Clay Components in Soil Dictate Environmental Stability and Bioavailability of Cervid Prions in Mice
Original Research ARTICLE
Clay Components in Soil Dictate Environmental Stability and Bioavailability of Cervid Prions in Mice
A. Christy Wyckoff1, 
Sarah Kane1, Krista Lockwood1, Jeff Seligman1, Brady Michel1, Dana Hill1, Aimee Ortega1, Mihnea R. Mangalea1, Glenn C. Telling1, Michael W. Miller2, Kurt Vercauteren3 and 
Mark D. Zabel1*- 1Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Prion Research Center at Colorado State University, Fort Collins, CO, USA
- 2Colorado Parks and Wildlife, Fort Collins, CO, USA
- 3National Wildlife Research Center, Wildlife Services, United States Department of Agriculture, Fort Collins, CO, USA
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Discussion
Here we report that chronic exposure to naturally contaminated soil is sufficient for CWD transmission in prion susceptible mice. This was previously shown in captive mule deer, a natural host species. However, direct transmission from nonclinical animals in endemic areas could not be definitively excluded and indirect transmission from environmental sources remained a poorly quantified component of CWD transmission. We have demonstrated, for the first time, that soil from pens that previously housed prion infected animals transmitted CWD prions to susceptible transgenic mice bred in prion-free conditions. We observed terminal clinical signs and classic CWD neuropathology in 3/40 mice continuously housed for 1 year on prion-contaminated MD or elk pen soil. We also detected subclinical prion infection in an additional five mice, resulting in transmission rates comparable to prevalence estimates for natural cervid hosts in CWD endemic areas. These data confirm that these pen soils contain infectious prions that can be indirectly transmitted, and that Tg(cerPrP)5037 mice can accurately model indirect CWD transmission.
This study also supports the debated hypothesis that CWD prions bound to soil are more infectious (Johnson et al., 2007) than prions without soil. None of the 39 mice orally inoculated with three unique CWD isolates demonstrated clinical illness. However, 3/105 mice inoculated with the equal or lower doses of CWD prions plus soil progressed to terminal clinical disease. PMCA revealed significantly more mice with subclinical levels of CWD prions when fed prions with soil than with prions alone. We also observed a higher percentage of subclinical mice after feeding them a single dose of MD pen and elk pen soil (11.1%, n = 90) than mice fed high doses of unbound CWD prion isolates (7.7%, n = 39) and comparable to percentages of subclinical mice fed 108 and 5 × 107 LD50 units of E2 with soil (12.2%, n = 90). These observations also provide an estimate of the prion titers contained in those pen soils.
Moreover, we detected significantly higher prion titers in brains of subclinical mice acutely and chronically exposed to prions with soil than mice fed unbound CWD prions. Overall, the proportion of mice testing positive for CWD by PMCA after a single oral dose of prions with soil (4.4–21.7%) were comparable to infection rates of mice continuously housed on the pen soils (15–20%). These proportions are far lower than has been reported for natural hosts housed in the pens from which we sourced the soil (Miller and Williams, 2003). However, cervids in those pens inhabited those pens their entire lives, in contrast to mice housed on soil for just 1 year. No data exists for the prevalence of infected cervids after the first year in those pens. Different digestive physiology in mice, which have simple stomachs, vs. the four-chambered stomachs of cervids and sheep, could also contribute to differences in incidence.
Typical experimental challenge studies use a single dose of infectious material, but we agree with Williams et al. (Miller and Williams, 2004; Williams, 2005) that this is not representative of a natural course of infection and likely underestimates the timeframe of a typical natural infection. Instead the total lifetime exposure dose directly influences the disease time course and possibly intensity. Thus, mice housed on contaminated soil were more likely to become infected, and to contract clinical disease, than mice treated with the same soil in a single p.o. dose.
The difference observed between the chronic exposure treatments of MD pen soil and the elk soil could be due to titer differences. The Wyoming elk pens routinely have new cases of CWD in captive elk, while the Colorado mule deer pens have been housing fewer deer and noticed a decline in new cases within the captive deer. Alternatively, prevalence differences could be due to CWD prion strain differences or host PrP sequence. The mice used in this study were transgenic for the elk Prnp gene, and incidence was highest in mice housed on the elk pen soil as compared to the MD pen soil. The difference between incidences at facilities could be dependent on soil differences.
All soils tested here exhibited increasing prion binding capacity with increasing clay content that we hypothesize dictates environmental stability. Our experiments showing Mte potentiated soil binding to prions, as well as evidence demonstrating increased infectivity of soil bound prions (Johnson et al., 2007) and correlations of soil clay content with disease prevalence (Walter et al., 2011) supports this hypothesis. We have successfully used our transgenic mouse chronic exposure model and BASICS to measure environmental contamination, degradation rates, and rates of transmission over time. We can further apply these tools to forecast and/or estimate the ecology of the disease at the population and landscape level.
