ALS-Causing Mutations Significantly Perturb the Self-Assembly and Interaction with Nucleic Acid of the Intrinsically Disordered Prion-Like Domain of TDP-43
Published: January 6, 2016 •DOI: 10.1371/journal.pbio.1002338
TAR-DNA-binding protein-43 (TDP-43) C-terminus encodes a prion-like domain widely presented in RNA-binding proteins, which functions to form dynamic oligomers and also, amazingly, hosts most amyotrophic lateral sclerosis (ALS)-causing mutations. Here, as facilitated by our previous discovery, by circular dichroism (CD), fluorescence and nuclear magnetic resonance (NMR) spectroscopy, we have successfully determined conformations, dynamics, and self-associations of the full-length prion-like domains of the wild type and three ALS-causing mutants (A315E, Q331K, and M337V) in both aqueous solutions and membrane environments. The study decodes the following: (1) The TDP-43 prion-like domain is intrinsically disordered only with some nascent secondary structures in aqueous solutions, but owns the capacity to assemble into dynamic oligomers rich in β-sheet structures. By contrast, despite having highly similar conformations, three mutants gained the ability to form amyloid oligomers. The wild type and three mutants all formed amyloid fibrils after incubation as imaged by electron microscopy. (2) The interaction with nucleic acid enhances the self-assembly for the wild type but triggers quick aggregation for three mutants. (3) A membrane-interacting subdomain has been identified over residues Met311-Gln343 indispensable for TDP-43 neurotoxicity, which transforms into a well-folded Ω-loop-helix structure in membrane environments. Furthermore, despite having very similar membrane-embedded conformations, three mutants will undergo further self-association in the membrane environment. Our study implies that the TDP-43 prion-like domain appears to have an energy landscape, which allows the assembly of the wild-type sequence into dynamic oligomers only under very limited condition sets, and ALS-causing point mutations are sufficient to remodel it to more favor the amyloid formation or irreversible aggregation, thus supporting the emerging view that the pathologic aggregation may occur via the exaggeration of functionally important assemblies. Furthermore, the coupled capacity of TDP-43 in aggregation and membrane interaction may critically account for its high neurotoxicity, and therefore its decoupling may represent a promising therapeutic strategy to treat TDP-43 causing neurodegenerative diseases.
Amyotrophic lateral sclerosis (ALS) is the most prevalent fatal motor neuron disease. It was identified ~140 years ago, but the exact mechanism underlying the disease has still not been well defined. TAR-DNA-binding protein-43 (TDP-43) was identified as the major component of the proteinaceous inclusions present in ~97% ALS and ~45% frontotemporal dementia (FTD) patients, and has also been observed in an increasing spectrum of other neurodegenerative disorders, including Alzheimer disease. The TDP-43 C-terminus is a key domain—it encodes a prion-like domain and, crucially, hosts almost all ALS-causing mutations. Here we have successfully determined the conformations, dynamics, and self-associations of the prion-like domains of both wild type and three ALS-causing mutants in both aqueous solutions and membrane environments. The study suggests that the TDP-43 prion-like domain appears to have a unique energy landscape, which allows the assembly of the wild-type sequence into specific oligomers only under very limited conditions. Intriguingly, ALS-causing point mutations remodel the energy landscape to favor amyloid formation or irreversible aggregation, thus supporting the emerging view that pathologic aggregation may occur via the exaggeration of functionally important assemblies. Furthermore, the coupled capacity of TDP-43 in aggregation and membrane interaction may partly account for its high neurotoxicity; decoupling these may therefore represent a promising therapeutic strategy to treat TDP-43-mediated neurodegenerative diseases.
SNIP...see full text ;
>>> The study suggests that the TDP-43 prion-like domain appears to have a unique energy landscape, which allows the assembly of the wild-type sequence into specific oligomers only under very limited conditions. Intriguingly, ALS-causing point mutations remodel the energy landscape to favor amyloid formation or irreversible aggregation, thus supporting the emerging view that pathologic aggregation may occur via the exaggeration of functionally important assemblies. <<<
please see ;
Wednesday, January 13, 2016
An efficient procedure for removal and inactivation of alpha-synuclein assemblies from laboratory materials
***>>>An efficient procedure for removal and inactivation of alpha-synuclein assemblies from laboratory materials<<<***
***>>> This retrospective study, however, does not definitively exclude the possibility that a-synucleinopathy can transmit between humans. <<<***
An efficient procedure for removal and inactivation of alpha-synuclein assemblies from laboratory materials ???
