Surveillance of wildlife diseases poses multiple challenges, including the availability of samples for testing and, in some situations, issues with suboptimal tissue condition. Chronic wasting disease (CWD) is a prion disease threatening the health of wild and captive cervids that is diagnosed with enzyme-linked immunosorbent assay (ELISA) and/or immunohistochemistry (IHC) of retropharyngeal lymph nodes or obex tissue. IHC uses the three-dimensional structure from fresh preserved tissues to facilitate the detection of accumulated prion proteins PrPCWD within the tissue architecture. ELISA does not require tissue structure and uses tissue lysates to detect PrPCWD, but its ability to detect PrPCWD in degraded diagnostic samples is unknown. We thus examined how lymph node decomposition at 4°C and 27°C for up to 12 months affects the ability of ELISA to detect CWD prions in known CWD-positive lymph nodes from wild white-tailed deer (Odocoileus virginianus) in Illinois, USA. We found that prions remained detectable in 100% of the lymph nodes decayed for 12 months at both temperatures, though the detection percentage in each experimental group varied over time. Our findings are the first to demonstrate that USDA-APHIS approved ELISA assays can be used on extensively degraded lymph nodes for CWD surveillance, enabling testing of tissue in suboptimal conditions using.
Managing chronic wasting disease (CWD) - a fatal, transmissible prion disease of cervids - has many challenges, such as determining the number of cervids to test to accurately estimate true prevalence with apparent prevalence. Options range from basic equations to complex techniques like agent-based modelling, but the former does not account for parameter uncertainty, and more detailed models may be less accessible for managers. Our study used Monte Carlo simulation to create a reference table showing the number of hunter-harvested deer to test to approximate herd true prevalence with a ± 2% margin of error and 95% confidence. A three-step process was simulated in which deer from the total population were harvested (testable subpopulation), and then a subset of those harvested deer were tested for CWD (tested group) with diagnostic testing error, with group assignment determined by random sampling. We evaluated true prevalences ranging from 0.5-20% and testable subpopulation sizes up to 5,000 deer from a total population of 20,000. An example from the reference table shows that detecting a 1% true prevalence in a testable subpopulation of 300 deer requires testing ≥280 deer, and that the only way to accurately detect a true prevalence of 0.5% is to test 600 out of 5,000 deer. Evaluating IDNR's CWD surveillance efforts found that 16.14% of counties had adequate sample sizes in a given year and could detect true prevalences as low as 1%, showing that these guidelines are achievable.
Prion diseases are fatal neurodegenerative disorders characterized by abnormally folded prion proteins inducing misfolding of normal prion proteins, leading to neurotoxic fibrils and plaques. Epigenetic mechanisms, particularly DNA methylation, are increasingly implicated in prion-like diseases (e.g. Alzheimer's disease), but their role in prion pathogenesis remains unclear. To investigate, we used nanopore sequencing and RNAseq to measure genome-wide methylation and gene expression in the brains of Syrian hamsters (Mesocricetus auratus) experimentally infected with a hamster-adapted murine synthetic prion strain (n = 9) and age-matched mock-infected controls (n = 9) at 80, 120, and 160 days post-infection (dpi). We identified 1,586, 1,692, and 2,429 differentially methylated regions (DMRs) at 80, 120, and 160 dpi, respectively. Early- and mid-stage prion disease (80 and 120 dpi) skewed towards hypermethylation, whereas late-stage prion disease (160 dpi) skewed towards hypomethylation. Gene ontology (GO) of DMR-associated genes at 160 dpi included neuron regulation and signalling, neurodevelopment, and cellular stress pathways. We identified 178 differentially expressed genes (DEGs) at 80 dpi, 90 at 120 dpi, and 616 at 160 dpi. The majority of DEGs were downregulated at 80 dpi, and at 120 and 160 dpi, most were upregulated. Overlap in DEGs across timepoints was limited, and GO terms were related to upregulation of disease/injury response and cell death pathways in later timepoints. Overall, we found a stage-specific transcriptional shift from immune suppression to widespread immune and inflammation activation. These findings provide time-resolved data on methylation and transcriptional changes associated with impaired neuronal structure, function, and communication during disease.