Even less is known about how soil influences prion uptake, retention, replication and infection in affected animals. Here we report that mice absorbed prions bound to soil significantly faster from the stomach and retained soil-bound prions significantly longer in the cecum, lymph nodes and spleen than unbound prions. Soil likely facilitated prion transport from the stomach to the small intestine, where we showed CD24 positive epithelial cells, including enterocytes and M cells previously shown to take up prions (Foster and Macpherson, 2010; Da Costa Dias et al., 2011; Donaldson et al., 2012; Kincaid et al., 2012), retain prions longer than unbound prions. Later, soil-bound prions were captured mainly by CD11b+/F4/80+ macrophages in Peyer's patches and spleen. Macrophages likely transfer soil-bound prions to CD21/35+ B cells, which can transport them to germinal centers for robust replication by follicular dendritic cells, as we have shown previously (Michel et al., 2012b). Increased detection of unbound prions excreted into feces compared to soil bound prions confirmed retention in the gut, lymph nodes and spleen. Increased retention likely potentiates early replication, later dissemination and ultimately neuroinvasion, which leads to increased neuronal replication and progression to terminal CWD. Thus, soil can increase both environmental stability and bioavailability of prions that it binds.
These findings have implications for human exposure to, and facilitated uptake of CWD prions on the landscape. Soil likely facilitates inhalation and even ingestion of prions by hunters, hikers and wildlife professionals in the environment. A significant species barrier exists that limits prion disease transmission from cervids to humans (Miller and Williams, 2004; Williams, 2005). But soil may alter this barrier and facilitate rapid and efficient absorption of prions into mucosal tissues that drain into lymphoid tissue where zoonotic prion replication could occur. We are currently exploring this possibility.
Long-term environmental reservoirs of pathogens contribute to the epidemiology of many diseases including avian influenza, anthrax, hanta virus and botulism (Kallio et al., 2006; Rohani et al., 2009). Quantifying titers and persistence of PrPCWD in the environment has been particularly challenging due to limited sensitivity of existing laboratory assays. Our findings significantly advance our understanding of the influence of soil on environmental prion exposure and transmission, and the pathobiology of prions ingested by animals in this context.
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Friday, February 25, 2011
Soil clay content underlies prion infection odds
Tuesday, June 07, 2016
How Did CWD Get Way Down In Medina County, Texas?
*** Infectious agent of sheep scrapie may persist in the environment for at least 16 years ***
Gudmundur Georgsson1, Sigurdur Sigurdarson2 and Paul Brown3
Using in vitro prion replication for high sensitive detection of prions and prionlike proteins and for understanding mechanisms of transmission.
Claudio Soto
Mitchell Center for Alzheimer's diseases and related Brain disorders, Department of Neurology, University of Texas Medical School at Houston.
Prion and prion-like proteins are misfolded protein aggregates with the ability to selfpropagate to spread disease between cells, organs and in some cases across individuals. I n T r a n s m i s s i b l e s p o n g i f o r m encephalopathies (TSEs), prions are mostly composed by a misfolded form of the prion protein (PrPSc), which propagates by transmitting its misfolding to the normal prion protein (PrPC). The availability of a procedure to replicate prions in the laboratory may be important to study the mechanism of prion and prion-like spreading and to develop high sensitive detection of small quantities of misfolded proteins in biological fluids, tissues and environmental samples. Protein Misfolding Cyclic Amplification (PMCA) is a simple, fast and efficient methodology to mimic prion replication in the test tube. PMCA is a platform technology that may enable amplification of any prion-like misfolded protein aggregating through a seeding/nucleation process. In TSEs, PMCA is able to detect the equivalent of one single molecule of infectious PrPSc and propagate prions that maintain high infectivity, strain properties and species specificity. Using PMCA we have been able to detect PrPSc in blood and urine of experimentally infected animals and humans affected by vCJD with high sensitivity and specificity. Recently, we have expanded the principles of PMCA to amplify amyloid-beta (Aβ) and alphasynuclein (α-syn) aggregates implicated in Alzheimer's and Parkinson's diseases, respectively. Experiments are ongoing to study the utility of this technology to detect Aβ and α-syn aggregates in samples of CSF and blood from patients affected by these diseases.
