Friday, February 08, 2013

Behavior of Prions in the Environment: Implications for Prion Biology

Friday, February 08, 2013


Behavior of Prions in the Environment: Implications for Prion Biology


Behavior of Prions in the Environment: Implications for Prion Biology


•Shannon L. Bartelt-Hunt mail,


* E-mail: (SB); (JB) Affiliation: Department of Civil Engineering, University of Nebraska-Lincoln, Peter Kiewit Institute, Omaha, Nebraska, United States of America X


•Jason C. Bartz mail


Citation: Bartelt-Hunt SL, Bartz JC (2013) Behavior of Prions in the Environment: Implications for Prion Biology. PLoS Pathog 9(2): e1003113. doi:10.1371/journal.ppat.1003113 Editor: Heather True-Krob, Washington University School of Medicine, United States of America


Published: February 7, 2013


Copyright: © 2013 Bartelt-Hunt, Bartz. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Funding: This work was supported by the National Science Foundation, CBET-1149242, (S. Bartelt-Hunt) and the National Center for Research Resources, P20 RR0115635-6, C06 RR17417-01 and G200RR024001, (J. Bartz). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.


Competing interests: The authors have declared that no competing interests exist.


Emergence of Prion Diseases


Prion diseases are infectious, potentially zoonotic neurodegenerative diseases of animals including humans that are inevitably fatal and are caused by prions. Prions are comprised of a misfolded isoform of the normal prion protein, PrPC, into the infectious conformation, PrPSc [1]. Of the known prion diseases, chronic wasting disease (CWD) of deer, elk, and moose is emerging. CWD was first identified in captive deer in the front range of Colorado and Wyoming in the 1960s and has since been identified in captive and free-ranging cervids in 20 states, two Canadian provinces, and South Korea (for latest disease distribution please see​tion/chronic_wasting_disease/index.jsp). While there is evidence of the spread of CWD along known cervid home ranges, the mechanism underlying the emergence of CWD in geographically isolated areas is not understood. The prevalence of CWD within an affected population is generally lower than 5%; however, there are reports of incidence rates that approach 50%. Transmission of CWD can occur horizontally or through CWD-contaminated environments, but the relative contribution of each mode in the overall transmission of CWD is unknown [2]. Since effective control measures are not available, it is likely that CWD will continue to spread in North America. The effect of this on the well-being of the cervid population and the risk of transmission to other species is not known.


Prions Are Released into the Environment and Remain Infectious


It has long been observed that indirect lateral transmission of scrapie can occur, and recent evidence also demonstrates indirect lateral transmission of CWD [3]. One factor influencing the environmental transmission of prion diseases is the long-term survival of prions in the environment. Epidemiological studies indicate numerous instances of scrapie recurrence upon reintroduction of animals on farms previously exposed to scrapie. Scrapie recurrence was documented following fallow periods of 1–16 years [4], and pastures can retain infectious CWD prions at least 2 years after exposure [5]. Prions are shed from diseased hosts in a diverse set of biologic matrices, including feces, urine, saliva, blood, skin, milk, placenta, and nasal mucus. A comprehensive review of prion shedding was conducted by Gough and Maddison [6]. Prion shedding can occur many months prior to clinical manifestation of the disease [7]. Prions also enter the environment after decomposition of diseased animal carcasses [5]. The disposal of diseased cattle during bovine spongiform encephalopathy (BSE) outbreaks, both in the past and in potential future disposal events, serves as another environmental source of prions. Uptake of prions to naïve hosts can occur via ingestion or inhalation of contaminated material, although the routes of natural exposure remain uncertain [8]. Recently, scrapie and CWD prions have been detected in environmental samples by protein misfolding cyclic amplification (PMCA). One of two water samples collected from a CWD-endemic area in Colorado was determined to be positive for CWD [9]. Maddison et al. [10] detected scrapie prions on swabs collected from metal, plastic, and wooden surfaces on a scrapie-endemic farm. In the Maddison et al. [10] study, it is not clear whether the scrapie prions associated with the surfaces were co-transported via soil or dust. To our knowledge, no study has investigated the occurrence of CWD or scrapie prions in soil samples collected from areas with known incidence of prion disease.


In the Environment, Prions Can Bind to Soil


Prions shed into the environment will interact with soil. Given the close contact that animals, especially ruminants, have with soil through routine behaviors, including ingestion of soil via feeding and mineral supplementation, there is significant opportunity for transmission of prions via soil. Prions appear to have an affinity for quartz sands and soils and a particularly strong affinity for clay minerals [11]. The biological matrix that prions enter the environment (e.g., urine versus animal carcass) influences the kinetics of prion sorption to soil. Prions sorb to soil more slowly in complex biological matrices compared to prions in simple matrices, likely due to competitive interactions [12]. In addition, the kinetics of PrPSc binding to soil can be influenced by the prion strain [13]. Sorbed prions are resistant to desorption via detergent and chaotropic treatments. As with other proteins, prion sorption is most likely a combination of electrostatic attraction and hydrophobic interactions. Studies using recombinant prions have identified electrostatic attraction between positively charged peptides and negatively charged mineral surfaces as the most significant adsorption mechanisms [14]. Because the N-terminal domain of the prion protein is known to be flexibly disordered and contains a high number of positively charged amino acids, it may play a significant role in electrostatic attraction to negatively charged mineral surfaces. The N-terminal domain is lost upon desorption of PrPSc from clay, but it is not needed for prion adsorption or infectivity [11]. Recombinant PrP has a high affinity for organic matter, equal to or greater than that calculated for mineral surfaces [11]. The three-dimensional structure of PrPSc remains unknown; therefore, it is a challenge to model the specific mechanisms that are significant in PrPSc adsorption to soil. PrPSc is aggregated, and changes in the aggregation state could occur with soil binding, potentially affecting infectivity. One study did find that recPrP does not form β-sheets or self-aggregate when adsorbed to clay [14]. More must be done to determine what conformational changes occur to PrPSc when it binds to soil or minerals and how these changes affect agent survival and infectivity.


