told.

Twenty-Five Years of Watching the Same Play Get Called

Jason opens the episode with a confession. After 25 years working alongside private and corporate wildlife management programs, he says he has never met a true CWD expert, including the popular podcast hosts and state agency biologists who play that role for hunters. His frustration isn’t personal. It’s that most of the people explaining CWD to the public have never run a transmission study, never worked with infectivity assays, and never had to defend original research on a TSE in front of their peers.

That frustration is what led him to Dr. Manuelidis. Her lab is one of the only labs in the country that actually studies infectivity itself, not just prevalence data and radio collar tracking.

Meet Dr. Laura Manuelidis

Dr. Manuelidis is a full professor of neuropathology at Yale University, where she has spent decades researching transmissible spongiform encephalopathies, including Creutzfeldt-Jakob disease, alongside separate work on DNA and chromosomes. Her research has been funded in large part by the National Institutes of Health. This episode marked her first appearance on any podcast, a detail that says as much about the state of the CWD conversation as anything discussed in the episode itself.

The Prion Theory, In Plain Language

In 1982, Dr. Stanley Prusiner proposed that a misfolded, infectious protein, which he named a prion, was the agent behind scrapie and related diseases. The idea was considered revolutionary because it broke from every known category of infectious agent: not a virus, not a bacterium, not a parasite. Prusiner won the Nobel Prize for the theory in 1997, and it has become the accepted explanation for CWD in deer and elk ever since.

Dr. Manuelidis doesn’t dispute that a misfolded protein exists. She agrees it does. What she disputes is the leap from “this protein shows up during infection” to “this protein is the cause of the infection.” In her words during the episode, the protein is better understood as a normal host protein that becomes amyloid once an animal is already infected, a marker left behind, not the agent that started the fire.

Data Against The Prion As The Infectious Agent (This is important!)

The key experiments from the past, that have been excluded from much of the modern day science, show that when you remove the normal host prions (PrP), infectivity is maintained!  If infection is still present in the absence of prions, you can’t point to the prions as the infectious agent! This is worth repeating!… Prusiner’s camp claims that the normal host protein becomes misfolded and represents the INFECTIOUS AGENT. However, all of the work done in Dr. Manuelidis’ lab at Yale show that when you DESTROY all forms of the normal host protein (PrP), INFECTIVITY IS MAINTAINED! If the normal host protein that becomes misfolded is the infectious agent, removing all forms of that normal host protein would remove infectivity; IT DOES NOT!  Why don’t we hear about these data from Manuelidis’ lab? Because it doesn’t fit the prion narrative!

The Nucleic Acid Debate

Prusiner’s prion camp also focuses on selling us this notion that prions don’t have any nucleic acids yet they are infectious.  In fact, prions don’t need to have any nucleic acids because experiments don’t prove them to be the infectious agent! Further, research has shown that when you destroy all nucleic acids, you lose 3 logs of infectivity; that is you lose 1,000 fold, or only have 1 part in a thousand left for infection.  This proves that nucleic acids are in fact present and involved in infectivity but no one is looking at this. Why? Because it doesn’t fit the prion narrative.  Data that the Prusiner prion camp exclude show that nucleic acids are in fact present and they are likely involved in infectivity. The data show that Scrapie and CWD require agent-associated nucleic acids for infection.

The Slow Virus Alternative

A Distinction First Made in Iceland

Long before Prusiner’s theory took hold, a researcher named Bjorn Sigurdsson was studying two sheep diseases in Iceland. One, visna, moved fast, behaved like an RNA virus, and later became a prototype for how scientists would eventually understand HIV. The other, scrapie, moved slowly. Sigurdsson called it a latent virus, one that could sit inside an animal’s cells for years, largely invisible to the immune system’s antibodies, before ever producing symptoms.

That slow virus framework was the accepted scientific language for these diseases for decades, long before the word “prion” entered the picture.

Evidence That Behaves Like a Virus, Not a Misfolded Protein

Dr. Manuelidis pointed to three lines of evidence her lab has documented. First, the infectious agent changes its replication speed depending on where it lives. Inside a living animal, protected by the immune system, it can take around ten days to double. Move that same agent into a tissue culture outside the animal, and it can double in about 24 hours, a behavior consistent with something that replicates, not a protein that simply misfolds.

Second, the agent carries a strain-specific identity that survives the jump between species, regardless of the host’s own prion protein. Move an infected sample from a hamster into a mouse, and the prion protein detected takes on the mouse’s own genetic signature almost immediately. But the underlying agent’s strain characteristics stay consistent across that jump. A misfolded protein alone shouldn’t be able to do that.

Third, actual virus-like particles have shown up in infected tissue since the 1970s, including images captured inside Prusiner’s own lab that were later set aside. Those particles have never appeared in uninfected tissue.

The Twenty Thousand Experiments Nobody Talks About

One of the more striking moments in the episode is Dr. Manuelidis’ reference to the work of researcher John Collins, a strong believer in the prion theory with the funding to run large-scale infectivity assays. According to her account, Collins has run roughly 20,000 experiments attempting to show that misfolded, lab-made prion protein alone is reproducibly infectious. None of them have succeeded. The signal shows up briefly in an early passage and then fades, rather than sustaining and spreading the way a true infectious agent would.