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***Recently, we have been using PMCA to study the role of environmental prion contamination on the horizontal spreading of TSEs. These experiments have focused on the study of the interaction of prions with plants and environmentally relevant surfaces. Our results show that plants (both leaves and roots) bind tightly to prions present in brain extracts and excreta (urine and feces) and retain even small quantities of PrPSc for long periods of time. Strikingly, ingestion of prioncontaminated leaves and roots produced disease with a 100% attack rate and an incubation period not substantially longer than feeding animals directly with scrapie brain homogenate. Furthermore, plants can uptake prions from contaminated soil and transport them to different parts of the plant tissue (stem and leaves). Similarly, prions bind tightly to a variety of environmentally relevant surfaces, including stones, wood, metals, plastic, glass, cement, etc. Prion contaminated surfaces efficiently transmit prion disease when these materials were directly injected into the brain of animals and strikingly when the contaminated surfaces were just placed in the animal cage. These findings demonstrate that environmental materials can efficiently bind infectious prions and act as carriers of infectivity, suggesting that they may play an important role in the horizontal transmission of the disease.
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Since its invention 13 years ago, PMCA has helped to answer fundamental questions of prion propagation and has broad applications in research areas including the food industry, blood bank safety and human and veterinary disease diagnosis.
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with CWD TSE Prions, I am not sure there is any absolute yet, other than what we know with transmission studies, and we know tse prion kill, and tse prion are bad. science shows to date, that indeed soil, dirt, some better than others, can act as a carrier. same with objects, farm furniture. take it with how ever many grains of salt you wish, or not. if load factor plays a role in the end formula, then everything should be on the table, in my opinion...tss
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***Recently, we have been using PMCA to study the role of environmental prion contamination on the horizontal spreading of TSEs. These experiments have focused on the study of the interaction of prions with plants and environmentally relevant surfaces. Our results show that plants (both leaves and roots) bind tightly to prions present in brain extracts and excreta (urine and feces) and retain even small quantities of PrPSc for long periods of time. Strikingly, ingestion of prioncontaminated leaves and roots produced disease with a 100% attack rate and an incubation period not substantially longer than feeding animals directly with scrapie brain homogenate. Furthermore, plants can uptake prions from contaminated soil and transport them to different parts of the plant tissue (stem and leaves). Similarly, prions bind tightly to a variety of environmentally relevant surfaces, including stones, wood, metals, plastic, glass, cement, etc. Prion contaminated surfaces efficiently transmit prion disease when these materials were directly injected into the brain of animals and strikingly when the contaminated surfaces were just placed in the animal cage. These findings demonstrate that environmental materials can efficiently bind infectious prions and act as carriers of infectivity, suggesting that they may play an important role in the horizontal transmission of the disease.
Since its invention 13 years ago, PMCA has helped to answer fundamental questions of prion propagation and has broad applications in research areas including the food industry, blood bank safety and human and veterinary disease diagnosis.
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Oral Transmissibility of Prion Disease Is Enhanced by Binding to Soil Particles
Author Summary
Transmissible spongiform encephalopathies (TSEs) are a group of incurable neurological diseases likely caused by a misfolded form of the prion protein. TSEs include scrapie in sheep, bovine spongiform encephalopathy (‘‘mad cow’’ disease) in cattle, chronic wasting disease in deer and elk, and Creutzfeldt-Jakob disease in humans. Scrapie and chronic wasting disease are unique among TSEs because they can be transmitted between animals, and the disease agents appear to persist in environments previously inhabited by infected animals. Soil has been hypothesized to act as a reservoir of infectivity and to bind the infectious agent. In the current study, we orally dosed experimental animals with a common clay mineral, montmorillonite, or whole soils laden with infectious prions, and compared the transmissibility to unbound agent. We found that prions bound to montmorillonite and whole soils remained orally infectious, and, in most cases, increased the oral transmission of disease compared to the unbound agent. The results presented in this study suggest that soil may contribute to environmental spread of TSEs by increasing the transmissibility of small amounts of infectious agent in the environment.
tse prion soil
Wednesday, December 16, 2015
Objects in contact with classical scrapie sheep act as a reservoir for scrapie transmission
The sources of dust borne prions are unknown but it seems reasonable to assume that faecal, urine, skin, parturient material and saliva-derived prions may contribute to this mobile environmental reservoir of infectivity. This work highlights a possible transmission route for scrapie within the farm environment, and this is likely to be paralleled in CWD which shows strong similarities with scrapie in terms of prion dissemination and disease transmission. The data indicate that the presence of scrapie prions in dust is likely to make the control of these diseases a considerable challenge.
>>>Particle-associated PrPTSE molecules may migrate from locations of deposition via transport processes affecting soil particles, including entrainment in and movement with air and overland flow. <<<
Fate of Prions in Soil: A Review
Christen B. Smith, Clarissa J. Booth, and Joel A. Pedersen*
Several reports have shown that prions can persist in soil for several years. Significant interest remains in developing methods that could be applied to degrade PrPTSE in naturally contaminated soils. Preliminary research suggests that serine proteases and the microbial consortia in stimulated soils and compost may partially degrade PrPTSE. Transition metal oxides in soil (viz. manganese oxide) may also mediate prion inactivation. Overall, the effect of prion attachment to soil particles on its persistence in the environment is not well understood, and additional study is needed to determine its implications on the environmental transmission of scrapie and CWD.
