Scrapie In Sheep Research Articles

Post-translational modifications in prion diseases.

More than 650 reversible and irreversible post-translational modifications (PTMs) of proteins have been listed so far. Canonical PTMs of proteins consist of the covalent addition of functional or chemical groups on target backbone amino-acids or the cleavage of the protein itself, giving rise to modified proteins with specific properties in terms of stability, solubility, cell distribution, activity, or interactions with other biomolecules. PTMs of protein contribute to cell homeostatic processes, enabling basal cell functions, allowing the cell to respond and adapt to variations of its environment, and globally maintaining the constancy of the milieu interieur (the body's inner environment) to sustain human health. Abnormal protein PTMs are, however, associated with several disease states, such as cancers, metabolic disorders, or neurodegenerative diseases. Abnormal PTMs alter the functional properties of the protein or even cause a loss of protein function. One example of dramatic PTMs concerns the cellular prion protein (PrPC), a GPI-anchored signaling molecule at the plasma membrane, whose irreversible post-translational conformational conversion (PTCC) into pathogenic prions (PrPSc) provokes neurodegeneration. PrPC PTCC into PrPSc is an additional type of PTM that affects the tridimensional structure and physiological function of PrPC and generates a protein conformer with neurotoxic properties. PrPC PTCC into PrPSc in neurons is the first step of a deleterious sequence of events at the root of a group of neurodegenerative disorders affecting both humans (Creutzfeldt-Jakob diseases for the most representative diseases) and animals (scrapie in sheep, bovine spongiform encephalopathy in cow, and chronic wasting disease in elk and deer). There are currently no therapies to block PrPC PTCC into PrPSc and stop neurodegeneration in prion diseases. Here, we review known PrPC PTMs that influence PrPC conversion into PrPSc. We summarized how PrPC PTCC into PrPSc impacts the PrPC interactome at the plasma membrane and the downstream intracellular controlled protein effectors, whose abnormal activation or trafficking caused by altered PTMs promotes neurodegeneration. We discussed these effectors as candidate drug targets for prion diseases and possibly other neurodegenerative diseases.

A Comparison of RML Prion Inactivation Efficiency by Heterogeneous and Homogeneous Photocatalysis.

Prions are proteinaceous pathogens responsible for a variety of devastating diseases in mammals, including scrapie in sheep and goats, chronic wasting disease in cervids, and Creutzfeldt-Jakob disease (CJD) in humans. They are characterized by their exceptional persistence to common inactivation procedures. This applies to all possible sources of prion contamination as prions may be present in the tissues and biological fluids of infected individuals. Hence, efficient prion inactivation procedures are still being sought to minimize the risk of intra- or inter-species transmission. In the past, photocatalytic treatment has been proven to be capable of efficiently oxidizing and inactivating prions. In the present study, the efficacy of homogeneous photo-Fenton-based photocatalysis as well as heterogeneous photocatalysis with TiO2 in reducing RML mouse scrapie infectivity was evaluated. Prion inactivation was assessed by means of a bioassay, and the results were confirmed by in vitro experiments. While the prion infectivity of the RML mouse scrapie was reduced after treatment with the photo-Fenton reagent, the heterogeneous photocatalytic treatment of the same prion strain completely eliminated prion infectivity.

Sleep disturbance in clinical and preclinical scrapie-infected sheep measured by polysomnography

Neurodegenerative diseases are characterised by neuronal loss and abnormal deposition of pathological proteins in the nervous system. Among the most common neurodegenerative diseases are Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease and transmissible spongiform encephalopathies (TSEs). Sleep and circadian rhythm disturbances are one of the most common symptoms in patients with neurodegenerative diseases. Currently, one of the main objectives in the study of TSEs is to try to establish an early diagnosis, as clinical signs do not appear until the damage to the central nervous system is very advanced, which prevents any therapeutic approach. In this paper, we provide the first description of sleep disturbance caused by classical scrapie in clinical and preclinical sheep using polysomnography compared to healthy controls. Fifteen sheep classified into three groups, clinical, preclinical and negative control, were analysed. The results show a decrease in total sleep time as the disease progresses, with significant changes between control, clinical and pre-clinical animals. The results also show an increase in sleep fragmentation in clinical animals compared to preclinical and control animals. In addition, sheep with clinical scrapie show a total loss of Rapid Eye Movement sleep (REM) and alterations in Non Rapid Eyes Movement sleep (NREM) compared to control sheep, demonstrating more shallow sleep. Although further research is needed, these results suggest that prion diseases also produce sleep disturbances in animals and that polysomnography could be a diagnostic tool of interest in clinical and preclinical cases of prion diseases.