Sporadic Creutzfeldt-Jakob disease (sCJD) is a rare, rapidly progressive, and fatal neurodegenerative disorder caused by the accumulation of abnormal prion proteins in the central nervous system. The Heidenhain variant (HvCJD), a rare subtype of sCJD, is characterized by prominent visual symptoms at onset. Diagnosing sCJD remains challenging due to non-specific clinical presentations and the limited sensitivity and specificity of conventional tests such as magnetic resonance imaging (MRI), electroencephalography (EEG), and cerebrospinal fluid (CSF) 14-3-3 protein analysis. Recently, real-time quaking-induced conversion (RT-QuIC) has emerged as a valuable tool for improving diagnostic accuracy. We present the case of a 65-year-old man who initially experienced blurred vision and diplopia, followed by rapidly progressive dementia and dysuria. Brain MRI revealed cortical diffusion-weighted imaging (DWI) hyperintensities in the right temporo-occipital region. While his CSF 14-3-3 protein test was negative, RT-QuIC assay returned positive, leading to a final diagnosis of probable CJD. The patient died 8 weeks after diagnosis. This case highlights that HvCJD is a rare but important clinical variant in which conventional CSF 14-3-3 testing may be negative, particularly early in the disease course. In contrast, RT-QuIC demonstrates high sensitivity and specificity and can significantly aid in the early and accurate diagnosis of CJD.
In memoriam of Pawel P. Liberski, an enthusiastic scientist of rare intelligence, a loyal and generous friend, and a truly vivid personality.
Chronic wasting disease (CWD) is a fatal neurodegenerative prion disease of cervids that can be transmitted through direct physical contact, indirect contact with a contaminated environment, or vertical transmission. CWD is characterized by a long incubation period followed by symptoms like loss of appetite resulting from the destruction of brain tissue. While the consequences for infected animals are clear, a previous study from our laboratory showing lower body weights in the foetuses of CWD-positive female deer suggests those consequences may be intergenerational. In this study, we addressed the impact of maternal CWD infection on foetal head development (as a proxy for brain growth) in wild white-tailed deer using data from CWD management efforts in northern Illinois, U.S.A. Multivariate, multilevel, Bayesian Gamma regression found that maternal CWD infection reduced foetal head nose-occipital length and crown-jaw circumference by 6.76% and frontal-occipital length by 11.31%. These findings suggest impeded brain development in the offspring of CWD-infected female deer, which could reduce fawns’ survival and success after birth and lead to a decline in population fitness over time. This study is the first to demonstrate the detrimental effects of a prion disease on foetal brain development in any animal species regardless of whether vertical transmission has occurred.
Clinicopathologically, dura mater graft-associated Creutzfeldt-Jakob disease (dCJD) presents as either a non-plaque or plaque type. Here, we report an autopsy case of plaque-type dCJD, supported by genetic and biochemical analyses. A 41-year-old man manifested right-hand paraesthesia. He had received a dural graft in the right parietal region following a traumatic acute subdural haematoma 27 years before symptom onset. The clinical course was slowly progressive. The patient became unable to walk independently 17 months after onset, showed cognitive decline at 22 months, and developed myoclonus and akinetic mutism at 24 months. Periodic sharp-wave complexes were never observed on electroencephalography throughout the disease course. He died 26 months after symptom onset. No mutations were identified in the prion protein (PrP) gene, and the codon 129 polymorphism was homozygous for methionine. Neuropathologically, mild to moderate spongiform changes with fine vacuoles, neuronal loss, and astrogliosis were observed in the brain and spinal cord. Degeneration was relatively severe in the limbic system, striatum, thalamus, and cerebellum, resembling the distribution pattern of VV2 sporadic CJD. Abnormal PrP deposition was broadly distributed consisting of synaptic, perineuronal, and plaque forms. In particular, intense PrP staining was observed throughout the spinal grey matter. Western blotting detected intermediate-type PrP in the brain and cervical cord, but not in systemic organs. Considering the clinical course and PrP staining in the spinal cord, PrP transmission is suggested to occur not directly from the transplanted dura mater to the central nervous system, but rather indirectly via a peripheral route.
