Jason C Bartz

Infectious prions (PrP ) 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 PrP , posing an unrecognized biosafety risk. Commercial DNA extraction kits can eliminate conventional pathogens but are likely ineffective against PrP 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; ), as well as prion-infected and control Syrian hamster ( ) brains. CFIA used two filter-based kits (one automated, one manual), while MNPRO tested two manual kits (filter- and magnetic bead-based). PrP 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 PrP , enabling carry-over into DNA eluates. Until infectivity is resolved by animal bioassay, DNA from PrP -positive tissues should be handled under biosafety protocols appropriate for the originating prion disease, with decontamination and containment procedures.

The role of the Common Vampire Bat (Desmodus rotundus) as a vector for chronic wasting disease (CWD) remains uninvestigated, and the effects of prion exposure in vampire bats are unknown. Desmodus feeds on the blood of various animals including deer, livestock, and humans across its expansive distribution. Given the continued southward spread of CWD in North American cervid populations and potential for the disease to already be circulating in Mexico, where it may overlap with established Desmodus populations, it is critical to assess potential risks at the interface between vampire bats and prion-infected hosts. Desmodus is also predicted to expand its range northward, potentially establishing populations in CWD-endemic regions of the southern United States, further underscoring the need for proactive surveillance and research on the ecological and epidemiological implications of this emerging interface. We explore aspects of prion biology and the natural history of Desmodus, highlighting factors that may contribute to prion exposure events among vampire bats and sympatric mammals. In light of Desmodus feeding behaviors, vampire bats could experience elevated prion exposures over time if they encounter CWD-positive prey. We recommend risk assessments and surveillance to evaluate vampire bat-prion transmission pathways that could impact mammalian wildlife, livestock, and human health. Chronic wasting disease (CWD), a fatal prion disease of cervids, is rapidly expanding across North America and may already be circulating in northern Mexico. Vampire bats are predicted to overlap with CWD-positive deer populations; thus, their feeding behavior raises the possibility of prion exposure and novel prion transmission pathways. This emerging interface underscores the need for targeted surveillance and risk assessment to evaluate potential impacts on wildlife, livestock, and public health. ResumenEl papel del vampiro com & uacute;n (Desmodus rotundus) como vector de la Enfermedad de desgaste cr & oacute;nico (CWD, por sus siglas en ingl & eacute;s) sigue sin ser investigado y se desconocen los efectos de la exposici & oacute;n a priones en murci & eacute;lagos vampiro. Desmodus se alimenta de la sangre de diversos animales incluidos ciervos, ganado y humanos a lo largo de su amplia distribuci & oacute;n. Dada la continua propagaci & oacute;n de la CWD hacia el sur en las poblaciones de c & eacute;rvidos de Am & eacute;rica del Norte y la posibilidad de que la enfermedad ya est & eacute; circulando en M & eacute;xico, donde podr & iacute;a superponerse a las poblaciones establecidas de Desmodus, es fundamental evaluar los riesgos potenciales en la interfaz entre murci & eacute;lagos vampiro y hospedadores infectados con priones. Se prev & eacute; tambi & eacute;n que Desmodus expanda su rango de distribuci & oacute;n hacia el norte, posiblemente estableciendo poblaciones en regiones del sur de Estados Unidos donde la CWD es end & eacute;mica, lo que resalta la necesidad de vigilancia proactiva e investigaci & oacute;n sobre las implicaciones ecol & oacute;gicas y epidemiol & oacute;gicas de esta interfaz emergente. Exploramos aspectos de la biolog & iacute;a de los priones y la historia natural de Desmodus, destacando los factores que pueden contribuir a eventos de exposici & oacute;n a priones entre los murci & eacute;lagos vampiro y los mam & iacute;feros simp & aacute;tricos. Considerando los h & aacute;bitos alimenticios de Desmodus, los murci & eacute;lagos vampiro podr & iacute;an experimentar exposiciones elevadas a priones si se alimentan de presas positivas para CWD. Recomendamos realizar an & aacute;lisis de riesgo y vigilancia para evaluar las posibles v & iacute;as de transmisi & oacute;n murci & eacute;lago vampiro-prion que podr & iacute;an afectar a mam & iacute;feros silvestres, al ganado y a la salud humana.