The Biologic Properties of Prions Can Be Altered by Attachment to Soil


The biologic properties of the prion protein, including conversion activity and infectivity, can be influenced by attachment to soil particles. Adsorption of CWD PrPSc to soil reduces prion conversion activity via PMCA [15]. The observed decrease in the ability of prions to convert upon binding to certain soils could be due to a number of factors, including conformational changes in PrPSc structure, interference with PrPC/PrPSc interactions, or a change in PrPSc stability that may occur upon binding to soil. Several studies have investigated the role of soil on prion infectivity. Johnson et al. [16] investigated the infectivity of the hyper strain of transmissible milk encephalopathy (HY TME) bound to montmorillonite (Mte) clay particles via intracerebral inoculation. Bioassay results demonstrated a 10-day decrease in incubation period for PrPSc-Mte complexes when compared to PrPSc inocula without Mte. A second study investigating infectivity of PrPSc bound to Mte via oral routes also demonstrated an increase in infectivity relative to clay-free controls [17]. Saunders et al. [15] conducted bioassay experiments using HY TME PrPSc bound to a silty clay loam soil and demonstrated a 14-day extension in incubation period and a 1.3 log reduction in titer, as determined by end point dilution, for soil-bound HY TME prions. This data is consistent with the calculated decrease in PMCA conversion efficiency for soil-bound HY TME PrPSc. The discrepancies between observed differences in soil-bound prion infectivity may be explained by differences in experimental design, such as preparation of PrPSc inocula. Most importantly, all of these studies consistently demonstrate that prions sorbed to soil remain highly infectious and that binding to soil can alter prion infectivity.


The Impact of the Environment on Prion Disease Transmission


The basic parameters of prion environmental interactions are only beginning to be described, and the effect of these interactions on prion transmission and pathogenesis are poorly understood. As shown in Figure 1, the interaction of prions in the environment is complex and must include consideration of the route of introduction for prions to the environment as well as the effects of soil properties and prion strain on prion interaction with soil. For example, the matrix of prion entry into the environment can influence the kinetics of prion binding to soil. Once bound to soil, prions do not readily disassociate from the soil particle and remain highly infectious. The implications of these important observations are that prions immobilized to soil may persist at the surface where transmission to a naïve host would be more likely to occur. Consistent with these observations, an increased incidence of CWD corresponds with geographic regions with soil types that have a high affinity to bind prions [18]. There is strong evidence for the existence of multiple strains of scrapie, and recent studies suggest that more than one strain of CWD exists [19]. Strain-specific interactions with the environment may result in preferential selection of strains that have properties that favor environmental persistence and transmission.


Figure 1. Factors influencing horizontal transmission of prion disease in the environment. doi:10.1371/journal.ppat.1003113.g001




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We sincerely apologize to our colleagues who we could not cite due to limitations in the number of references.