Mutations in superoxide dismutase 1 (SOD1) cause paralysis in familial amyotrophic lateral sclerosis and promote its misfolding into neurotoxic aggregates. Previous studies have shown that mice expressing the ALS-causing G85R variant of SOD1 develop paralysis much faster after intraspinal injection of spinal homogenates from paralysed G85R SOD1 mice. These findings, and other studies in cell models, established the prionoid templating properties of misfolded mutant SOD1. Previously, however, we noted that the widely used Gur1-G93A SOD1 mice, which express at high levels and develop paralysis by 6 months of age, were resistant to seeding by homogenates from paralysed G93A mice. A line of G93A mice that expresses at very low levels (VLE-G93A) was responsive to seeding but at low efficiency. The poor susceptibility of G93A-SOD1 mice to seeding was not what we expected if prion-like propagation is essential to SOD1 ALS pathogenesis. In our prior studies, seeding homogenates from paralysed G93A-SOD1 mice were injected into the spine of newborn mice, leading us to question whether older G93A SOD1 mice might be more susceptible to seeding. Here, we establish that adult VLE G93A SOD1 mice (up to 12 months of age) injected intrathecally with seeding homogenates containing misfolded G93A or G85R SOD1 developed accelerated motor neuron disease efficiently. Thus, we demonstrate that both the route and age of inoculation can influence the efficiency of SOD1 seeding to induce motor neuron disease in VLE G93A-SOD1 mice. These data, together with our earlier reports, suggest that prion-like templating contributes to disease progression in SOD1-ALS.
Prion 2025, held in Armação dos Búzios, Brazil (3-7 November 2025), was the first PRION congress in Latin America and brought together 260 participants from 22 countries. Building on the broadening scope of recent meetings, this edition placed the cellular prion protein (PrP) back at centre stage while maintaining a strong focus on prion-like mechanisms and functional amyloids. Clinical and epidemiological sessions addressed rapidly progressive dementias and prion and prion-like diseases, underscoring the need for structured diagnostic pathways and closer interaction between surveillance networks and specialized centres. Basic science sessions explored PrP biology, with an emphasis on liquid - liquid-phase separation, early misfolding events, and structural features that underpin prion propagation and strain diversity. The programme also dedicated space to emerging diagnostics and biomarkers, as well as to therapeutic strategies, including PrP-lowering approaches and targeting proteostasis and cellular clearance pathways. Sessions on yeast, bacterial, and memory amyloids broadened the discussion to functional and evolutionary aspects of amyloid formation. Finally, Prion 2025 strengthened engagement with patient organizations and families, incorporating dedicated panels and family-oriented activities into the programme. Overall, the meeting reinforced links between basic and translational prion research and placed patients' and families' perspectives at the heart of the discussion.
Infectious prions (PrPSc) are largely resistant to proteolytic digestion, including proteinase K (PK) digestion. While nucleic acid extracts are generally considered non-infectious from a classical microbiology context (i.e. free of intact bacteria and viruses), we investigated whether standard DNA purification methods co-purify PrPSc, posing an unrecognized biosafety risk. Commercial DNA extraction kits can eliminate conventional pathogens but are likely ineffective against PrPSc due to resistance to kit reagents and enzymatic degradation. Two laboratories, the University of Minnesota Center for Prion Research and Outreach (MNPRO) and the Canadian Food Inspection Agency (CFIA), independently tested filter-based and magnetic bead-based DNA extraction kits using tissues from chronic wasting disease (CWD)-positive and -negative white-tailed deer (WTD; Odocoileus virginianus), as well as prion-infected and control Syrian hamster (Mesocricetus auratus) brains. CFIA used two filter-based kits (one automated, one manual), while MNPRO tested two manual kits (filter- and magnetic bead-based). PrPSc seeding activity was measured in extracted DNA and source tissues using real-time quaking-induced conversion (RT-QuIC). MNPRO found substantial to almost perfect agreement between RT-QuIC seeding activity of DNA eluates from both extraction methods and that of the source WTD tissue homogenate. CFIA optimized RT-QuIC to a 30-hour runtime, achieving 74% sensitivity and 94% specificity in 88 archived WTD DNA samples. Both laboratories concluded that commercial DNA extraction kits do not eliminate PrPSc, enabling carry-over into DNA eluates. Until infectivity is resolved by animal bioassay, DNA from PrPSc-positive tissues should be handled under biosafety protocols appropriate for the originating prion disease, with decontamination and containment procedures.