Size Matters!

The infectious agent has virus-like particles that are 20 to 25 Nanometers in diameter, which happens to be a common size for viruses.

Why This Isn’t Just an Academic Argument

If CWD behaves like a slow virus contained by an animal’s innate immune system, that has real implications for how the disease is detected and managed. Right now, most testing looks for misfolded prion protein in lymph tissue, which by Dr. Manuelidis’s account only shows up well after an infection has already taken hold. If a nucleic acid specific to the agent could be identified, animals could theoretically be tested at a much earlier stage, using something as simple as a blood sample, rather than relying on late-stage tissue markers after the fact.

It also reframes some of the herd management decisions built entirely around the prion model, including large-scale culling policies that Jason has long argued lack supporting data. Neither Jason nor Dr. Manuelidis claims to have the final answer here. Their point is narrower and, in some ways, more useful: the questions being asked about CWD may be starting from the wrong assumption entirely.

What This Means for Hunters and Land Managers Right Now

Nature runs on the same logic Dr. Manuelidis described in her lab. Genetics and overall immune health influence how long an infected animal can delay the onset of disease, sometimes by years. A stressed, nutritionally deficient herd has less capacity to keep a slow-moving infection contained. A herd with access to diverse, nutrient-dense forage, and low stress, is better positioned to support that natural immune defense in the first place.

That’s the same principle behind every blend in the Reload Series, built to support the biology of the herd rather than mask a problem after the fact. And just like Dr. Manuelidis’s lab measures what’s actually happening at the cellular level instead of guessing, the Haney Soil Test gives land managers a real read on their soil’s biological activity before the next planting window opens.

Key Takeaways

• The prion theory of CWD, first proposed in 1982, has never been independently replicated outside Dr. Stanley Prusiner’s own lab and its close scientific network.
• Dr. Laura Manuelidis, a Yale neuropathologist with over five decades of research on transmissible spongiform encephalopathies, argues the data fits a slow virus model first described in Iceland decades before the word “prion” existed.
• Slow viruses can remain latent inside cells for years, held in check by the innate immune system, before symptoms appear, a pattern also seen in diseases like tuberculosis.
• Roughly 20,000 infectivity experiments using lab-made misfolded prion protein have failed to reproducibly show that the protein alone causes infection.
• Evidence for a viral agent includes replication speed that changes with environment, strain-specific behavior that survives species transfer, and virus-like particles documented since the 1970s.
• If CWD behaves like a slow virus, earlier detection through blood-based testing could become possible, rather than relying solely on late-stage prion protein markers in lymph tissue.
• An animal’s overall immune health and genetics may influence how long it can delay the onset of disease, a variable that current herd management policy rarely accounts for.

Conclusion

None of this settles the current debate but instead points to what we’re missing and Dr. Manuelidis is careful to frame it that way herself. Her argument isn’t about belief, it’s about following data that have been set aside for decades and asking whether the field made a wrong turn somewhere along the way. Wildlife science moves forward by asking better questions, not by defending the same answers to the same questions for 40 years.

Hear the full conversation, including the lab slides Dr. Manuelidis walks through in detail, on the Drop-Tine Podcast YouTube channel. And if this conversation has you thinking harder about what a truly healthy herd needs to defend itself, that same philosophy, working with biology instead of guessing, is exactly what’s behind every acre we help you plant.

Frequently Asked Questions

What is the difference between the prion theory and the slow virus theory of CWD?

The prion theory holds that a misfolded normal host protein is itself the infectious agent that causes CWD. The slow virus theory, argued by Dr. Laura Manuelidis, holds that the misfolded protein is a marker left behind by an underlying viral infection, not the cause of it. Both models agree the misfolded protein exists. They disagree on what actually causes the disease process.

Who is Dr. Laura Manuelidis?

Dr. Manuelidis is a full professor of neuropathology at Yale University who has spent over five decades researching transmissible spongiform encephalopathies, including Creutzfeldt-Jakob disease and scrapie. Her research has been supported by the National Institutes of Health, and her appearance on the Drop-Tine Podcast was her first on any podcast.

Is chronic wasting disease definitely caused by a virus?

No. The slow virus hypothesis is a serious, data-supported alternative to the prion theory, but it hasn’t been proven any more definitively than the prion theory has. The honest answer, according to both Jason and Dr. Manuelidis, is that the infectious agent behind CWD is still an open scientific question. Perhaps the most important question; however, is: Why aren’t we focusing more on infectivity and searching for the true infectious agent? Many of the great, early studies can be replicated to further prove the slow virus hypothesis correct; where there’s smoke, there’s fire.

Does this change how hunters should think about CWD testing?

It doesn’t change what’s available to hunters today, since current testing looks for misfolded prion protein in lymph tissue. But it does suggest that earlier, blood-based detection methods could be possible in the future if the underlying agent turns out to be a virus with an identifiable nucleic acid.

Where can I watch the full podcast episode?

The full episode, including Dr. Manuelidis’s lab slides and a deeper walkthrough of the evidence, is available on the Drop-Tine Podcast YouTube channel.