1.Prusiner SB (1982) Novel proteinaceous infectious particles cause scrapie. Science 216: 136–144. doi: 10.1126/science.6801762. Find this article online 2.Mathiason CK, Hays SA, Powers J, Hayes-Klug J, Langenberg J, et al. (2009) Infectious prions in pre-clinical deer and transmission of chronic wasting disease solely by environmental exposure. PLoS ONE 4: e5916 doi:10.1371/journal.pone.0005916.. 3.Saunders SE, Bartelt-Hunt SL, Bartz JC (2012) Chronic wasting disease: occurrence, transmission and zoonotic potential. Emerg Infect Dis 18: 369–376. doi: 10.3201/eid1803.110685. Find this article online 4.Georgsson G, Sigurdarson S, Brown P (2006) Infectious agent of sheep scrapie may persist in the environment for at least 16 years. J Gen Virol 87: 3737–3740. doi: 10.1099/vir.0.82011-0. Find this article online 5.Miller MW, Williams ES, Hobbs NT, Wolfe LL (2004) Environmental sources of prion transmission in mule deer. Emerg Infect Dis 10: 1003–1006. doi: 10.3201/eid1006.040010. Find this article online 6.Gough KC, Maddison BC (2010) Prion transmission: prion excretion and occurrence in the environment. Prion 4: 275–282. doi: 10.4161/pri.4.4.13678. Find this article online 7.Tamguney G, Miller MW, Wolfe LL, Sirochman TM, Glidden DV, et al. (2009) Asymptomatic deer excrete infectious prions in faeces. Nature 461: 529–532. Find this article online 8.Sigurdson CJ, Williams ES, Miller MW, Spraker TR, O'Rourke KI, et al. (1999) Oral transmission and early lymphoid tropism of chronic wasting disease PrPres in mule deer fawns (Odocoileus hemionus). J Gen Virol 80: 2757–2764. Find this article online 9.Nichols TA, Pulford B, Wyckoff AC, Meyerett C, Michel B, et al. (2009) Detection of protease-resistant cervid prion protein in water from a CWD-endemic area. Prion 3: 171–183. doi: 10.4161/pri.3.3.9819. Find this article online 10.Maddison BC, Baker CA, Terry LA, Bellworthy SJ, Thorne L, et al. (2010) Environmental sources of scrapie prions. J Virol 84: 11560–11562. doi: 10.1128/JVI.01133-10. Find this article online 11.Saunders SE, Bartelt-Hunt SL, Bartz JC (2008) Prions in the environment: Occurrence, fate, and mitigation. Prion 2: 162–169. doi: 10.4161/pri.2.4.7951. Find this article online 12.Saunders SE, Bartz JC, Bartelt-Hunt SL (2009) Prion protein adsorption to soil in a competitive matrix is slow and reduced. Environ Sci Technol 43: 7728–7733. doi: 10.1021/es901385t. Find this article online 13.Saunders SE, Bartz JC, Bartelt-Hunt SL (2009) Influence of prion strain on prion protein adsorption to soil in a competitive matrix. Environ Sci Technol 43: 5242–5248. doi: 10.1021/es900502f. Find this article online 14.Revault M, Quiquampoix H, Baron MH, Noinville S (2005) Fate of prions in soil: Trapped conformation of full-length ovine prion protein induced by adsorption on clays. Biochim et Biophys Acta 1724: 367–374. doi: 10.1016/j.bbagen.2005.05.005. Find this article online 15.Saunders SE, Shikiya RA, Langenfeld K, Bartelt-Hunt SL, Bartz JC (2011) Replication efficiency of soil-bound prions varies with soil type. J Virol 85: 5476–5482. doi: 10.1128/JVI.00282-11. Find this article online 16.Johnson CJ, Phillips KE, Schramm PT, McKenzie D, Aiken JM, et al. (2006) Prions adhere to soil minerals and remain infectious. PLoS Pathog 2: e32 doi:10.1371/journal.ppat.0020032.. 17.Johnson CJ, Pedersen JA, Chappell RJ, McKenzie D, Aiken JM (2007) Oral transmissibility of prion disease Is enhanced by binding of soil particles. PLoS Pathog 3: e93 doi:10.1371/journal.ppat.0030093.. 18.Walters WD, Walsh DP, Farnsworth ML, Winkelman DL, Miller MW (2011) Soil clay content underlies prion infection odds. Nature Comm 2: 200. Find this article online 19.Angers RC, Kang HE, Napier D, Browning SR, Seward T, et al. (2010) prion strain mutation determined by prion protein conformational compatibility and primary structure. Science 328: 1154–1158. doi: 10.1126/science.1187107. Find this article online



WHAT about the CWD TSE prion in the soil, blowing in the wind to potentially contaminant land far, far, away ???


 Understanding Microbes Blowing in the Wind


 By Dennis O'Brien


 February 6, 2013


 With help from a wind tunnel and the latest DNA technology, U.S. Department of Agriculture (USDA) scientists are shedding light on the travel patterns of microbes in soils carried off by strong winds. The work has implications for soil health and could lead to management practices that minimize the damage to soils caused by wind erosion.


 Wind erosion is an emerging issue in soil conservation efforts. Agricultural Research Service (ARS) scientists have been studying wind-eroded soils since the 1930s, but few studies have focused on the effects of wind on the bacteria, fungi, and protozoa in the soil. ARS is USDA's chief intramural scientific research agency.


 Researchers see an increasing need to focus on pathogens and agriculturally important bacteria carried in dust. ARS soil scientist Veronica Acosta-Martinez, with the agency's Wind Erosion and Water Conservation Unit in Lubbock, Texas, focused on bacterial populations that could be classified by DNA sequencing. She worked with Terrence Gardner, a visiting scientist from Alabama A&M University.


 Researchers collected airborne dust and samples of a type of organic soil susceptible to wind erosion from fields where potatoes, beets and onions had grown a few years earlier and exposed them to windy conditions using a portable wind tunnel. They characterized the bacteria they found in both the "source soils" and the wind-eroded sediments, focusing on types of bacteria associated with coarse particles and on the types associated with fine dust particles.


 They classified the bacteria found in each type of soil and wind-eroded sediment using pyrosequencing, a process that allowed them to identify up to 100 times more DNA in each sample than they would have detected with traditional methods. The study results, published online in the Journal of Environmental Quality, showed that certain types of bacteria, known as Bacteroidetes, were more predominant in the fine dust. Other types, known as Proteobacteria, were more predominant in coarse sediments.


 Studies have shown that Bacteroidetes resist desiccation and thus can survive in extreme conditions when carried long distances. The fact that Proteobacteria were associated with coarse eroded sediments, which travel shorter distances, may explain how soils can retain important qualities despite damaging winds. Proteobacteria play an important role in carbon and nitrogen cycling, and their fate in dust storms will be the focus of future research, according to Acosta-Martinez.