Temporal serum neurofilament light chain concentrations in sheep inoculated with the agent of classical scrapie.

Neurofilament light chain (Nf-L) has been used to detect neuroaxonal damage in the brain caused by physical injury or disease. The purpose of this study was to determine if serum Nf-L could be used as a biomarker for pre-symptomatic detection of scrapie in sheep. Four sheep with prion protein genotype AVQQ were intranasally inoculated with the classical scrapie strain x124. Blood was collected every 4 weeks until 44 weeks post-inoculation, at which point weekly collection commenced. Serum was analyzed using single molecule array (Quanterix SR-X) to evaluate Nf-L concentrations. Scrapie was confirmed in each sheep by testing homogenized brainstem at the level of the obex with a commercially available enzyme immunoassay. Increased serum Nf-L concentrations were identified above the determined cutoff during the last tenth of the respective incubation period for each sheep. Throughout the time course study, PrPSc accumulation was not detected antemortem by immunohistochemistry in rectal tissue at any timepoint for any sheep. RT-QuIC results were inconsistently positive throughout the timepoints tested for each sheep; however, each sheep had at least one timepoint detected positive. When assessing serum Nf-L utility using receiver operator characteristic curves against different clinical parameters, such as asymptomatic and symptomatic (pruritus or neurologic signs), results showed that Nf-L was most useful at being an indicator of disease only late in disease progression when neurologic signs were present. Serum Nf-L concentrations in the cohort of sheep increased as disease progressed; however, serum Nf-L did not increase during the presymptomatic window. The levels increased substantially throughout the final 10% of the animals' scrapie incubation period when other clinical signs were present. Serum Nf-L is not a reliable biomarker for pre-clinical detection of scrapie.

Genetic characterization of the prion protein gene in camels (Camelus) with comments on the evolutionary history of prion disease in Cetartiodactyla.

Transmissible spongiform encephalopathies (TSEs) are a fatal neurogenerative disease that include Creutzfeldt-Jakob disease in humans, scrapie in sheep and goats, bovine spongiform encephalopathy (BSE), and several others as well as the recently described camel prion disease (CPD). CPD originally was documented in 3.1% of camels examined during an antemortem slaughterhouse inspection in the Ouargla region of Algeria. Of three individuals confirmed for CPD, two were sequenced for the exon 3 of the prion protein gene (PRNP) and were identical to sequences previously reported for Camelus dromedarius. Given that other TSEs, such as BSE, are known to be capable of cross-species transmission and that there is household consumption of meat and milk from Camelus, regulations to ensure camel and human health should be a One Health priority in exporting countries. Although the interspecies transmissibility of CPD currently is unknown, genotypic characterization of Camelus PRNP may be used for predictability of predisposition and potential susceptibility to CPD. Herein, eight breeds of dromedary camels from a previous genetic (mitochondrial DNA and microsatellites) and morphological study were genotyped for PRNP and compared to genotypes from CPD-positive Algerian camels. Sequence data from PRNP indicated that Ethiopian camels possessed 100% sequence identity to CPD-positive camels from Algeria. In addition, the camel PRNP genotype is unique compared to other members of the Orders Cetartiodactyla and Perissodactyla and provides an in-depth phylogenetic analysis of families within Cetartiodactyla and Perissodactyla that was used to infer the evolutionary history of the PRNP gene.