P.161: Prion soil binding may explain efficient horizontal CWD transmission
Conclusion. Silty clay loam exhibits highly efficient prion binding, inferring a durable environmental reservoir, and an efficient mechanism for indirect horizontal CWD transmission.
>>>Another alternative would be an absolute prohibition on the movement of deer within the state for any purpose. While this alternative would significantly reduce the potential spread of CWD, it would also have the simultaneous effect of preventing landowners and land managers from implementing popular management strategies involving the movement of deer, and would deprive deer breeders of the ability to engage in the business of buying and selling breeder deer. Therefore, this alternative was rejected because the department determined that it placed an avoidable burden on the regulated community.<<<
Wednesday, December 16, 2015
Objects in contact with classical scrapie sheep act as a reservoir for scrapie transmission
Timm Konold1*, Stephen A. C. Hawkins2, Lisa C. Thurston3, Ben C. Maddison4, Kevin C. Gough5, Anthony Duarte1 and Hugh A. Simmons1
1 Animal Sciences Unit, Animal and Plant Health Agency Weybridge, Addlestone, UK, 2 Pathology Department, Animal and Plant Health Agency Weybridge, Addlestone, UK, 3 Surveillance and Laboratory Services, Animal and Plant Health Agency Penrith, Penrith, UK, 4 ADAS UK, School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, UK, 5 School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, UK
Classical scrapie is an environmentally transmissible prion disease of sheep and goats. Prions can persist and remain potentially infectious in the environment for many years and thus pose a risk of infecting animals after re-stocking. In vitro studies using serial protein misfolding cyclic amplification (sPMCA) have suggested that objects on a scrapie affected sheep farm could contribute to disease transmission. This in vivo study aimed to determine the role of field furniture (water troughs, feeding troughs, fencing, and other objects that sheep may rub against) used by a scrapie-infected sheep flock as a vector for disease transmission to scrapie-free lambs with the prion protein genotype VRQ/VRQ, which is associated with high susceptibility to classical scrapie. When the field furniture was placed in clean accommodation, sheep became infected when exposed to either a water trough (four out of five) or to objects used for rubbing (four out of seven). This field furniture had been used by the scrapie-infected flock 8 weeks earlier and had previously been shown to harbor scrapie prions by sPMCA. Sheep also became infected (20 out of 23) through exposure to contaminated field furniture placed within pasture not used by scrapie-infected sheep for 40 months, even though swabs from this furniture tested negative by PMCA. This infection rate decreased (1 out of 12) on the same paddock after replacement with clean field furniture. Twelve grazing sheep exposed to field furniture not in contact with scrapie-infected sheep for 18 months remained scrapie free. The findings of this study highlight the role of field furniture used by scrapie-infected sheep to act as a reservoir for disease re-introduction although infectivity declines considerably if the field furniture has not been in contact with scrapie-infected sheep for several months. PMCA may not be as sensitive as VRQ/VRQ sheep to test for environmental contamination.
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Discussion
Classical scrapie is an environmentally transmissible disease because it has been reported in naïve, supposedly previously unexposed sheep placed in pastures formerly occupied by scrapie-infected sheep (4, 19, 20). Although the vector for disease transmission is not known, soil is likely to be an important reservoir for prions (2) where – based on studies in rodents – prions can adhere to minerals as a biologically active form (21) and remain infectious for more than 2 years (22). Similarly, chronic wasting disease (CWD) has re-occurred in mule deer housed in paddocks used by infected deer 2 years earlier, which was assumed to be through foraging and soil consumption (23).
Our study suggested that the risk of acquiring scrapie infection was greater through exposure to contaminated wooden, plastic, and metal surfaces via water or food troughs, fencing, and hurdles than through grazing. Drinking from a water trough used by the scrapie flock was sufficient to cause infection in sheep in a clean building. Exposure to fences and other objects used for rubbing also led to infection, which supported the hypothesis that skin may be a vector for disease transmission (9). The risk of these objects to cause infection was further demonstrated when 87% of 23 sheep presented with PrPSc in lymphoid tissue after grazing on one of the paddocks, which contained metal hurdles, a metal lamb creep and a water trough in contact with the scrapie flock up to 8 weeks earlier, whereas no infection had been demonstrated previously in sheep grazing on this paddock, when equipped with new fencing and field furniture. When the contaminated furniture and fencing were removed, the infection rate dropped significantly to 8% of 12 sheep, with soil of the paddock as the most likely source of infection caused by shedding of prions from the scrapie-infected sheep in this paddock up to a week earlier.