 Read more about this research in the February 2013 issue of Agricultural Research magazine.





 Environmental Sources of Prion Transmission in Mule Deer


 Michael W. Miller,* Elizabeth S. Williams,† N. Thompson Hobbs,‡ and Lisa L. Wolfe*


Whether transmission of the chronic wasting disease (CWD) prion among cervids requires direct interaction with infected animals has been unclear. We report that CWD can be transmitted to susceptible animals indirectly, from environments contaminated by excreta or decomposed carcasses. Under experimental conditions, mule deer (Odocoileus hemionus) became infected in two of three paddocks containing naturally infected deer, in two of three paddocks where infected deer carcasses had decomposed in situ ≈1.8 years earlier, and in one of three paddocks where infected deer had last resided 2.2 years earlier. Indirect transmission and environmental persistence of infectious prions will complicate efforts to control CWD and perhaps other animal prion diseases.





Research Article


Infectious Prions in Pre-Clinical Deer and Transmission of Chronic Wasting Disease Solely by Environmental Exposure




 Key to understanding the epidemiology and pathogenesis of prion diseases, including chronic wasting disease (CWD) of cervids, is determining the mode of transmission from one individual to another. We have previously reported that saliva and blood from CWD-infected deer contain sufficient infectious prions to transmit disease upon passage into naïve deer.


 Here we again use bioassays in deer to show that blood and saliva of pre-symptomatic deer contain infectious prions capable of infecting naïve deer and that naïve deer exposed only to environmental fomites from the suites of CWD-infected deer acquired CWD infection after a period of 15 months post initial exposure.


 These results help to further explain the basis for the facile transmission of CWD, highlight the complexities associated with CWD transmission among cervids in their natural environment, emphasize the potential utility of blood-based testing to detect pre-clinical CWD infection, and could augur similar transmission dynamics in other prion infections.




 In summary, the results reported here reconfirm that blood and saliva are sources of infectious CWD prions, consistent with previous findings [27], and further support a mechanism for efficient CWD transmission in nature. We also show that infectious prions shed into the environment by CWD+ deer are sufficient to transmit the disease to naïve deer in the absence of direct animal-to-animal contact. These observations reinforce the exposure risk associated with body fluids, excreta, and all tissues from CWD+ cervids and suggest that similar dynamics may exist in other prion infections.



March 2012


 Indirect Environmental Transmission Environmental transmission of the CWD agent was reported in studies demonstrating that an infected deer carcass left in a pasture for 2 years could transmit the agent to immunologically naive deer (17). Exposure of naive deer to pasture previously inhabited by an infected deer also led to CWD transmission, as did cohabitation of naive and infected deer (17). Naive deer exposed to water, feed buckets, and bedding used by CWD-infected deer contracted the disease (18).


 Epidemiologic modeling suggests that indirect environmental routes of CWD transmission also play a major role in transmission (8). Environmental transmission of scrapie is well documented, and scrapie prions may remain infectious after years in the environment (19,20; S.E. Saunders, unpub. data). Nevertheless, environmental transmission of scrapie may be less efficient than transmission by direct contact (19). Conversely, the relative efficiency of CWD transmission by direct contact versus indirect, environmental routes remains unclear, but evidence suggests environmental transmission may be a major mechanism (8). The proportion of transmission by direct versus indirect routes may vary not only between captive and free-ranging cervid populations, but also among cervid species and free-ranging habitats and ecosystems. Transmission dynamics may also vary over time as CWD prevalence and ecosystem residence times continue to increase (8).






Salivary prions in sheep and deer


 Gültekin Tamgüney,1,2,† Jürgen A. Richt,3,8 Amir N. Hamir,3,9 Justin J. Greenlee,3 Michael W. Miller,4 Lisa L. Wolfe,4 Tracey M. Sirochman,4 Alan J. Young,5 David V. Glidden,6 Natrina L. Johnson,1 Kurt Giles,1,2 Stephen J. DeArmond1,7 and Stanley B. Prusiner1,2,*


 1Institute for Neurodegenerative Diseases; San Francisco, CA USA; 2Department of Neurology; University of California, San Francisco, CA USA; 3National Animal Disease Center; ARS-USDA; Ames, IA USA; 4Colorado Division of Wildlife; Wildlife Research Center; Fort Collins, CO USA; 5Department of Veterinary Science; South Dakota State University; Brookings, SD USA; 6Departments of Epidemiology and Biostatistics; University of California, San Francisco, CA USA; 7Department of Pathology; University of California; San Francisco, CA USA; 8College of Veterinary Medicine; Kansas State University, Manhattan, KS USA; 9MD Anderson Cancer Center; Houston, TX USA †Current address: German Center for Neurodegenerative Diseases; Bonn, Germany


 Key words: scrapie, chronic wasting disease, saliva, horizontal transmission, titers