Uso da imuno-histoquímica e genotipagem do gene da proteína priônica para detecção de Scrapie em ovinos no estado de Santa Catarina, Brasil

ABSTRACT: Scrapie is a contagious disease of sheep and goats caused by prions (PrPSc). This study described an outbreak of Scrapie in sheep in the state of Santa Catarina, Brazil. An 1-year and 3-month-old sheep developed clinical signs characterized by motor incoordination of the pelvic limbs, pruritus and alopecia for three days. The 38 sheep from the flock that were over 1 year of age underwent biopsies of the third eyelid and rectal mucosa, in addition to anti-PrPsc immunohistochemistry (IHC). Blood containing EDTA was collected for PRNP gene genotyping from these sheep. Of the 38, 16 (42.10%) had immunostaining againstPrPSc. IHC-positive animals were euthanized and necropsied, as well as lambs from positive mothers. Different organs of the 19 necropsied animals were collected in 10% buffered formalin for histopathological examination and anti-PrPSc IHC of the obex. The histopathology of the obex of the female with neurological signs presented discrete multifocal vacuolization of the cytoplasm of neurons and neuropil. The anti-PrPSc IHC showed that two out of the 19 obex samples had cytoplasmic immunostaining in neurons. The genotypes reported were ARQ/ARQ in 47.36%, ARR/ARQ in 36.84%, ARQ/VRQ in 10.52% and ARQ/VRR in 5.28%. The genotyping helps to identify susceptible animals and select animals more resistant to the development of Scrapie. The anti-PrPSc IHC from lymphoid biopsies, and genotyping demonstrated the high number of positive sheep classified in susceptible group.

Disease phenotype of classical sheep scrapie is changed upon experimental passage through white-tailed deer.

Prion agents occur in strains that are encoded by the structure of the misfolded prion protein (PrPSc). Prion strains can influence disease phenotype and the potential for interspecies transmission. Little is known about the potential transmission of prions between sheep and deer. Previously, the classical US scrapie isolate (No.13-7) had a 100% attack rate in white-tailed deer after oronasal challenge. The purpose of this study was to test the susceptibility of sheep to challenge with the scrapie agent after passage through white-tailed deer (WTD scrapie). Lambs of various prion protein genotypes were oronasally challenged with WTD scrapie. Sheep were euthanized and necropsied upon development of clinical signs or at the end of the experiment (72 months post-inoculation). Enzyme immunoassay, western blot, and immunohistochemistry demonstrated PrPSc in 4 of 10 sheep with the fastest incubation occurring in VRQ/VRQ sheep, which contrasts the original No.13-7 inoculum with a faster incubation in ARQ/ARQ sheep. Shorter incubation periods in VRQ/VRQ sheep than ARQ/ARQ sheep after passage through deer was suggestive of a phenotype change, so comparisons were made in ovinized mice and with sheep with known strains of classical sheep scrapie: No. 13-7 and x-124 (that has a more rapid incubation in VRQ/VRQ sheep). After mouse bioassay, the WTD scrapie and x-124 isolates have similar incubation periods and PrPSc conformational stability that are markedly different than the original No. 13-7 inoculum. Furthermore, brain tissues of sheep with WTD scrapie and x-124 scrapie have similar patterns of immunoreactivity that are distinct from sheep with No. 13-7 scrapie. Multiple lines of evidence suggest a phenotype switch when No. 13-7 scrapie prions are passaged through deer. This represents one example of interspecies transmission of prions resulting in the emergence or selection of new strain properties that could confound disease eradication and control efforts.

Novel Prion Protein Gene Polymorphisms in Awassi Sheep in Three Regions of the Fertile Crescent.

Scrapie is a fatal, neurodegenerative disease that affects sheep and goats, and genetic susceptibility to scrapie in sheep is associated with polymorphisms in the prion protein (PRNP) gene. The aim of this study is to identify PRNP polymorphism in Awassi sheep from Türkiye, the Palestinian Authority, and Saudi Arabia. A total of 150 healthy sheep were genotyped for PRNP, using Sanger sequencing. There were seven alleles and eleven genotypes observed based on codons 136, 154, and 171 of PRNP. The ARQ allele was predominant in all populations. The most resistant allele to scrapie, ARR, was present in all three regions. The VRQ allele, associated with the highest susceptibility to scrapie, was detected only in Türkiye at a low frequency. In this study, twenty-seven amino acid substitutions were found. Eight of them (R40Q, G65E, H88L, S98T, A118P, S138T, V192F and L250I) have not been previously reported. These data indicate that sheep breeds close to the sheep domestication center have maintained high genetic diversity in the PRNP region. Our findings on PRNP will provide valuable insights for sheep breeding programs, aiding in the selection of genotypes resistant to scrapie in Türkiye, the Palestinian Authority, and Saudi Arabia.