Effect of heating on the stability of amyloid A (AA) fibrils and the intra- and cross-species transmission of AA amyloidosis
DOI:10.3109/13506129.2015.1095735Saki Ogawaa, Tomoaki Murakamib, Yasuo Inoshimaa & Naotaka Ishiguroa*
Publishing models and article dates explained
Received: 5 May 2015 Accepted: 14 Sep 2015 Published online: 20 Nov 2015 .
Amyloid A (AA) amyloidosis is a protein misfolding disease characterized by extracellular deposition of AA fibrils. AA fibrils are found in several tissues from food animals with AA amyloidosis. For hygienic purposes, heating is widely used to inactivate microbes in food, but it is uncertain whether heating is sufficient to inactivate AA fibrils and prevent intra- or cross-species transmission. We examined the effect of heating (at 60 °C or 100 °C) and autoclaving (at 121 °C or 135 °C) on murine and bovine AA fibrils using Western blot analysis, transmission electron microscopy (TEM), and mouse model transmission experiments. TEM revealed that a mixture of AA fibrils and amorphous aggregates appeared after heating at 100 °C, whereas autoclaving at 135 °C produced large amorphous aggregates. AA fibrils retained antigen specificity in Western blot analysis when heated at 100 °C or autoclaved at 121 °C, but not when autoclaved at 135 °C. Transmissible pathogenicity of murine and bovine AA fibrils subjected to heating (at 60 °C or 100 °C) was significantly stimulated and resulted in amyloid deposition in mice. Autoclaving of murine AA fibrils at 121 °C or 135 °C significantly decreased amyloid deposition. Moreover, amyloid deposition in mice injected with murine AA fibrils was more severe than that in mice injected with bovine AA fibrils. Bovine AA fibrils autoclaved at 121 °C or 135 °C did not induce amyloid deposition in mice. These results suggest that AA fibrils are relatively heat stable and that similar to prions, autoclaving at 135 °C is required to destroy the pathogenicity of AA fibrils. These findings may contribute to the prevention of AA fibril transmission through food materials to different animals and especially to humans.
AA amyloidosis, AA fibrils, Image J software, immunohistochemistry, prion, silver nitrate, transmission electron microscopy, Western blot analysis
***PRION2015 Ft. Collins***
*** P.34: Preliminary study of Alzheimer’s disease transmission to bank vole ***
Guido Di Donato1, Geraldina Riccardi1, Claudia D’Agostino1, Flavio Torriani1, Maurizio Pocchiari2, Romolo Nonno1, Umberto Agrimi1, and Michele Angelo Di Bari1
1Department of Food Safety and Veterinary Public Health Istituto Superiore di Sanit a, Rome, Italy; 2Department of Cellular Biology and Neuroscience; Istituto Superiore di Sanit a, Rome, Italy
Extensive experimental findings indicate that prion-like mechanisms underly the pathogenesis of Alzheimer disease (AD). Transgenic mice have been pivotal for investigating prionlike mechanisms in AD, still these models have not been able so far to recapitulate the complex clinical-pathological features of AD. Here we aimed at investigating the potential of bank vole, a wild-type rodent highly susceptible to prions, in reproducing AD pathology upon experimental inoculation.
Voles were intracerebrally inoculated with brain homogenate from a familial AD patient. Animals were examined for the appearance of neurological signs until the end of experiment (800 d post-inoculation, d.p.i.). Brains were studied by immunohistochemistry for pTau Prion 2015 Poster Abstracts S29 (with AT180 and PHF-1 antibodies) and b-amyloid (4G8).
Voles didn’t show an overt clinical signs, still most of them (11/16) were found pTau positive when culled for intercurrent disease or at the end of experiment. Interestingly, voles culled as early as 125 d.p.i. already showed pTau aggregates. Deposition of pTau was similar in all voles and was characterized by neuropil threads and coiled bodies in the alveus, and by rare neurofibrillary tangles in gray matter. Conversely, b-amyloid deposition was rather rare (2/16). Nonetheless, a single vole showed the contemporaneous presence of pTau in the alveus and a few Ab plaque-like deposits in the subiculum. Uninfected age-matched voles were negative for pTau and Ab.
*** These findings corroborate and extend previous evidences on the transmissibility of pTau and Ab aggregation. Furthermore, the observation of a vole with contemporaneous propagation of pTau and Ab is intriguing and deserves further studies.