This study also indicated that the level of contamination of field furniture sufficient to cause infection was dependent on two factors: stage of incubation period and time of last use by scrapie-infected sheep. Drinking from a water trough that had been used by scrapie sheep in the predominantly pre-clinical phase did not appear to cause infection, whereas infection was shown in sheep drinking from the water trough used by scrapie sheep in the later stage of the disease. It is possible that contamination occurred through shedding of prions in saliva, which may have contaminated the surface of the water trough and subsequently the water when it was refilled. Contamination appeared to be sufficient to cause infection only if the trough was in contact with sheep that included clinical cases. Indeed, there is an increased risk of bodily fluid infectivity with disease progression in scrapie (24) and CWD (25) based on PrPSc detection by sPMCA. Although ultraviolet light and heat under natural conditions do not inactivate prions (26), furniture in contact with the scrapie flock, which was assumed to be sufficiently contaminated to cause infection, did not act as vector for disease if not used for 18 months, which suggest that the weathering process alone was sufficient to inactivate prions.
PrPSc detection by sPMCA is increasingly used as a surrogate for infectivity measurements by bioassay in sheep or mice. In this reported study, however, the levels of PrPSc present in the environment were below the limit of detection of the sPMCA method, yet were still sufficient to cause infection of in-contact animals. In the present study, the outdoor objects were removed from the infected flock 8 weeks prior to sampling and were positive by sPMCA at very low levels (2 out of 37 reactions). As this sPMCA assay also yielded 2 positive reactions out of 139 in samples from the scrapie-free farm, the sPMCA assay could not detect PrPSc on any of the objects above the background of the assay. False positive reactions with sPMCA at a low frequency associated with de novo formation of infectious prions have been reported (27, 28). This is in contrast to our previous study where we demonstrated that outdoor objects that had been in contact with the scrapie-infected flock up to 20 days prior to sampling harbored PrPSc that was detectable by sPMCA analysis [4 out of 15 reactions (12)] and was significantly more positive by the assay compared to analogous samples from the scrapie-free farm. This discrepancy could be due to the use of a different sPMCA substrate between the studies that may alter the efficiency of amplification of the environmental PrPSc. In addition, the present study had a longer timeframe between the objects being in contact with the infected flock and sampling, which may affect the levels of extractable PrPSc. Alternatively, there may be potentially patchy contamination of this furniture with PrPSc, which may have been missed by swabbing. The failure of sPMCA to detect CWD-associated PrP in saliva from clinically affected deer despite confirmation of infectivity in saliva-inoculated transgenic mice was associated with as yet unidentified inhibitors in saliva (29), and it is possible that the sensitivity of sPMCA is affected by other substances in the tested material. In addition, sampling of amplifiable PrPSc and subsequent detection by sPMCA may be more difficult from furniture exposed to weather, which is supported by the observation that PrPSc was detected by sPMCA more frequently in indoor than outdoor furniture (12). A recent experimental study has demonstrated that repeated cycles of drying and wetting of prion-contaminated soil, equivalent to what is expected under natural weathering conditions, could reduce PMCA amplification efficiency and extend the incubation period in hamsters inoculated with soil samples (30). This seems to apply also to this study even though the reduction in infectivity was more dramatic in the sPMCA assays than in the sheep model. Sheep were not kept until clinical end-point, which would have enabled us to compare incubation periods, but the lack of infection in sheep exposed to furniture that had not been in contact with scrapie sheep for a longer time period supports the hypothesis that prion degradation and subsequent loss of infectivity occurs even under natural conditions.
In conclusion, the results in the current study indicate that removal of furniture that had been in contact with scrapie-infected animals should be recommended, particularly since cleaning and decontamination may not effectively remove scrapie infectivity (31), even though infectivity declines considerably if the pasture and the field furniture have not been in contact with scrapie-infected sheep for several months. As sPMCA failed to detect PrPSc in furniture that was subjected to weathering, even though exposure led to infection in sheep, this method may not always be reliable in predicting the risk of scrapie infection through environmental contamination. These results suggest that the VRQ/VRQ sheep model may be more sensitive than sPMCA for the detection of environmentally associated scrapie, and suggest that extremely low levels of scrapie contamination are able to cause infection in susceptible sheep genotypes.
Keywords: classical scrapie, prion, transmissible spongiform encephalopathy, sheep, field furniture, reservoir, serial protein misfolding cyclic amplification
Wednesday, December 16, 2015
*** Objects in contact with classical scrapie sheep act as a reservoir for scrapie transmission ***
*** Infectious agent of sheep scrapie may persist in the environment for at least 16 years ***
Gudmundur Georgsson1, Sigurdur Sigurdarson2 and Paul Brown3
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Thursday, June 09, 2016
Scrapie Field Trial Experiments Mission, Texas, The Moore Air Force Base Scrapie TSE Prion Experiment 1964
Scrapie Field Trial Experiments Mission, Texas, The Moore Air Force Base Scrapie Experiment 1964
How Did CWD Get Way Down In Medina County, Texas?