 Scrapie of sheep and chronic wasting disease (CWD) of cervids are transmissible prion diseases. Milk and placenta have been identified as sources of scrapie prions but do not explain horizontal transmission. In contrast, CWD prions have been reported in saliva, urine and feces, which are thought to be responsible for horizontal transmission. While the titers of CWD prions have been measured in feces, levels in saliva or urine are unknown. Because sheep produce ~17 L/day of saliva and scrapie prions are present in tongue and salivary glands of infected sheep, we asked if scrapie prions are shed in saliva. We inoculated transgenic (Tg) mice expressing ovine prion protein, Tg(OvPrP) mice, with saliva from seven Cheviot sheep with scrapie. Six of seven samples transmitted prions to Tg(OvPrP) mice with titers of -0.5 to 1.7 log ID50 U/ml. Similarly, inoculation of saliva samples from two mule deer with CWD transmitted prions to Tg(ElkPrP) mice with titers of -1.1 to -0.4 log ID50 U/ml. Assuming similar shedding kinetics for salivary prions as those for fecal prions of deer, we estimated the secreted salivary prion dose over a 10-mo period to be as high as 8.4 log ID50 units for sheep and 7.0 log ID50 units for deer. These estimates are similar to 7.9 log ID50 units of fecal CWD prions for deer. Because saliva is mostly swallowed, salivary prions may reinfect tissues of the gastrointestinal tract and contribute to fecal prion shedding. Salivary prions shed into the environment provide an additional mechanism for horizontal prion transmission.



Conclusions. This study documents the first aerosol transmission of CWD in deer. These results further infer that aerosolized prions facilitate CWD transmission with greater efficiency than does oral exposure to a larger prion dose. Thus exposure via the respiratory mucosa may be significant in the facile spread of CWD in deer and perhaps in prion transmission overall.



Conclusion. Transepithelial transport of prions across nasal cavity mucosa begins within minutes of inhalation and can continue for up to 3 h. While M cells appear to transport prions across the follicular associated epithelium, larger amounts of prions are transported between the cells of the respiratory and olfactory epithelia, where they immediately enter the lymphatic vessels in the lamina propria. Thus, inhaled prions can be spread via lymph draining the nasal cavity and have access to somatic and autonomic nerves in the lamina propria of the nasal cavity. The increased efficiency of the nasal cavity route of infection compared with the oral route may be due to the rapid and prolonged transport of prions between cells of the respiratory and olfactory epithelia.



Now that these experiments are completed we conclude that TSE infectivity is likely to survive burial for long periods of time with minimal loss of infectivity and restricted movement from the site of burial. These experiments emphasize that the environment is a viable reservoir for retaining large quantities of TSE infectivity, and reinforce the importance of risk assessment when disposing of this type of infectious material.



Friday, December 14, 2012


DEFRA U.K. What is the risk of Chronic Wasting Disease CWD being introduced into Great Britain? A Qualitative Risk Assessment October 2012



Monday, September 17, 2012


Rapid Transepithelial Transport of Prions Following Inhalation



Monday, November 26, 2012


Aerosol Transmission of Chronic Wasting Disease in White-tailed Deer



Monday, November 26, 2012


Rapid Transepithelial Transport of Prions following Inhalation



Enzymatic Digestion of Chronic Wasting Disease Prions Bound to Soil


S A M U E L E . S A U N D E R S , † J A S O N C . B A R T Z , ‡ K U R T C . V E R C A U T E R E N , § A N D S H A N N O N L . B A R T E L T - H U N T * , †


Department of Civil Engineering, Peter Kiewit Institute, University of NebraskasLincoln, Omaha, Nebraska 68588, Department of Medical Microbiology and Immunology, Creighton University, Omaha, Nebraska 68178, and USDA Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center, Fort Collins, Colorado 80521 Received November 19, 2009. Revised manuscript received April 5, 2010. Accepted April 24, 2010.


 Chronic wasting disease (CWD) and sheep scrapie can be transmitted via indirect environmental routes, and it is known that soil can serve as a reservoir of prion infectivity. Given the strong interaction between the prion protein (PrP) and soil, we hypothesized that binding to soil enhances prion resistance to enzymatic digestion, thereby facilitating prion longevity in the environment and providing protection from host degradation. We characterized the performance of a commercially available subtilisin enzyme, Prionzyme, to degrade soil-bound and unbound CWD and HY TME PrP as a function of pH, temperature, and treatment time. The subtilisinenzymeeffectively degraded PrP adsorbed to a wide range of soils and soil minerals below the limits of detection. Signal loss occurred rapidly at high pH (12.5) and within 7 days under conditions representative of the natural environment (pH 7.4, 22 °C). We observednoapparent difference inenzymeeffectivenessbetween bound and unbound CWD PrP. Our results show that although adsorbed prions do retain relative resistance to enzymatic digestion compared with other brain homogenate proteins, they can be effectively degraded when bound to soil. Our results also suggest a topical application of a subtilisin enzyme solution may be an effective decontamination method to limit disease transmission via environmental “hot spots” of prion infectivity. see full text study here ;




CWD TSE prion disease survives ashing to 600 degrees celsius, that’s around 1112 degrees farenheit.


you cannot cook the CWD TSE prion disease out of meat.


you can take the ash and mix it with saline and inject that ash into a mouse, and the mouse will go down with TSE.


Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel Production as well.


the TSE prion agent also survives Simulated Wastewater Treatment Processes.