P.155: Quantitative real-time analysis of disease specific tau amyloid seeding activity
Davin Henderson and Edward Hoover Prion Research Center; College of Veterinary Medicine and Biomedical Sciences; Colorado State University; Fort Collins, CO USA
A leading hypothesis for the cause of neurodegenerative diseases is the templated misfolding of cellular proteins to an amyloid state. Spongiform encephalopathies were the first diseases discovered to be caused by a misfolded amyloid-rich protein. It is now recognized that the major human neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD), and chronic traumatic encephalopathy (CTE), also are associated with amyloid formation. Moreover, AD and PD amyloids have been shown competent to transmit disease in experimental animal models, suggesting shared mechanisms with traditional prion diseases. Sensitive detection of prion disease has been advanced by in vitro amplification of low levels of disease specific amyloid seeds, e.g. serial protein misfolding amplification (sPMCA), amyloid seeding (ASA) and real-time quaking induced conversion (RT-QuIC), thereby replicating the disease process in vitro. In addition, measurement of the amyloid formation rate can estimate the level of disease-associated seed by using methods analogous to quantitative polymerase chain reaction (qPCR). In the present work, we apply these principles to show that seeding activity of in vitro generated amyloid tau and AD brain amyloid tau can be readily detected and quantitated.
P.83: Gerstmann-Str€aussler-Scheinker disease with F198S mutation: Selective propagation of PrPSc and pTau upon inoculation in bank vole
Michele Angelo Di Bari1, Romolo Nonno1, Laura Pirisinu1, Claudia D’Agostino1, Geraldina Riccardi1, Guido Di Donato1, Paolo Frassanito1, Bernardino Ghetti2, Pierluigi Gambetti3, and Umberto Agrimi1
1Department of Veterinary Public Health and Food Safety; Istituto Superiore di Sanit a; Rome, Italy;
2Indiana University-Purdue University Indianapolis; Department of Pathology and Laboratory Medicine; Indianapolis, IN USA; 3Case Western Reserve University; Cleveland, OH USA
Gerstmann-Str€aussler-Scheinker disease with F198S mutation (GSS-F198S) is characterized by the presence of PrP amyloid plaques as well as neurofibrillary tangles with abnormally-phosphorylated tau protein (pTau) in the brain. The relationship between tau protein and PrP in the pathogenesis of GSS-F198S is unknown. In a previous study, we inoculated intracerebrally 2 GSS-F198S cases in 2 lines of voles carrying either methionine (Bv109M) or isoleucine (Bv109I) at codon 109 of PrP. GSS-F198S transmitted rather efficiently to Bv109I, but not to Bv109M.
Here we investigated the presence of pTau, as assessed by immunohistochemistry with anti-pTau antibodies AT180 and PHF-1, in the same voles previously inoculated with GSSF198S. Among these voles, most Bv109I showed clinical signs after short survival times (»150 d.p.i.) and were positive for PrPSc. The remaining Bv109I and all Bv109M survived for longer times without showing prion-related pathology or detectable PrPSc. All Bv109I which were previously found PrPSc-positive,
S54 Prion 2015 Poster Abstracts
were immunonegative for pTau deposition. In contrast, pTau deposition was detected in 16/20 voles culled without clinical signs after long survival times (225–804 d.p.i.). pTau deposition was characterized by neuropil threads and coiled bodies in the alveus, and was similar in all voles analyzed.
These findings highlight that pTau from GSS-F198S can propagate in voles. Importantly, pTau propagation was independent from PrPSc, as pTau was only found in PrPSc-negative voles surviving longer than 225 d.p.i. Thus, selective transmission of PrPSc and pTau proteinopathies from GSS-F198S can be accomplished by experimental transmission in voles.
I3 Aβ Strains and Alzheimer’s Disease
Lary Walker Emory University, Atlanta, GA, USA
An essential early event in the development of Alzheimer’s disease is the misfolding and aggregation of Aβ. Enigmatically, despite the extensive deposition of human-sequence Aβ in the aging brain, nonhuman primates do not develop the full pathologic or cognitive phenotype of Alzheimer’s disease, which appears to be unique to humans. In addition, some humans with marked Aβ accumulation in the brain retain their cognitive abilities, raising the question of whether the pathogenicity of Aβ is linked to the molecular features of the misfolded protein. I will present evidence for strain-like molecular differences in aggregated Aβ between humans and nonhuman primates, and among end-stage Alzheimer patients. I will also discuss a case of Alzheimer’s disease with atypical Aβ deposition to illustrate heterogeneity in the molecular architecture of Aβ assemblies, and how this variability might influence the nature of the disease. As in the case of prion diseases, strain-like variations in the molecular architecture of Aβ could help to explain the phenotypic variability in Alzheimer’s disease, as well as the distinctively human susceptibility to the disorder.