Confucius ponders...
Could the Scrapie experiments back around 1964 at Moore Air Force near Mission, Texas, could this area have been ground zero for CWD TSE Prion (besides the CWD cases that have waltzed across the Texas, New Mexico border near WSMR Trans Pecos region since around 2001)?
Epidemiology of Scrapie in the United States 1977
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Scrapie Field Trial Experiments Mission, Texas
A Scrapie Field Trial was developed at Mission, Texas, to provide additional information for the eradication program on the epidemiology of natural scrapie. The Mission Field Trial Station is located on 450 acres of pastureland, part of the former Moore Air Force Base, near Mission, Texas. It was designed to bring previously exposed, and later also unexposed, sheep or goats to the Station and maintain and breed them under close observation for extended periods to determine which animals would develop scrapie and define more closely the natural spread and other epidemiological aspects of the disease.
The 547 previously exposed sheep brought to the Mission Station beginning in 1964 were of the Cheviot, Hampshire, Montadale, or Suffolk breeds. They were purchased as field outbreaks occurred, and represented 21 bloodlines in which scrapie had been diagnosed. Upon arrival at the Station, the sheep were maintained on pasture, with supplemental feeding as necessary. The station was divided into 2 areas: (1) a series of pastures and-pens occupied by male animals only, and (2) a series of pastures and pens occupied by females and young progeny of both sexes. ...
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Mission, Texas Scrapie transmission to cattle study
Wilbur Clarke (reference the Mission, Texas scrapie transmission transmission to cattle study) is now the State Veterinarian for Montana based at Helena.
I was given confidential access to sections from the Clarke scrapie-cattle transmission experiment. Details of the experimental design were as supplied previously by Dr. Wrathall (copy of relevant information appended). Only 3 animals (2 inoculated with 2nd pass Suffolk scrapie and 1 inoculated with Angora goat passaged scrapie) showed clinical signs. Clinical signs were characterised by weakness, ''a stilted hindlimb gait'', disorientation, ataxia and, terminally, lateral recumbency. The two cattle from which I examined material were inocluated at 8 months of age and developed signs 36 months pi (goat scrapie inoculum) and 49 months pi (one of the Suffolk scrapie inoculated) respectively. This latter animal was killed at 58 months of age and so the clinical duration was only 1 month. The neuropathology was somewhat different from BSE or the Stetsonville TME in cattle. Vacuolar changes were minimal, to the extent that detection REQUIRED CAREFUL SEARCHING. Conversely astrocyte hypertrophy was a widespread and prominent feature. The material requires DETAILED NEUROPATHOLOGICAL ASSESSMENT BUT WHETHER OR NOT THIS WILL BE DONE REMAINS A QUESTION.
Transmission Studies
Thursday, December 08, 2016
USDA APHIS National Scrapie Eradication Program October 2016 Monthly Report Fiscal Year 2017 atypical NOR-98 Scrapie
Title: Pathological features of chronic wasting disease in reindeer and demonstration of horizontal transmission
Monday, September 05, 2016
Pathological features of chronic wasting disease in reindeer and demonstration of horizontal transmission Major Findings for Norway
Thursday, September 22, 2016
NORWAY DETECTS 5TH CASE OF CHRONIC WASTING DISEASE CWD TSE PRION Skrantesjuke
SUNDAY, OCTOBER 02, 2016
*** What is the risk of a cervid TSE being introduced from Norway into Great Britain? Qualitative Risk Assessment September 2016
Wednesday, September 7, 2016
*** An assessment of the long-term persistence of prion infectivity in aquatic environments
http://transmissiblespongiformencephalopathy.blogspot.com/2016/09/an-assessment-of-long-term-persistence.html
Friday, September 02, 2016
*** Chronic Wasting Disease Drives Population Decline of White-Tailed Deer
Wednesday, December 07, 2016
*** WDA 2016 NEW YORK ***
We found that CWD adapts to a new host more readily than BSE and that human PrP was unexpectedly prone to misfolding by CWD prions. In addition, we investigated the role of specific regions of the bovine, deer and human PrP protein in resistance to conversion by prions from another species. We have concluded that the human protein has a region that confers unusual susceptibility to conversion by CWD prions.