Background The prion diseases (PrD) are a group of progressive, fatal, neurodegenerative diseases, for which the Medical Research Council Prion Disease Rating Scale (MRC Scale) can be used to assess patients’ functional deterioration. Findings from previous qualitative interviews with caregivers and clinical experts identified potential ambiguities in the scale that could lead to inconsistent scoring within and/or between raters.Methods A draft User Guide was developed based on findings from a previous qualitative study. The draft included clarifications regarding domain wording, scoring levels, and guidance for response option selection. Five clinical experts with PrD management experience provided written feedback on the draft User Guide, which was incorporated into a revised User Guide. A 90-minute consensus meeting was then held with these experts to confirm the final content to be included in the User Guide.Results The final User Guide was designed to accompany the MRC Scale and assist with rater decisions related to which response option most accurately describes a patient’s health status. Conclusions: The User Guide is expected to be a valuable complement to the MRC Scale, which is poised to rise in use and prominence as global clinical research efforts accelerate to address the significant unmet need of PrD patients.
Gerstmann - Sträussler - Scheinker disease (GSS) is a hereditary prion disease characterized by clinicopathological heterogeneity. In Japan, the most common mutation is P102L, typically associated with prion protein (PrP) plaques, spongiform changes, and synaptic PrP deposits. Two major protease-resistant PrP (PrPres) types occur: type-1 PrPres (21 kDa) and 8-kDa PrPres. The PRNP codon 129 polymorphism (methionine or valine) influences disease phenotype, but factors underlying exclusive 8-kDa PrPres expression remain unclear. We analysed two sibling P102L GSS cases exclusively exhibiting 8-kDa PrPres (Case 1: 129 MM, haplotype: P102L-129 M, treated with pentosan polysulfate; Case 2: 129 MV, haplotype: P102L-129 M, treated with quinacrine hydrochloride and quinine hydrochloride) and four P102L-129 MM GSS cases exhibiting type-1 and 8-kDa PrPres (Cases 3-6) to elucidate the clinicopathological effect of 8-kDa PrPres and PRNP codon 129 polymorphisms. Case 1 predominantly exhibited amyloidogenic PrP plaques; Case 2 exhibited non-amyloidogenic cotton-wool PrP plaques, with minimal synaptic PrP deposits. Despite prolonged survival ( > 20 years), spongiform degeneration and neuronal loss were mild. Cases 3-6 showed numerous amyloidogenic PrP plaques, moderate-to-severe synaptic PrP deposits, and significant tissue damage. Homoeostatic microglial markers were preserved in Cases 1 and 2 but absent in Cases 3-6. Cotton-wool PrP plaques lacked amyloid cores and were associated with 8-kDa PrPres and codon 129 V from the normal allele. Tissue damage was mild in P102L GSS cases exhibiting 8-kDa PrPres, suggesting lower pathogenicity. Cotton-wool PrP plaque formation likely involves 8-kDa PrPres and codon 129 V. Further large-scale studies are warranted to elucidate these mechanisms.
Bovine Spongiform Encephalopathy (BSE) is a fatal neurodegenerative disease in cattle which can be either classical BSE (C-BSE) or atypical BSE (including H-BSE and L-BSE). Here, we report the results of our analyses of an H-BSE case found in Canada in 2021, indicating restriction of the pathological agent (PrPSc) mainly to the central nervous system with no or occasional weak involvement of peripheral tissues. Importantly, a non-synonymous mutation at codon 211 of the PRNP gene was detected and confirmed to be present as a germline mutation. This is the first case of BSE in Canada with a predisposing E211K mutation.