This research was conducted in collaboration with Harry LeVine, Rebecca Rosen, Amarallys Cintron, David Lynn, Yury Chernoff, Anil Mehta and Mathias Jucker and colleagues. Supported by AG040589, RR165/OD11132, AG005119, NS077049, the CART Foundation and MetLife.
I5 Pathogenic properties of synthetically generated prions
Jiyan Ma Van Andel Research Institute, Grand Rapids, Michigan, USA
Synthetically generating prions with bacterially expressed recombinant prion protein (recPrP) strongly supports the prion hypothesis. Yet, it remains unclear whether the pathogenic properties of synthetically generated prions (rec-Prion) fully recapitulate those of naturally occurring prions. A series of analyses including intracerebral and intraperitoneal transmissions of rec-Prion in wild-type mice were performed to determine the characteristics of rec-Prion induced diseases. Results from these analyses demonstrated that the rec-Prion exhibits the same pathogenic properties with naturally occurring prions, including a titratable infectivity that can be determined by endpoint titration assays, capability of transmitting prion disease via routes other than the direct intra-cerebral inoculation, causing ultra-structural lesions that are specific to prion disease, and sharing a similar manner of visceral dissemination and neuroinvasion with naturally occurring scrapie and chronic wasting disease. These findings confirmed that the disease caused by rec-Prion in wild-type mice is bona fide prion disease or transmissible spongiform encephalopathiges, and the rec-Prion contains similar pathogenic properties as naturally occurring prions.
I6 Transmissible protein toxins in neurodegenerative disease
Jacob Ayers, David Borchelt University of Florida, Gainesville, FL, USA
Amyotrophic lateral sclerosis (ALS) is an obvious example of neurodegenerative disease that seems to spread along anatomical pathways. The spread of symptoms from the site of onset (e.g. limb) to the respiratory musculature drives the rate of disease progression. In cognitive disorders, such as Alzheimer’s disease, one can find similarly find evidence of spreading dysfunction and pathology. One mechanism to account for this spread of disease from one neural structure to another is by evoking prion-like propagation of a toxic misfolded protein from cell to cell. Recent studies in animals that model aspects of Alzheimer’s Disease, Parkinson’s Disease, and Tauopathy, have bolstered the arguments in favor of prion-like, although in most of these models the mice do not develop overt “clinical” symptoms. Recently, Jacob Ayers demonstrated that the symptoms of ALS can be transmitted from a strain of mice that expresses mutant SOD1-G93A at high levels to a second transgenic strain that expresses mutant SOD1 at low, nontoxic, levels. This model showed many prion-like features including evidence of host-adaptation (earlier and more penetrant disease upon second passage). Interestingly, homogenates from paralyzed mice expressing the G37R variant of SOD1 transmitted poorly, a finding suggestive that different SOD1 variants may exhibit strain-like properties. These “ i n d u c i b l e ” m o d e l s o f h u m a n neurodegenerative disease enable the generation of models that do not require extraordinary levels of transgene expression and provide a more precise means of initiating the disease process, advances that may translate into more predictive pre-clinical models.
P188 Transmission of amyloid pathology by peripheral administration of misfolded Aβ
Javiera Bravo-Alegria1 ,2, Rodrigo Morales2, Claudia Duran-Aniotz3, Claudio Soto2 1University of Los Andes, Santiago, Chile, 2Mitchell Center for Alzheimer’s Disease and Related Brain Disorders, Department of Neurology, University of Texas Medical School, Houston, Texas, USA, 3University of Chile, Santiago, Chile
Misfolding and aggregation of Amyloid-β (Aβ) is one of the primary events involved in the pathogenesis of Alzheimer's disease (AD). Recently, it has been proposed that Aβ aggregates can transmit and spread the pathology following a prion-like mechanism. Prions can be exogenously transmitted by many different routes of administration. In the case of Aβ, previous studies showed that intraperitoneal (i.p.) injection of seeds can accelerate cerebral amyloidosis in mouse models. However, other potential routes have not yet been studied. The goal of this work was to assess whether Aβ amyloidosis can be seeded in the brain of a transgenic mouse model of AD by peripheral administration of misfolded particles.