Student Presentations Session 2
The species barriers and public health threat of CWD and BSE prions
Ms. Kristen Davenport1, Dr. Davin Henderson1, Dr. Candace Mathiason1, Dr. Edward Hoover1 1Colorado State University
Chronic wasting disease (CWD) is spreading rapidly through cervid populations in the USA. Bovine spongiform encephalopathy (BSE, mad cow disease) arose in the 1980s because cattle were fed recycled animal protein. These and other prion diseases are caused by abnormal folding of the normal prion protein (PrP) into a disease causing form (PrPd), which is pathogenic to nervous system cells and can cause subsequent PrP to misfold. CWD spreads among cervids very efficiently, but it has not yet infected humans. On the other hand, BSE was spread only when cattle consumed infected bovine or ovine tissue, but did infect humans and other species. The objective of this research is to understand the role of PrP structure in cross-species infection by CWD and BSE. To study the propensity of each species’ PrP to be induced to misfold by the presence of PrPd from verious species, we have used an in vitro system that permits detection of PrPd in real-time. We measured the conversion efficiency of various combinations of PrPd seeds and PrP substrate combinations. We observed the cross-species behavior of CWD and BSE, in addition to feline-adapted CWD and BSE. We found that CWD adapts to a new host more readily than BSE and that human PrP was unexpectedly prone to misfolding by CWD prions. In addition, we investigated the role of specific regions of the bovine, deer and human PrP protein in resistance to conversion by prions from another species. We have concluded that the human protein has a region that confers unusual susceptibility to conversion by CWD prions. CWD is unique among prion diseases in its rapid spread in natural populations. BSE prions are essentially unaltered upon passage to a new species, while CWD adapts to the new species. This adaptation has consequences for surveillance of humans exposed to CWD.
Wildlife Disease Risk Communication Research Contributes to Wildlife Trust Administration Exploring perceptions about chronic wasting disease risks among wildlife and agriculture professionals and stakeholders
http://www.wda2016.org/uploads/5/8/6/1/58613359/wda_2016_conference_proceedings_low_res.pdf
PRION 2016 TOKYO
Zoonotic Potential of CWD Prions: An Update
Ignazio Cali1, Liuting Qing1, Jue Yuan1, Shenghai Huang2, Diane Kofskey1,3, Nicholas Maurer1, Debbie McKenzie4, Jiri Safar1,3,5, Wenquan Zou1,3,5,6, Pierluigi Gambetti1, Qingzhong Kong1,5,6 1Department of Pathology, 3National Prion Disease Pathology Surveillance Center, 5Department of Neurology, 6National Center for Regenerative Medicine, Case Western Reserve University, Cleveland, OH 44106, USA. 4Department of Biological Sciences and Center for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Alberta, Canada, 2Encore Health Resources, 1331 Lamar St, Houston, TX 77010
Chronic wasting disease (CWD) is a widespread and highly transmissible prion disease in free-ranging and captive cervid species in North America. The zoonotic potential of CWD prions is a serious public health concern, but the susceptibility of human CNS and peripheral organs to CWD prions remains largely unresolved. We reported earlier that peripheral and CNS infections were detected in transgenic mice expressing human PrP129M or PrP129V. Here we will present an update on this project, including evidence for strain dependence and influence of cervid PrP polymorphisms on CWD zoonosis as well as the characteristics of experimental human CWD prions.
PRION 2016 TOKYO In Conjunction with Asia Pacific Prion Symposium 2016 PRION 2016 Tokyo Prion 2016
http://prion2016.org/dl/newsletter_03.pdf
Cervid to human prion transmission
Kong, Qingzhong
Case Western Reserve University, Cleveland, OH, United States
Abstract
Prion disease is transmissible and invariably fatal. Chronic wasting disease (CWD) is the prion disease affecting deer, elk and moose, and it is a widespread and expanding epidemic affecting 22 US States and 2 Canadian provinces so far. CWD poses the most serious zoonotic prion transmission risks in North America because of huge venison consumption (>6 million deer/elk hunted and consumed annually in the USA alone), significant prion infectivity in muscles and other tissues/fluids from CWD-affected cervids, and usually high levels of individual exposure to CWD resulting from consumption of the affected animal among often just family and friends. However, we still do not know whether CWD prions can infect humans in the brain or peripheral tissues or whether clinical/asymptomatic CWD zoonosis has already occurred, and we have no essays to reliably detect CWD infection in humans. We hypothesize that:
(1) The classic CWD prion strain can infect humans at low levels in the brain and peripheral lymphoid tissues;
(2) The cervid-to-human transmission barrier is dependent on the cervid prion strain and influenced by the host (human) prion protein (PrP) primary sequence;
(3) Reliable essays can be established to detect CWD infection in humans;and
(4) CWD transmission to humans has already occurred. We will test these hypotheses in 4 Aims using transgenic (Tg) mouse models and complementary in vitro approaches.
Aim 1 will prove that the classical CWD strain may infect humans in brain or peripheral lymphoid tissues at low levels by conducting systemic bioassays in a set of "humanized" Tg mouse lines expressing common human PrP variants using a number of CWD isolates at varying doses and routes. Experimental "human CWD" samples will also be generated for Aim 3.
