Few discoveries in veterinary medicine have been as unsettling as bovine spongiform encephalopathy (BSE). The realization that a misfolded protein could behave like an infectious agent forced a total rethink of disease biology. Now, research from Goldansaz and colleagues at the University of Alberta suggests something even more unexpected: spongiform neurodegeneration may occur even when classical infectious prions cannot be detected.
Brain Damage Without Infection
To determine if brain damage can be triggered by noninfectious pathways, researchers compared five distinct treatment groups in a mouse model. By isolating the effects of systemic inflammation and laboratory-misfolded proteins, the study aimed to see if the hallmark infectious agent was truly a requirement for disease.
- LPS group — Chronic systemic inflammation via bacterial endotoxin.
- Res-PrP group — Exposure to a laboratory-produced, misfolded recombinant prion protein (structurally abnormal but noninfectious).
- RML group — A standard strain of infectious prions.
- Res-PrP + LPS — Combining noninfectious misfolded proteins with systemic inflammation.
- RML + LPS — Combining infectious prions with systemic inflammation.
The study’s results indicate that structural brain damage resembling prion disease is not exclusive to infectious transmission.
- Spongiform lesions — All treatment groups, including those exposed only to LPS or noninfectious Res-PrP, developed the tiny vacuoles that give brain tissue the sponge-like appearance typical of BSE.
- Astrogliosis — Animals exposed to the misfolded Res-PrP showed significant activation of supportive glial cells. This indicates that even in the absence of an infectious strain, “toxic” protein conformations are sufficient to trigger neuroinflammation and neuronal damage.
- Amyloid-beta deposition — In the chronic LPS-only group, researchers observed amyloid-beta plaques — a form of aggregation more common in other neurodegenerative disorders — suggesting that inflammatory stress alone can disrupt protein folding pathways.
Survival and Synergistic Toxicity
The survival data reinforces the idea that inflammation acts as a potent catalyst for these toxic pathways.
| Treatment Group | Mortality & Progression |
| LPS (inflammation only) | 10% mortality by 350 days; about 40% by 650 days |
| Res-PrP (noninfectious prion) | 20% mortality by 200 days; about 60% by 750 days |
| Res-PrP + LPS | 30% mortality by 150 days; about 50% by 750 days |
| RML (infectious prion) | 80% mortality by 200 days |
| RML + LPS | 30% mortality by 100 days; 100% by 200 days |
What Veterinarians Should Know
While these findings do not overturn the established cause of BSE outbreaks — contaminated feed remains the primary target for regulatory control — they do introduce three critical considerations for the future of veterinary neurology:
- Noninfectious toxicity — Misfolded prion proteins may be directly neurotoxic to the host even if they lack the ability to spread as an infectious “strain.”
- Inflammatory priming — Systemic inflammatory stress can initiate or amplify protein-misfolding pathways, potentially lowering the threshold for neurodegeneration.
- Etiology of atypical cases — These biological routes may help explain sporadic or “atypical” neurodegenerative cases that do not fit the standard infectious exposure model.
The discovery of prions once forced scientists to rethink the nature of infection. This research suggests we are still uncovering the diverse biological routes that lead to the same devastating neurological damage.
For the veterinary community, it highlights how systemic inflammation and protein misfolding pathways can interact to initiate or amplify prion-like pathology, even in the absence of an external infectious agent.