Young tg2576 animals (50 days old) were inoculated with a pool of brain extract coming from old Tg2576 animals (10%w/v) by different routes: i.p. (100μL), eye drops (5μL each eye, 3 times), intramuscular (i.m., 50μL), and per os (p.o., 1000μL). Animals were sacrificed at 300 days old, and brain samples were analyzed for amyloid pathology by IHC and ELISA.
The i.p., i.m., and eye drops administration of Aβ seeds significantly accelerated pathological features in tg2576. Regardless of the higher volume administered, p.o. treated animals did not show any pathological changes when compared to untreated controls. Differences in the proportion of diffuse, core and vascular deposition was observed within experimental groups. Our data show that peripheral administration of Aβ seeds could accelerate pathological changes in the brain and suggest that an orchestrated cross-talk between the brain and peripheral tissues occurs in AD.
98 | Veterinary Record | January 24, 2015
Scrapie: a particularly persistent pathogen
Resistant prions in the environment have been the sword of Damocles for scrapie control and eradication. Attempts to establish which physical and chemical agents could be applied to inactivate or moderate scrapie infectivity were initiated in the 1960s and 1970s,with the first study of this type focusing on the effect of heat treatment in reducing prion infectivity (Hunter and Millson 1964). Nowadays, most of the chemical procedures that aim to inactivate the prion protein are based on the method developed by Kimberlin and collaborators (1983). This procedure consists of treatment with 20,000 parts per million free chlorine solution, for a minimum of one hour, of all surfaces that need to be sterilised (in laboratories, lambing pens, slaughterhouses, and so on). Despite this, veterinarians and farmers may still ask a range of questions, such as ‘Is there an official procedure published somewhere?’ and ‘Is there an international organisation which recommends and defines the exact method of scrapie decontamination that must be applied?’
From a European perspective, it is difficult to find a treatment that could be applied, especially in relation to the disinfection of surfaces in lambing pens of affected flocks. A 999/2001 EU regulation on controlling spongiform encephalopathies (European Parliament and Council 2001) did not specify a particular decontamination measure to be used when an outbreak of scrapie is diagnosed. There is only a brief recommendation in Annex VII concerning the control and eradication of transmissible spongiform encephalopathies (TSE s).
Chapter B of the regulation explains the measures that must be applied if new caprine animals are to be introduced to a holding where a scrapie outbreak has previously been diagnosed. In that case, the statement indicates that caprine animals can be introduced ‘provided that a cleaning and disinfection of all animal housing on the premises has been carried out following destocking’.
Issues around cleaning and disinfection are common in prion prevention recommendations, but relevant authorities, veterinarians and farmers may have difficulties in finding the specific protocol which applies. The European Food and Safety Authority (EFSA ) published a detailed report about the efficacy of certain biocides, such as sodium hydroxide, sodium hypochlorite, guanidine and even a formulation of copper or iron metal ions in combination with hydrogen peroxide, against prions (EFSA 2009). The report was based on scientific evidence (Fichet and others 2004, Lemmer and others 2004, Gao and others 2006, Solassol and others 2006) but unfortunately the decontamination measures were not assessed under outbreak conditions.
The EFSA Panel on Biological Hazards recently published its conclusions on the scrapie situation in the EU after 10 years of monitoring and control of the disease in sheep and goats (EFSA 2014), and one of the most interesting findings was the Icelandic experience regarding the effect of disinfection in scrapie control. The Icelandic plan consisted of: culling scrapie-affected sheep or the whole flock in newly diagnosed outbreaks; deep cleaning and disinfection of stables, sheds, barns and equipment with high pressure washing followed by cleaning with 500 parts per million of hypochlorite; drying and treatment with 300 ppm of iodophor; and restocking was not permitted for at least two years. Even when all of these measures were implemented, scrapie recurred on several farms, indicating that the infectious agent survived for years in the environment, even as many as 16 years after restocking (Georgsson and others 2006).
In the rest of the countries considered in the EFSA (2014) report, recommendations for disinfection measures were not specifically defined at the government level. In the report, the only recommendation that is made for sheep is repopulation with sheep with scrapie-resistant genotypes. This reduces the risk of scrapie recurrence but it is difficult to know its effect on the infection.