Prion diseases are fatal neurodegenerative disorders with no approved therapies that halt or reverse disease progression. Given that cellular prion protein (PrP C ) expression is required for prion propagation and neurotoxicity, reducing its expression is a promising therapeutic strategy. However, complete PrP ablation, as seen in knockout models, causes subtle developmental and behavioral abnormalities, raising concerns about long-term safety. Here, we explore a complementary strategy that harnesses the dominant-negative effect of the naturally protective G127V PrP variant found in kuru-resistant individuals in Papua New Guinea. In CAD5 cell lines, we demonstrate that inducible expression of G126V PrP (the mouse equivalent of human G127V) along with WT PrP prevents and suppresses prion infection in a dose-dependent manner. Extending this approach to CAD5 cells that express bank vole PrP, we further show that the protective effect of G127V spans a wide range of naturally and artificially derived prion strains, highlighting the generality of the dominant-negative approach. Remarkably, prion resistance persists even after G126V expression had ceased, indicating a sustained protective effect that could obviate the need for continuous transgene expression in a therapeutic setting. Finally, we find that anchorless, recombinant G127V PrP retains a potent dominant-negative activity, suggesting the use of this protein as a biological therapeutic. Together, these findings define a framework for development of G127V, a naturally protective and evolutionarily selected PrP variant, as a therapeutic agent to treat or prevent prion diseases.Prion diseases are fatal neurodegenerative disorders with no approved therapies that halt or reverse disease progression. Given that cellular prion protein (PrP C ) expression is required for prion propagation and neurotoxicity, reducing its expression is a promising therapeutic strategy. However, complete PrP ablation, as seen in knockout models, causes subtle developmental and behavioral abnormalities, raising concerns about long-term safety. Here, we explore a complementary strategy that harnesses the dominant-negative effect of the naturally protective G127V PrP variant found in kuru-resistant individuals in Papua New Guinea. In CAD5 cell lines, we demonstrate that inducible expression of G126V PrP (the mouse equivalent of human G127V) along with WT PrP prevents and suppresses prion infection in a dose-dependent manner. Extending this approach to CAD5 cells that express bank vole PrP, we further show that the protective effect of G127V spans a wide range of naturally and artificially derived prion strains, highlighting the generality of the dominant-negative approach. Remarkably, prion resistance persists even after G126V expression had ceased, indicating a sustained protective effect that could obviate the need for continuous transgene expression in a therapeutic setting. Finally, we find that anchorless, recombinant G127V PrP retains a potent dominant-negative activity, suggesting the use of this protein as a biological therapeutic. Together, these findings define a framework for development of G127V, a naturally protective and evolutionarily selected PrP variant, as a therapeutic agent to treat or prevent prion diseases.

In synucleinopathies, the protein α-synuclein misfolds into Lewy bodies (LBs) in patients with Lewy body disease (LBD) or into glial cytoplasmic inclusions (GCIs) in patients with multiple system atrophy (MSA). The ability of a single misfolded protein to cause disparate diseases is explained by the prion strain hypothesis, which argues that protein conformation is a major determinant of disease. We recently reported the unexpected finding of a novel α-synuclein strain in a Parkinson’s disease with dementia patient sample containing GCI-like co-pathology along with widespread LB pathology, which led us to question if two α-synuclein strains can interact with one another in a patient and, if so, can strain competition occur. To test this possibility, we used the strain interference model developed in the prion field, in which a slower replicating strain—in this study, mouse-passaged MSA—is used to compete with a faster replicating strain—here, recombinant preformed fibrils (PFFs)—following sciatic nerve (sc.n.) inoculation. Unexpectedly, we found that PFFs generated using the same method differed in their ability to neuroinvade following sc.n. inoculation based on α-synuclein monomer source. Using a PFF preparation that does spread from the periphery, we conducted strain competition studies by first injecting TgM83 +/− mice with mouse-passaged MSA into the sc.n. followed by a second injection with PFFs at 30, 45, and 60% of the MSA incubation period. We found that the two α-synuclein strains exhibited a synergistic effect during neuroinvasion, which was characterized by a decrease in incubation period along with evidence of the mouse-passaged MSA strain in the brain of terminal animals. These findings indicate that two α-synuclein strains can synergize with one another to accelerate the progression of clinical disease, representing a novel outcome in mixed infection studies.

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 (PrP Sc ) 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 PrP Sc 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.

In synucleinopathies, the protein α-synuclein misfolds into Lewy bodies (LBs) in patients with Lewy body disease (LBD) or into glial cytoplasmic inclusions (GCIs) in patients with multiple system atrophy (MSA). The ability of a single misfolded protein to cause disparate diseases is explained by the prion strain hypothesis, which argues that protein conformation is a major determinant of disease. While structural, biochemical, and biological studies show that LBD and MSA patient samples contain distinct α-synuclein strains, we recently reported the unexpected finding of a novel α-synuclein strain in a Parkinson’s disease with dementia patient sample containing GCI-like co-pathology along with widespread LB pathology. This finding led us to question if two α-synuclein strains can interact with one another in a patient and, if so, can strain competition occur. Notably, this would not only impact the clinical presentation of disease but would also have profound impacts on successful therapeutic development. To test this possibility, we used the strain interference superinfection model developed in the prion field, in which a slower replicating strain—in this study, mouse-passaged MSA—is used to compete with a faster replicating strain—here, recombinant preformed fibrils (PFFs)— following sciatic nerve (sc.n.) inoculation. Unexpectedly, we found that PFFs generated using the same method differed in their ability to neuroinvade following sc.n. inoculation based on α-synuclein monomer source. Using a PFF preparation that does spread from the periphery, we conducted strain competition studies by first injecting TgM83 +/− mice with mouse-passaged MSA into the sc.n. followed by a second injection with PFFs at 30, 45, and 60% of the MSA incubation period. Unlike in the prion field, where the faster replicating strain inhibits the slower strain at the 30 and 45% time points, we found that the two α-synuclein strains exhibited a synergistic effect during neuroinvasion. Notably, disease onset across the three cohorts was shortened compared to MSA inoculation alone, and brains from terminal animals showed evidence of both the PFF and mouse-passaged MSA strains, suggesting the two strains worked together to accelerate neuroinvasion in the mice. These findings have important implications for disease progression in patients with α-synuclein co-pathologies. The finding that two strains can synergize with one another to accelerate the progression of clinical disease represents a novel outcome in mixed infection studies and more broadly expands our understanding of the effect of prion strain biology on disease pathogenesis.