Chronic wasting disease (CWD) is a fatal, neurodegenerative disease of cervids, and its management heavily relies on diagnostic testing. Test results are commonly used to calculate 'apparent prevalence' (AP) - the percent of animals tested for CWD (CWD tests) with CWD-positive test results (CWD cases) - but this obscures how tests and cases individually contribute to this statistic. This is most relevant when CWD testing is limited because when few animals are tested, detection of even a single infected deer can result in a high AP that poorly reflects reality. We hypothesized that when CWD testing is limited, AP is negatively driven by testing - rather than cases - with more tests corresponding to lower APs. Graphed CWD surveillance data from townships in Illinois and Wisconsin, USA, indicate that CWD AP values ≥50% were only observed when <23 deer were tested. We used Bayesian multilevel zero-inflated Beta regression to model AP as a function of CWD tests, CWD cases and nonlinear transformations of these two terms separately for each state. The best-fit models of both identified a statistically significant negative relationship between AP and testing numbers that was modified by a positive nonlinear test covariate. This means adding tests when testing is low can have a big impact on decreasing the AP, but this relationship weakens as testing increases. We urge treating apparent prevalences ≥50% with caution and emphasize the importance of increasing the test results when initial surveillance has yielded <23 tests.
Chronic wasting disease (CWD) is a highly contagious prion disease occurring in free-ranging and farmed cervids. In the Republic of Korea, cases of CWD continue to be detected almost annually, on both new and occasionally previously infected farms. CWD-infected animals contaminate soil and other environmental components by shedding prions through their excreta. Since shed prions remain infectious for years in the environment, they can act as infectivity reservoirs facilitating horizontal transmission of CWD. To prevent the further spread of CWD and allow farms to resume operations, control measures on infected farms, including topsoil removal and thorough environmental treatment with 2N NaOH, have been implemented in the Republic of Korea. Restocking remediated farms with cervids was permitted after confirming the absence of prion seeding activity in soil samples using protein misfolding cyclic amplification (PMCA). A total of 215 samples from 18 remediated farms were collected and analysed using PMCA, with only 3 samples from 3 farms displaying prion seeding activity. While the disease control measures effectively eliminated prion seeding activity in CWD-affected farms, CWD recurred at two of the 18 remediated farms 4 to 5 years after restocking animals. It remains unclear whether the recurrence of CWD at the two farms was due to residual prions in the environment after the control measures, or the introduction of the infected animals from other farms. This uncertainty is heightened by the annual occurrence of CWD at multiple farms and the absence of a traceability system for farmed cervids.
Chronic wasting disease (CWD) is a contagious prion disorder affecting cervids such as deer, elk, caribou, and moose, causing progressive and severe neurological degeneration followed by eventual death. As CWD prions (PrPSc) accumulate in the body, they are shed through excreta and secreta, as well as through decomposing carcasses. Prions can persist in the environment for years, posing significant concerns for ongoing transmission to susceptible cervids and pose an unknown risk to sympatric species. We used a validated protocol for real-time quaking-induced conversion (RT-QuIC) in vitro prion amplification assay to detect prions in soil collected within and around an illegal white-tailed deer (Odocoileus virginianus, WTD) carcass disposal site and associated captive WTD farm in Beltrami County, Minnesota. We detected PrPSc in 26 of 201 soil samples across 15 locations within the illegal disposal site and one on the farm that housed the cervids. Importantly, a subset of RT-QuIC positive soil samples was collected from soils where carcasses were recovered, providing direct evidence that environmental contamination resulted from this illegal activity. These findings reveal that improper cervid carcass disposal practices may have important implications for ongoing CWD transmission through the environment.
The Prion 2024 annual conference, held in Nanchang, China, from 23 to 27 October, drew nearly 300 leading scientists, clinicians, researchers, and students from 17 countries to examine the latest advancements in prion research and related diseases. This landmark event marked the inaugural international prion conference hosted in a developing nation for the first time and celebrated the 20th anniversary of the NeuroPrion Association, the organizing body of this prestigious annual gathering - 'Celebrating Two Decades of Progress: Pioneering a New Era.' The conference spotlighted key themes such as epidemiology, pathogenesis, the connections between ageing and neurodegenerative diseases. It showcased innovative diagnostic and therapeutic strategies for both human and animal prion diseases, as well as related conditions including Alzheimer's and Parkinson's diseases, prion protein-associated cancers, and renal injury. The programme featured 70 invited talks and 21 selected oral presentations, culminating in 7 plenary sessions led by esteemed speakers, including Nobel Laureate Stanley B. Prusiner. This overview summarizes key presentations and highlights significant aspects of the conference, emphasizing the impactful discussions and collaborations that emerged from this historic event.