IN fact, you should also know that the CWD TSE Prion agent will survive in the environment for years, if not decades.


you can bury it and it will not go away.


CWD TSE agent is capable of infected your water table i.e. Detection of protease-resistant cervid prion protein in water from a CWD-endemic area.


it’s not your ordinary pathogen you can just cook it out and be done with.


that’s what’s so worrisome about Iatrogenic mode of transmission, a simple autoclave will not kill this TSE prion agent.


New studies on the heat resistance of hamster-adapted scrapie agent: Threshold survival after ashing at 600°C suggests an inorganic template of replication


Paul Brown*,dagger , Edward H. RauDagger , Bruce K. Johnson*, Alfred E. Bacote*, Clarence J. Gibbs Jr.*, and D. Carleton Gajdusek§ * Laboratory of Central Nervous System Studies, National Institute of Neurological Disorders and Stroke, and Dagger Environmental Protection Branch, Division of Safety, Office of Research Services, National Institutes of Health, Bethesda, MD 20892; and § Institut Alfred Fessard, Centre National de la Recherche Scientifique, 91198 Gif sur Yvette, France Contributed by D. Carleton Gajdusek, December 22, 1999


 see full text:



Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel Production


Cathrin E. Bruederle,1* Robert M. Hnasko,1 Thomas Kraemer,2 Rafael A. Garcia,3 Michael J. Haas,3 William N. Marmer,3 and John Mark Carter1 1USDA-ARS WRRC, Foodborne Contaminants Research Unit, Albany, California, United States of America 2Forensic Toxicology, Institute of Legal Medicine, Saarland University, Homburg/Saar, Germany 3USDA-ARS ERRC, Fats, Oils and Animal Coproducts Research Unit, Wyndmoor, Pennsylvania, United States of America Neil Mabbott, EditorUniversity of Edinburgh, United Kingdom *



Wednesday, October 14, 2009


 Detection of protease-resistant cervid prion protein in water from a CWD-endemic area


 T.A. Nichols,1,2 Bruce Pulford,1 A. Christy Wyckoff,1,2 Crystal Meyerett,1 Brady Michel,1 Kevin Gertig,3 Edward A. Hoover,1 Jean E. Jewell,4 Glenn C. Telling5 and Mark D. Zabel1,*


 1Department of Microbiology, Immunology and Pathology; College of Veterinary Medicine and Biomedical Sciences; Colorado State University; Fort Collins, CO USA; 2National Wildlife Research Center; Wildlife Services; United States Department of Agriculture; Fort Collins, CO USA; 3Fort Collins Utilities; Fort Collins; CO USA; 4Department of Veterinary Sciences; Wyoming State Veterinary Laboratory; University of Wyoming; Laramie, WY USA; 5Department of Microbiology, Immunology, Molecular Genetics and Neurology; Sanders Brown Center on Aging; University of Kentucky; Lexington, KY USA




The data presented here demonstrate that sPMCA can detect low levels of PrPCWD in the environment, corroborate previous biological and experimental data suggesting long term persistence of prions in the environment2,3 and imply that PrPCWD accumulation over time may contribute to transmission of CWD in areas where it has been endemic for decades. This work demonstrates the utility of sPMCA to evaluate other environmental water sources for PrPCWD, including smaller bodies of water such as vernal pools and wallows, where large numbers of cervids congregate and into which prions from infected animals may be shed and concentrated to infectious levels.



snip...see more here ;


Monday, August 8, 2011


Susceptibility of Domestic Cats to CWD Infection


Oral.29: Susceptibility of Domestic Cats to CWD Infection




for those interested, you can see the program here ;


PRION 2011


PrioNet Canada and the Alberta Prion Research Institute are proud to co-host the world’s largest international prion research conference, PRION 2011, in Montreal, Quebec from May 16-19. This is the first time this conference is being presented outside of Europe. This international PRION 2011 congress will follow in the same tradition as past PRION conferences and aims to welcome over 600 attendees from around the world. PRION 2011 anticipates over 55 speakers and will include an outstanding list of plenary lectures, special sessions, “hot topic” panels, networking activities, and poster presentations.


Prion diseases know no borders, and this congress represents the one annual event to bring together experts from around the world to discuss a broad spectrum of topics, from surveillance and control, to prion structure and function, to diagnostics and therapeutics, ultimately with the goal to enhance the pace of prion research to mitigate the negative impacts of prion disease on society. This meeting will also cover the new connections between prion diseases and other human misfolding protein diseases such as Alzheimer’s, Parkinson’s and others. Prion-like propagation of protein misfolding will be one of four special themes of the meeting.


We look forward to your participation!