Chronic Wasting Disease (CWD) is a prion disease that affects Cervidae species, and is the only known prion disease transmitted among wildlife species. The key pathological feature is the conversion of the normal prion protein (PrPC) misfolding into abnormal forms (PrPSc), triggering the onset of CWD infections. The misfolding can generate distinct PrPSc conformations (strains) giving rise to diverse disease phenotypes encompassing pathology, incubation period, and clinical signs. These phenotypes operationally define distinct prion strains, a pivotal element in monitoring CWD spread and zoonotic potential—a complex endeavor compounded by defining and tracking CWD strains. This review pursues a tripartite objective: 1. to address the intricate challenges inherent in ongoing CWD strain classification; 2. to provide an overview of the known CWD-infected isolates, the strains they represent and their passage history; and 3. to describe the spatial diversity of CWD strains in North America, enriching our understanding of CWD strain dynamics. By delving into these dimensions, this review sheds light on the intricate interplay among polymorphisms, biochemical properties, and clinical expressions of CWD. This endeavor aims to elevate the trajectory of CWD research, advancing our insight into prion disease.

Soil_Cntrl_Expmts_Data.csv This data includes all control experiments conducted prior to testing study site test samples. I.e. negative soil experiments and inoculation/spiking soil experiments. We described this dataset and outline the full sample/data collection and processing protocols in a.Grunklee et al., In review. We collected this data to inform the sample processing protocol which we then used on the study site soil samples (b.Grunklee et al., In review). Soil_Test_Samples_Data.csv This data includes all experiments involved in the testing of the Beltrami County study site soil samples (i.e. those within the dump site, around the CWD+ farm, and immediately around the dump site). We described this dataset and outline the full sample/data collection and processing protocols in b.Grunklee et al. In review. Each plate had at least 1 representative negative control Alfisol or Histosol soil types followed by the study site test soil samples in question. Note: all of these soil samples were initially dried and run in a soil dilution of 10^-1 prior to RT-QuIC analysis per negative soil experimental results (a.Grunklee et al., In review). The Soil_Cntrl_Expmts_Data.csv dataset informed our sample processing and analysis protocols for the study site samples contained in the Soil_Test_Samples_Data.csv dataset. Per the results of the Soil_Cntrl_Expmts_Data.csv dataset, we dried and ran study site soil samples in a soil dilution of 10^-1 prior to RT-QuIC analysis (a.Grunklee et al., In review). These data describe prion detections in soil using real-time quaking-induced conversion (RT-QuIC) assay with various metric calculations common to RT-QuIC. The Soil_Cntrl_Expmts_Data.xlsx file contains data from a series of control experiments aimed at optimizing and applying RT-QuIC for the detection of chronic wasting disease prions in environmental soil samples. We focused negative control experiments on refining RT-QuIC and sample processing to use on Minnesota native soils, which included limiting background noise from the samples. Starting on 2023-05-08, we used spiked soil control experiments to distinguish true prion signal from background noise and validate detection reliability. Following soil control experiments, the Soil_Test_Samples_Data.xlsx file describes our sample testing in RT-QuIC collected from our study site, an illegal white-tailed deer (Odocoileus virginianus, WTD) carcass disposal site and a nearby captive WTD farm in Beltrami County, Minnesota. We analyzed study site soil samples for prion presence to assess potential environmental contamination associated with improper carcass disposal practices. This study was funded by the Minnesota Environment and Natural Resource Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources [2020-087 and 2022-217] and the Conservation Science Graduate Program at the University of Minnesota Twin Cities. Grunklee, Madeline K; Bartz, Jason C; Karwan, Diana L; Lichtenberg, Stuart S; Lurndahl, Nicole A; Larsen, Peter A; Schwabenlander, Marc D; Rowden, Gage R; Li, E Anu; Yuan, Qi; Wolf, Tiffany M. (2025). Supporting Dataset for "RT-QuIC Optimization for Prion Detection in Two Minnesota Soil Types" and "Detection of Chronic Wasting Disease Prions in Soil at an Illegal White-tailed Deer Carcass Disposal Site". Retrieved from the Data Repository for the University of Minnesota (DRUM), https://hdl.handle.net/11299/270027.