Prion diseases, also known as transmissible spongiform encephalopathies (TSEs), are fatal neurodegenerative disorders that result from abnormally folded prion proteins. These disorders can be sporadic, acquired, or genetic. Acquired TSEs can be found in a number of animal species including sheep (scrapie), cows (bovine spongiform encephalopathy), and cervids (chronic wasting disease). Chronic wasting disease (CWD) is unusual in that it is found in free ranging animals in their natural environment. There has been heretofore no reported cases of CWD being transmitted to humans; however, the possibility of future adaption for human transmission exists. Several novel approaches for the prevention and treatment of prion disease in humans are under development, including knockdown of endogenous prion expression or overexpression of dominant negative prion forms. Here, I propose that CWD, as a naturally occurring prion disease, should be considered an important testing target for such therapies, which can demonstrate efficacy outside of controlled laboratory environments. Further, from the ethical standpoint of reducing animal suffering, decreasing the CWD burden in cervid populations is highly desirable. Finally, lowering CWD incidence can reduce future possibilities of transmission to humans or to other animal species.
The FXR1 protein regulates the stability and translation of a number of RNA molecules and plays an important role in the regulation of cellular processes under normal conditions and stress. In particular, this protein is known to be a negative regulator of the key proinflammatory cytokine TNF alpha. We had previously shown that FXR1 functioned in the amyloid form in neurons of the brain of jawed vertebrates. Under stress conditions, FXR1 is incorporated into stress granules in some cell lines, but such studies have not been conducted for neuronal cells. Here, we showed the ability of the FXR1 protein to form cytoplasmic granules in a neuroblastoma cell line under various types of stress. This protein colocalizes with core proteins of neuronal stress granules upon heat shock and sodium arsenite treatment. We also showed that FXR1 colocalizes with anti-amyloid antibodies OC under both normal and stress conditions. Given that stress granules are dynamic structures, we propose that amyloid FXR1-containing RNP particles interact with other stress granule proteins through weak intermolecular hydrogen bonds. Using a yeast model system, we found that FXR1 colocalizes and physically interacts with stress granule proteins such as TIA-1, FMRP, FXR2, and SFPQ. Overall, our results provide new insights into the role of the RNA-binding protein FXR1 in neuronal stress response. We believe that FXR1 inactivation in neuronal stress granules can contribute to an increase in the level of the proinflammatory cytokine TNF alpha in neurodegenerative diseases.
An early diagnosis is required for intervention in prion disease cases. To elucidate the specificity of early electroencephalography discharges in cases of sporadic Creutzfeldt-Jakob disease, we analysed epileptiform discharges through electroencephalography. Nine patients with methionine/methionine type 1/classic sporadic Creutzfeldt-Jakob disease and 20 patients with status epilepticus were included. Generalized periodic discharges, lateralized periodic discharges, and central sagittal sporadic epileptiform discharges were evaluated. Central sagittal sporadic epileptiform discharges were defined as nonrhythmic and nonperiodic waveforms showing generalized spike-and-wave complexes and/or sharp waves predominantly in the central sagittal region. In the sporadic Creutzfeldt-Jakob disease group, central sagittal sporadic epileptiform discharges, lateralized periodic discharges, and generalized periodic discharges were observed in five (55.6%), one (11.1%), and eight (88.9%) patients, respectively, with an average duration from onset to the appearance of the discharges of 1.6, 1.0, and 2.44 months, respectively. In the status epilepticus group, these discharges were detected in one (5.0%), six (30.0%), and six (30.0%) patients, respectively. The incorporation of central sagittal sporadic epileptiform discharges and lateralized periodic discharges into the World Health Organization diagnostic criteria, alongside generalized periodic discharges, significantly shortened the average lapse from symptom onset to sporadic Creutzfeldt-Jakob disease diagnosis (2.06 months vs. 2.44 months; p = 0.02). Central sagittal sporadic epileptiform discharges emerge as promising biomarkers for distinguishing sporadic Creutzfeldt-Jakob disease from status epilepticus, and together with lateralized periodic discharges provide an opportunity for early diagnosis of sporadic Creutzfeldt-Jakob disease.