Aim 2 will test the hypothesis that the cervid-to-human prion transmission barrier is dependent on prion strain and influenced by the host (human) PrP sequence by examining and comparing the transmission efficiency and phenotypes of several atypical/unusual CWD isolates/strains as well as a few prion strains from other species that have adapted to cervid PrP sequence, utilizing the same panel of humanized Tg mouse lines as in Aim 1.
Aim 3 will establish reliable essays for detection and surveillance of CWD infection in humans by examining in details the clinical, pathological, biochemical and in vitro seeding properties of existing and future experimental "human CWD" samples generated from Aims 1-2 and compare them with those of common sporadic human Creutzfeldt-Jakob disease (sCJD) prions.
Aim 4 will attempt to detect clinical CWD-affected human cases by examining a significant number of brain samples from prion-affected human subjects in the USA and Canada who have consumed venison from CWD-endemic areas utilizing the criteria and essays established in Aim 3. The findings from this proposal will greatly advance our understandings on the potential and characteristics of cervid prion transmission in humans, establish reliable essays for CWD zoonosis and potentially discover the first case(s) of CWD infection in humans.
Public Health Relevance There are significant and increasing human exposure to cervid prions because chronic wasting disease (CWD, a widespread and highly infectious prion disease among deer and elk in North America) continues spreading and consumption of venison remains popular, but our understanding on cervid-to-human prion transmission is still very limited, raising public health concerns. This proposal aims to define the zoonotic risks of cervid prions and set up and apply essays to detect CWD zoonosis using mouse models and in vitro methods. The findings will greatly expand our knowledge on the potentials and characteristics of cervid prion transmission in humans, establish reliable essays for such infections and may discover the first case(s) of CWD infection in humans.
Funding Agency Agency National Institute of Health (NIH)
Institute National Institute of Neurological Disorders and Stroke (NINDS)
Type Research Project (R01)
Project # 1R01NS088604-01A1
Application # 9037884
Study Section Cellular and Molecular Biology of Neurodegeneration Study Section (CMND)
Program Officer Wong, May
Project Start 2015-09-30
Project End 2019-07-31
Budget Start 2015-09-30
Budget End 2016-07-31
Support Year 1
Fiscal Year 2015
Total Cost $337,507
Indirect Cost $118,756
Institution
Name Case Western Reserve University
Department Pathology
Type Schools of Medicine
DUNS # 077758407
City Cleveland
State OH
Country United States
Zip Code 44106
http://grantome.com/grant/NIH/R01-NS088604-01A1
Monday, May 02, 2016
*** Zoonotic Potential of CWD Prions: An Update Prion 2016 Tokyo ***
http://chronic-wasting-disease.blogspot.com/2016/05/zoonotic-potential-of-cwd-prions-update.html
http://www.tandfonline.com/doi/abs/10.1080/19336896.2016.1163048?journalCode=kprn20
why do we not want to do TSE transmission studies on chimpanzees $
5. A positive result from a chimpanzee challenged severly would likely create alarm in some circles even if the result could not be interpreted for man. I have a view that all these agents could be transmitted provided a large enough dose by appropriate routes was given and the animals kept long enough. Until the mechanisms of the species barrier are more clearly understood it might be best to retain that hypothesis.
snip...
R. BRADLEY
http://collections.europarchive.org/tna/20080102222950/http://www.bseinquiry.gov.uk/files/yb/1990/09/23001001.pdf
http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=313160
SCRAPIE WS-01: Prion diseases in animals and zoonotic potential 2016
Prion. 10:S15-S21. 2016 ISSN: 1933-6896 printl 1933-690X online
http://scrapie-usa.blogspot.com/2016/04/scrapie-ws-01-prion-diseases-in-animals.html
*** Zoonotic Potential of CWD Prions: An Update Prion 2016 Tokyo ***
http://chronic-wasting-disease.blogspot.com/2016/05/zoonotic-potential-of-cwd-prions-update.html
http://www.tandfonline.com/doi/abs/10.1080/19336896.2016.1163048?journalCode=kprn20
why do we not want to do TSE transmission studies on chimpanzees $
5. A positive result from a chimpanzee challenged severly would likely create alarm in some circles even if the result could not be interpreted for man. I have a view that all these agents could be transmitted provided a large enough dose by appropriate routes was given and the animals kept long enough. Until the mechanisms of the species barrier are more clearly understood it might be best to retain that hypothesis.
snip...
R. BRADLEY
http://collections.europarchive.org/tna/20080102222950/http://www.bseinquiry.gov.uk/files/yb/1990/09/23001001.pdf
http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=313160
SCRAPIE WS-01: Prion diseases in animals and zoonotic potential 2016
Prion. 10:S15-S21. 2016 ISSN: 1933-6896 printl 1933-690X online
http://scrapie-usa.blogspot.com/2016/04/scrapie-ws-01-prion-diseases-in-animals.html
Terry S. Singeltary Sr.
posted by Terry S. Singeltary Sr. at
11:32 AM
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