Until the EFSA was established (in May 2003), scientific opinions about TSE s were provided by the Scientific Steering Committee (SSC) of the EC, whose advice regarding inactivation procedures focused on treating animal waste at high temperatures (150°C for three hours) and high pressure alkaline hydrolysis (SSC 2003). At the same time, the TSE Risk Management Subgroup of the Advisory Committee on Dangerous Pathogens (ACDP) in the UK published guidance on safe working and the prevention of TSE infection. Annex C of the ACDP report established that sodium hypochlorite was considered to be effective, but only if 20,000 ppm of available chlorine was present for at least one hour, which has practical limitations such as the release of chlorine gas, corrosion, incompatibility with formaldehyde, alcohols and acids, rapid inactivation of its active chemicals and the stability of dilutions (ACDP 2009).
In an international context, the World Organisation for Animal Health (OIE) does not recommend a specific disinfection protocol for prion agents in its Terrestrial Code or Manual. Chapter 4.13 of the Terrestrial Code, General recommendations on disinfection and disinsection (OIE 2014), focuses on foot-and-mouth disease virus, mycobacteria and Bacillus anthracis, but not on prion disinfection. Nevertheless, the last update published by the OIE on bovine spongiform encephalopathy (OIE 2012) indicates that few effective decontamination techniques are available to inactivate the agent on surfaces, and recommends the removal of all organic material and the use of sodium hydroxide, or a sodium hypochlorite solution containing 2 per cent available chlorine, for more than one hour at 20ºC.
The World Health Organization outlines guidelines for the control of TSE s, and also emphasises the importance of mechanically cleaning surfaces before disinfection with sodium hydroxide or sodium hypochlorite for one hour (WHO 1999).
Finally, the relevant agencies in both Canada and the USA suggest that the best treatments for surfaces potentially contaminated with prions are sodium hydroxide or sodium hypochlorite at 20,000 ppm. This is a 2 per cent solution, while most commercial household bleaches contain 5.25 per cent sodium hypochlorite. It is therefore recommended to dilute one part 5.25 per cent bleach with 1.5 parts water (CDC 2009, Canadian Food Inspection Agency 2013).
So what should we do about disinfection against prions? First, it is suggested that a single protocol be created by international authorities to homogenise inactivation procedures and enable their application in all scrapie-affected countries. Sodium hypochlorite with 20,000 ppm of available chlorine seems to be the procedure used in most countries, as noted in a paper summarised on p 99 of this issue of Veterinary Record (Hawkins and others 2015). But are we totally sure of its effectiveness as a preventive measure in a scrapie outbreak? Would an in-depth study of the recurrence of scrapie disease be needed?
What we can conclude is that, if we want to fight prion diseases, and specifically classical scrapie, we must focus on the accuracy of diagnosis, monitoring and surveillance; appropriate animal identification and control of movements; and, in the end, have homogeneous and suitable protocols to decontaminate and disinfect lambing barns, sheds and equipment available to veterinarians and farmers. Finally, further investigations into the resistance of prion proteins in the diversity of environmental surfaces are required.
98 | Veterinary Record | January 24, 2015
*** These results suggest that AA fibrils are relatively heat stable and that similar to prions, autoclaving at 135 °C is required to destroy the pathogenicity of AA fibrils.
*** These findings may contribute to the prevention of AA fibril transmission through food materials to different animals and especially to humans.
New studies on the heat resistance of hamster-adapted scrapie agent: Threshold survival after ashing at 600°C suggests an inorganic template of replication
The infectious agents responsible for transmissible spongiform encephalopathy (TSE) are notoriously resistant to most physical and chemical methods used for inactivating pathogens, including heat. It has long been recognized, for example, that boiling is ineffective and that higher temperatures are most efficient when combined with steam under pressure (i.e., autoclaving). As a means of decontamination, dry heat is used only at the extremely high temperatures achieved during incineration, usually in excess of 600°C. It has been assumed, without proof, that incineration totally inactivates the agents of TSE, whether of human or animal origin.
Prion Infected Meat-and-Bone Meal Is Still Infectious after Biodiesel Production
Histochemical analysis of hamster brains inoculated with the solid residue showed typical spongiform degeneration and vacuolation. Re-inoculation of these brains into a new cohort of hamsters led to onset of clinical scrapie symptoms within 75 days, suggesting that the specific infectivity of the prion protein was not changed during the biodiesel process. The biodiesel reaction cannot be considered a viable prion decontamination method for MBM, although we observed increased survival time of hamsters and reduced infectivity greater than 6 log orders in the solid MBM residue. Furthermore, results from our study compare for the first time prion detection by Western Blot versus an infectivity bioassay for analysis of biodiesel reaction products. We could show that biochemical analysis alone is insufficient for detection of prion infectivity after a biodiesel process.