The PRION 2011 Steering Committee



Thursday, February 17, 2011


Environmental Sources of Scrapie Prions



Saturday, May 14, 2011


Modeling Routes of Chronic Wasting Disease Transmission: Environmental Prion Persistence Promotes Deer Population Decline and Extinction



Tuesday, December 18, 2012


A Growing Threat How deer breeding could put public trust wildlife at risk



Friday, November 09, 2012


Chronic Wasting Disease CWD in cervidae and transmission to other species



Sunday, November 11, 2012


Susceptibilities of Nonhuman Primates to Chronic Wasting Disease November 2012



Friday, December 14, 2012


Susceptibility Chronic Wasting Disease (CWD) in wild cervids to Humans 2005 - December 14, 2012



PRION 2010


International Prion Congress: From agent to disease September 8–11, 2010 Salzburg, Austria


PRION 2010 is the top Global Annual TSE Conference in prion research, following a sequence of PRION meetings that were originally organized by the EU Network of Excellence NeuroPrion. In this proud tradition, PRION 2010 covers all aspects of this fascinating scientific area. PRION 2010 is a meeting of greatest interest for neuroscientists, protein structural biologists, geneticists, medical specialists including neurologists, neuropathologists, hygiene experts and blood product providers, veterinarians, epidemiologists, laboratory technicians, industry developers, risk assessors and managers. An outstanding list of Plenary Lecture, Symposia and Workshop Speakers is complemented by the plethora of original input from Poster Presentations. Special consideration is given this year to two areas of major interest: the renewed discussion about the zoonotic potential of animal prion diseases, given the emergence of atypical BSE and scrapie strains, and the breakthrough work on synthetic prions by several groups simultaneously.






 Survival and Limited Spread of TSE Infectivity after Burial


 Karen Fernie, Allister Smith and Robert A. Somerville The Roslin Institute and R(D)SVS; University of Edinburgh; Roslin, Scotland UK

Scrapie and chronic wasting disease probably spread via environmental routes, and there are also concerns about BSE infection remaining in the environment after carcass burial or waste 3disposal. In two demonstration experiments we are determining survival and migration of TSE infectivity when buried for up to five years, as an uncontained point source or within bovine heads. Firstly boluses of TSE infected mouse brain were buried in lysimeters containing either sandy or clay soil. Migration from the boluses is being assessed from soil cores taken over time. With the exception of a very small amount of infectivity found 25 cm from the bolus in sandy soil after 12 months, no other infectivity has been detected up to three years. Secondly, ten bovine heads were spiked with TSE infected mouse brain and buried in the two soil types. Pairs of heads have been exhumed annually and assessed for infectivity within and around them. After one year and after two years, infectivity was detected in most intracranial samples and in some of the soil samples taken from immediately surrounding the heads. The infectivity assays for the samples in and around the heads exhumed at years three and four are underway. These data show that TSE infectivity can survive burial for long periods but migrates slowly. Risk assessments should take into account the likely long survival rate when infected material has been buried.


 The authors gratefully acknowledge funding from DEFRA.




 Enzymatic Digestion of Chronic Wasting Disease Prions Bound to Soil


 Samuel E. Saunders,1 Jason C. Bartz,2 Kurt C. Vercauteren3 and Shannon L. Bartelt-Hunt1 1Department of Civil Engineering; University of Nebraska-Lincoln; Peter Kiewit Institute; Omaha, Nebraska USA; 2Department of Medical Microbiology and Immunology; Creighton University; Omaha, Nebraska USA; 3USDA; Animal and Plant Health Inspection Service; Wildlife Services; National Wildlife Research Center; Fort Collins, CO USA


 Chronic wasting disease (CWD) and sheep scrapie can be transmitted via indirect environmental routes, and it is known that soil can serve as a reservoir of prion infectivity. Given the strong interaction between the prion protein (PrP) and soil, we hypothesized that binding to soil enhances prion resistance to enzymatic digestion, thereby facilitating prion longevity in the environment and providing protection from host degradation. We characterized the performance of a commercially available subtilisin enzyme, the Prionzyme, to degrade soil-bound and unbound CWD and HY TME PrP as a function of pH, temperature, and treatment time. The subtilisin enzyme effectively degraded PrP adsorbed to a wide range of soils and soil minerals below the limits of detection. Signal loss occurred rapidly at high pH (12.5) and within 7 d under conditions representative of the natural environment (pH 7.4, 22°C). Serial PMCA of treated soil samples suggests a greater than 6-log decrease in infectious titer compared with controls. We observed no apparent difference in enzyme effectiveness between bound and unbound CWD PrP. Our results show that although adsorbed prions do retain relative resistance to enzymatic digestion compared with other brain homogenate proteins, they can be effectively degraded when bound to soil. Our results also suggest a topical application of a subtilisin enzyme solution may be an effective decontamination method to limit disease transmission via environmental ‘hot spots’ of prion infectivity.




 Degradation of Pathogenic Prion Protein and Prion Infectivity by Lichens


 Christopher J. Johnson,1 James P. Bennett,1 Steven M. Biro,1,2 Cynthia M. Rodriguez,1,2 Richard A. Bessen3 and Tonie E. Rocke1


 1USGS National Wildlife Health Center; 2Department of Bacteriology; University of Wisconsin, Madison; 3Department of Veterinary Molecular Biology; Montana State University; Bozeman, MT USA