Inter- and intra-species conversion efficacies of Norwegian prion isolates estimated by serial protein misfolding cyclic amplification

Prion diseases, including chronic wasting disease (CWD) in cervids, are fatal neurodegenerative disorders caused by the misfolding of cellular prion proteins. CWD is known to spread among captive and free-ranging deer in North America. In 2016, an outbreak of contagious CWD was detected among wild reindeer in Norway, marking the first occurrence of the disease in Europe. Additionally, new sporadic forms of CWD have been discovered in red deer in Norway and moose in Fennoscandia. We used serial protein misfolding cyclic amplification to study the ability of Norwegian prion isolates from reindeer, red deer, and moose (two isolates), as well as experimental classical scrapie from sheep, to convert a panel of 16 brain homogenates (substrates) from six different species with various prion protein genotypes. The reindeer CWD isolate successfully converted substrates from all species except goats. The red deer isolate failed to convert sheep and goat substrates but exhibited amplification in all cervid substrates. The two moose isolates demonstrated lower conversion efficacies. The wild type isolate propagated in all moose substrates and in the wild type red deer substrate, while the other isolate only converted two of the moose substrates. The experimental classical scrapie isolate was successfully propagated in substrates from all species tested. Thus, reindeer CWD and classical sheep scrapie isolates were similarly propagated in substrates from different species, suggesting the potential for spillover of these contagious diseases. Furthermore, the roe deer substrate supported conversion of three isolates suggesting that this species may be vulnerable to prion disease.

Inducing prion protein shedding as a neuroprotective and regenerative approach in pathological conditions of the brain: from theory to facts.

In the last decades, the role of the prion protein (PrP) in neurodegenerative diseases has been intensively investigated, initially in prion diseases of humans (e.g., Creutzfeldt-Jakob disease) and animals (e.g., scrapie in sheep, chronic wasting disease in deer and elk, or "mad cow disease" in cattle). Templated misfolding of physiological cellular prion protein (PrPC) into an aggregation-prone isoform (termed PrP "Scrapie" (PrPSc)), self-replication and spreading of the latter inside the brain and to peripheral tissues, and the associated formation of infectious proteopathic seeds (termed "prions") are among the essential pathogenic mechanisms underlying this group of fatal and transmissible spongiform encephalopathies. Later, key roles of the correctly folded PrPC were identified in more common human brain diseases (such as Alzheimer's disease or Parkinson's disease) associated with the misfolding and/or accumulation of other proteins (such as amyloid-β, tau or α-synuclein, respectively). PrPC has also been linked with neuroprotective and regenerative functions, for instance in hypoxic/ischemic conditions such as stroke. However, despite a mixed "bouquet" of suggested functions, our understanding of pathological and, especially, physiological roles played by PrPC in the brain and beyond is certainly incomplete. Interactions with various other proteins at the cell surface or within intracellular compartments may account for the functional diversity linked with PrPC. Moreover, conserved endogenous proteolytic processing of PrPC generates several defined PrPC fragments, possibly holding intrinsic functions in physiological and pathological conditions, thus making the "true and complete biology" of this protein more complicated to be elucidated. Here, we focus on one of those released PrPC fragments, namely shed PrP (sPrP), generated by a membrane-proximate ADAM10-mediated cleavage event at the cell surface. Similar to other soluble PrPC fragments (such as the N1 fragment representing PrP's released N-terminal tail upon the major α-cleavage event) or experimentally employed recombinant PrP, sPrP is being suggested to act neuroprotective in Alzheimer's disease and other protein misfolding diseases. Several lines of evidence on extracellular PrPC (fragments) suggest that induction of PrPC release could be a future therapeutic option in various brain disorders. Our recent identification of a substrate-specific approach to stimulate the shedding by ADAM10, based on ligands binding to cell surface PrPC, may further set the stage for research into this direction.