Detection of protease-resistant cervid prion protein in water from a CWD-endemic area
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.
A Quantitative Assessment of the Amount of Prion Diverted to Category 1 Materials and Wastewater During Processing
Keywords:Abattoir;bovine spongiform encephalopathy;QRA;scrapie;TSE
In this article the development and parameterization of a quantitative assessment is described that estimates the amount of TSE infectivity that is present in a whole animal carcass (bovine spongiform encephalopathy [BSE] for cattle and classical/atypical scrapie for sheep and lambs) and the amounts that subsequently fall to the floor during processing at facilities that handle specified risk material (SRM). BSE in cattle was found to contain the most oral doses, with a mean of 9864 BO ID50s (310, 38840) in a whole carcass compared to a mean of 1851 OO ID50s (600, 4070) and 614 OO ID50s (155, 1509) for a sheep infected with classical and atypical scrapie, respectively. Lambs contained the least infectivity with a mean of 251 OO ID50s (83, 548) for classical scrapie and 1 OO ID50s (0.2, 2) for atypical scrapie. The highest amounts of infectivity falling to the floor and entering the drains from slaughtering a whole carcass at SRM facilities were found to be from cattle infected with BSE at rendering and large incineration facilities with 7.4 BO ID50s (0.1, 29), intermediate plants and small incinerators with a mean of 4.5 BO ID50s (0.1, 18), and collection centers, 3.6 BO ID50s (0.1, 14). The lowest amounts entering drains are from lambs infected with classical and atypical scrapie at intermediate plants and atypical scrapie at collection centers with a mean of 3 × 10−7 OO ID50s (2 × 10−8, 1 × 10−6) per carcass. The results of this model provide key inputs for the model in the companion paper published here.
*** 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.
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.
***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.
Wednesday, December 16, 2015
Objects in contact with classical scrapie sheep act as a reservoir for scrapie transmission
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.
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
Congress is all set to give NIH it's largest increase in 12 years.
Included in the bill: $350 million increase for Alzheimer’s research and an $85 million increase for the BRAIN Initiative, the project to map the human brain.
Full story at: http://ow.ly/VYKBv
great news, with not a minute to spare...
Evidence for human transmission of amyloid-β pathology and cerebral amyloid angiopathy
07 02:27 AM
Terry S. Singeltary Sr. said:
re-Evidence for human transmission of amyloid-? pathology and cerebral amyloid angiopathy
Nature 525, 247?250 (10 September 2015) doi:10.1038/nature15369 Received 26 April 2015 Accepted 14 August 2015 Published online 09 September 2015 Updated online 11 September 2015 Erratum (October, 2015)
I would kindly like to comment on the Nature Paper, the Lancet reply, and the newspaper articles.
see Singeltary full text ;
Subject: 1992 IN CONFIDENCE TRANSMISSION OF ALZHEIMER TYPE PLAQUES TO PRIMATES POSSIBILITY ON A TRANSMISSIBLE PRION REMAINS OPEN
From: . Dr J S Metiers DCMO
4 November 1992
TRANSMISSION OF ALZHEIMER TYPE PLAQUES TO PRIMATES
1. Thank you for showing me Diana Dunstan's letter. I am glad that MRC have recognised the public sensitivity of these findings and intend to report them in their proper context. 'This hopefully will avoid misunderstanding and possible distortion by the media to portray the results as having more greater significance than the findings so far justify.
2. Using a highly unusual route of transmission (intra-cerebral injection) the researchers have demonstrated the transmission of a pathological process from two cases one of severe Alzheimer's disease the other of Gerstmann-Straussler disease to marmosets. However they have not demonstrated the transmission of either clinical condition as the "animals were behaving normally when killed". As the report emphasises the unanswered question is whether the disease condition would have revealed itself if the marmosets had lived longer. They are planning further research to see if the conditions, as opposed to the partial pathological process, is transmissible.
what are the implications for public health?
3. The route 'of transmission is very specific and in the natural state of things highly unusual. However it could be argued that the results reveal a potential risk, in that brain tissue from these two patients has been shown to transmit a pathological process. Should therefore brain tissue from such cases be regarded as potentially infective? Pathologists, morticians, neuro surgeons and those assisting at neuro surgical procedures and others coming into contact with "raw" human brain tissue could in theory be at risk. However, on a priori grounds given the highly specific route of transmission in these experiments that risk must be negligible if the usual precautions for handling brain tissue are observed.