 Key words: prion, lichen, bioassay, protease, degradation


 Few biological systems have been identified that degrade the transmissible spongiform encephalopathy (TSE)-associated form of the prion protein (PrPTSE) and TSE infectivity. Stability of the TSE agent allows scrapie and chronic wasting disease agents to persist in the environment and cause disease for years. Naturally-occurring or engineered processes that reduce infectivity in the environment could aid in limiting environmental TSE transmission. We have previously identified that species of at least three lichens, unusual, symbiotic organisms formed from a fungus and photosynthetic partner, contain a serine protease capable of degrading PrPTSE under gentle conditions. We tested the hypothesis that lichen extracts from these three species reduce TSE infectivity by treating infected brain homogenate with extracts and examining infectivity in mice. We found lichen extracts diminished TSE infectious titer by factors of 100 to 1,000 and that reductions in infectivity were not well-correlated with the extent of PrPTSE degradation observed by immunoblotting. For example, treatment of brain homogenate with Cladonia rangiferina extract caused <100-fold activity="" after="" agents.="" also="" and="" anti-prion="" but="" characterization="" cladonia="" closely="" clusters="" comparison="" data="" decrease="" degradation="" degrade="" div="" do="" extract="" favors="" focus="" fold="" for="" forms="" genera="" has="" immunoreactivity="" in="" indicate="" infectious="" infectivity="" known="" lichen="" more="" necessarily="" not="" of="" on="" or="" our="" phylogeny="" prion-degrading="" protease="" prp="" prptse.="" prptse="" reduction="" related="" remaining="" rendered="" searches="" some="" species-specificity="" species="" suggesting="" that="" the="" those="" to="" treatment="" uninfectious="" usnea="" was="" which="" with="" within="" yielded="">




 The Anti-prion Activity of Soil Organic Compounds Humic and Fulvic Acids


 Joanna Narkiewicz,1,2 Ai H.N. Tran,1 Gabriele Giachin,1 Liviana Leita2 and Giuseppe Legname1, 1Neurobiology Sector; Scuola Internazionale Superiore di Studi Avanzati; International School for Advanced Studies; Bonomea, Trieste Italy; 2Agricultural Research Council (CRA); Research Centre for Soil-Plant System; Trieste, Gorizia Italy


 A notable feature of prion diseases, as scrapie in sheep and chronic wasting disease in mule deer and elk, is horizontal transmission between grazing animals, suggesting that contaminated environment may contribute significantly to disease transmission. Increasing evidence suggests that soil may present natural reservoir of prion infectivity. Recent studies have shown that prions may persist in contaminated soil and remain infectious for years. As the mechanism of prion retention and persistence in soil is unknown, it is necessary to understand which soil components may interact with prions and thus contribute to disease transmission. Several reports indicate that prion have potential to interact with soil minerals, however the contribution of soil organic fraction in adsorption to prions has been neglected. Here, we present strong evidence for soil humic substances (HS) interaction with prions. We show that two HS, classified as humic and fulvic acids, interact with recombinant prion proteins in vitro. Moreover, we show that both HS possess anti-prion activity, both in vivo and in vitro. Both compounds induced elimination of PrPSc from chronically scrapie-infected GT1 mouse hypothalamic cells (ScGT1) in a dose-dependent manner. ScGT1 cells treatment with HS at concentration of 20mg/mL eliminated more than 95% of PrPSc and did not affect cell viability. Moreover, both HS induced inhibition of prion fibril formation in vitro, as determined by thioflavin T assay. Our results suggest that HS may contribute significantly to prion inactivation in natural soil environments.




 Detection of PrPCWD in Rocky Mountain Elk Feces Using Protein Misfolding Cyclic Amplification


 Bruce E Pulford,1 Terry Spraker,1 Jenny Powers,2 Margaret Wild2 and Mark D. Zabel1 1Department of Microbiology; Immunology and Pathology; College of Veterinary Medicine and Biomedical Sciences; Colorado State University; 2Biological Resource Management Division; United States National Park Service; CO, USA


 Key words: CWD, feces, PMCA, elk


 Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy affecting cervids, including mule and white-tailed deer (Odocoileus hemionus and virginianus), elk (Cervus elaphus nelsoni) and moose (Alces alces shirasi). The method of CWD transmission between hosts is unclear, though there is evidence that feces excreted by infected animals may play a role. Recently, CWD prions was detected in feces using bioassays in cervidized mice, which took many months to produce results. In this study, we use a more rapid procedure, protein misfolding cyclic amplification (PMCA), to test elk feces for the presence of PK-resistant cervid PrP (PrPCWD). Feces were collected from symptomatic and asymptomatic elk in several northern Colorado locations, homogenized, mixed with normal brain homogenate from Tg5037 mice (expressing cervid PrP) and subjected to up to 9 rounds of PMCA (1 round = 40 secs sonication/30 mins at 70% maximum power, 24 hours). Western blots were used to detect PrPCWD using BAR-224 anti-PrP antibody. Rectal and CNS tissue from the elk were IHC-labeled and examined for the presence of PrPCWD. Fecal samples from symptomatic and asymptomatic elk that tested positive by IHC showed characteristic PrPCWD bands on western blots following PMCA. In addition, PMCA detected PrPCWD in 25% of fecal samples from IHC-negative animals. These data suggest that PMCA may (1) prove useful as a non-invasive method to supplement or even replace IHC testing of cervids for CWD, and (2) identify additional asymptomatic carriers of CWD, the prevalence of which may be underestimated using IHC.



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Friday, February 25, 2011


Soil clay content underlies prion infection odds





Wednesday, September 08, 2010







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