4. The other dimension to consider is the public reaction. To some extent the GSS case demonstrates little more than the transmission of BSE to a pig by intra-cerebral injection. If other prion diseases can be transmitted in this way it is little surprise that some pathological findings observed in GSS were also transmissible to a marmoset. But the transmission of features of Alzheimer's pathology is a different matter, given the much greater frequency of this disease and raises the unanswered question whether some cases are the result of a transmissible prion. The only tenable public line will be that "more research is required’’ before that hypothesis could be evaluated. The possibility on a transmissible prion remains open. In the meantime MRC needs carefully to consider the range and sequence of studies needed to follow through from the preliminary observations in these two cases. Not a particularly comfortable message, but until we know more about the causation of Alzheimer's disease the total reassurance is not practical.
J S METTERS Room 509 Richmond House Pager No: 081-884 3344 Callsign: DOH 832 llllYc!eS 2 92/11.4/1.2
>>> The only tenable public line will be that "more research is required’’ <<<
>>> possibility on a transmissible prion remains open<<<
O.K., so it’s about 23 years later, so somebody please tell me, when is "more research is required’’ enough time for evaluation ?
Self-Propagative Replication of Ab Oligomers Suggests Potential Transmissibility in Alzheimer Disease
Received July 24, 2014; Accepted September 16, 2014; Published November 3, 2014
*** Singeltary comment PLoS ***
Alzheimer’s disease and Transmissible Spongiform Encephalopathy prion disease, Iatrogenic, what if ?
Posted by flounder on 05 Nov 2014 at 21:27 GMT
Tuesday, December 1, 2015
Sorting Out Release, Uptake and Processing of Alpha-Synuclein During Prion-Like Spread of Pathology
Thursday, December 3, 2015
Transmission of Soluble and Insoluble α-Synuclein to Mice
Tuesday, September 1, 2015
Evidence for α-synuclein prions causing multiple system atrophy in humans with parkinsonism
Wednesday, September 2, 2015
Clinically Unsuspected Prion Disease Among Patients With Dementia Diagnoses in an Alzheimer’s Disease Database
Transmission of Creutzfeldt-Jakob disease to a chimpanzee by electrodes contaminated during neurosurgery.
Gibbs CJ Jr, Asher DM, Kobrine A, Amyx HL, Sulima MP, Gajdusek DC. Laboratory of Central Nervous System Studies, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.
Stereotactic multicontact electrodes used to probe the cerebral cortex of a middle aged woman with progressive dementia were previously implicated in the accidental transmission of Creutzfeldt-Jakob disease (CJD) to two younger patients. The diagnoses of CJD have been confirmed for all three cases. More than two years after their last use in humans, after three cleanings and repeated sterilisation in ethanol and formaldehyde vapour, the electrodes were implanted in the cortex of a chimpanzee. Eighteen months later the animal became ill with CJD. This finding serves to re-emphasise the potential danger posed by reuse of instruments contaminated with the agents of spongiform encephalopathies, even after scrupulous attempts to clean them.
Monday, August 17, 2015
FDA Says Endoscope Makers Failed to Report Superbug Problems OLYMPUS
I told Olympus 15 years ago about these risk factors from endoscopy equipment, disinfection, even spoke with the Doctor at Olympus, this was back in 1999. I tried to tell them that they were exposing patients to dangerous pathogens such as the CJD TSE prion, because they could not properly clean them. even presented my concern to a peer review journal GUT, that was going to publish, but then it was pulled by Professor Michael Farthing et al... see ;
Tuesday, May 26, 2015
*** Minimise transmission risk of CJD and vCJD in healthcare settings ***
Last updated 15 May 2015
Saturday, December 12, 2015
CREUTZFELDT JAKOB DISEASE CJD TSE PRION REPORT DECEMBER 14, 2015
Thursday, December 24, 2015
Revisiting the Heidenhain Variant of Creutzfeldt-Jakob Disease: Evidence for Prion Type Variability Influencing Clinical Course and Laboratory Findings
Article type: Research Article
Wednesday, January 06, 2016
CREUTZFELDT JAKOB DISEASE SURVEILLANCE IN THE U.K. 23rd ANNUAL REPORT 2014 (published 18th November 2015)
Terry S. Singeltary Sr.