Efficacy of Wex-cide 128 disinfectant against multiple prion strains.

Prion diseases are transmissible, fatal neurologic diseases that include Creutzfeldt-Jakob Disease (CJD) in humans, chronic wasting disease (CWD) in cervids, bovine spongiform encephalopathy (BSE) in cattle and scrapie in sheep. Prions are extremely difficult to inactivate and established methods to reduce prion infectivity are often dangerous, caustic, expensive, or impractical. Identifying viable and safe methods for treating prion contaminated materials is important for hospitals, research facilities, biologists, hunters, and meat-processors. For three decades, some prion researchers have used a phenolic product called Environ LpH (eLpH) to inactivate prions. ELpH has been discontinued, but a similar product, Wex-cide 128, containing the similar phenolic chemicals as eLpH is now available. In the current study, we directly compared the anti-prion efficacy of eLpH and Wex-cide 128 against prions from four different species (hamster 263K, cervid CWD, mouse 22L and human CJD). Decontamination was performed on either prion infected brain homogenates or prion contaminated steel wires and mouse bioassay was used to quantify the remaining prion infectivity. Our data show that both eLpH and Wex-cide 128 removed 4.0-5.5 logs of prion infectivity from 22L, CWD and 263K prion homogenates, but only about 1.25-1.50 logs of prion infectivity from human sporadic CJD. Wex-cide 128 is a viable substitute for inactivation of most prions from most species, but the resistance of CJD to phenolic inactivation is a concern and emphasizes the fact that inactivation methods should be confirmed for each target prion strain.

Oral vaccination as a potential strategy to manage chronic wasting disease in wild cervid populations.

Prion diseases are a novel class of infectious disease based in the misfolding of the cellular prion protein (PrPC) into a pathological, self-propagating isoform (PrPSc). These fatal, untreatable neurodegenerative disorders affect a variety of species causing scrapie in sheep and goats, bovine spongiform encephalopathy (BSE) in cattle, chronic wasting disease (CWD) in cervids, and Creutzfeldt-Jacob disease (CJD) in humans. Of the animal prion diseases, CWD is currently regarded as the most significant threat due its ongoing geographical spread, environmental persistence, uptake into plants, unpredictable evolution, and emerging evidence of zoonotic potential. The extensive efforts to manage CWD have been largely ineffective, highlighting the need for new disease management tools, including vaccines. Development of an effective CWD vaccine is challenged by the unique biology of these diseases, including the necessity, and associated dangers, of overcoming immune tolerance, as well the logistical challenges of vaccinating wild animals. Despite these obstacles, there has been encouraging progress towards the identification of safe, protective antigens as well as effective strategies of formulation and delivery that would enable oral delivery to wild cervids. In this review we highlight recent strategies for antigen selection and optimization, as well as considerations of various platforms for oral delivery, that will enable researchers to accelerate the rate at which candidate CWD vaccines are developed and evaluated.

Scrapie sheep, mad cows, laughing death and slow viruses

Scrapie sheep, mad cows, laughing death and slow viruses

The Zoonotic Potential of Chronic Wasting Disease—A Review

Prion diseases are transmissible neurodegenerative disorders that affect humans and ruminant species consumed by humans. Ruminant prion diseases include bovine spongiform encephalopathy (BSE) in cattle, scrapie in sheep and goats and chronic wasting disease (CWD) in cervids. In 1996, prions causing BSE were identified as the cause of a new prion disease in humans; variant Creutzfeldt-Jakob disease (vCJD). This sparked a food safety crisis and unprecedented protective measures to reduce human exposure to livestock prions. CWD continues to spread in North America, and now affects free-ranging and/or farmed cervids in 30 US states and four Canadian provinces. The recent discovery in Europe of previously unrecognized CWD strains has further heightened concerns about CWD as a food pathogen. The escalating CWD prevalence in enzootic areas and its appearance in a new species (reindeer) and new geographical locations, increase human exposure and the risk of CWD strain adaptation to humans. No cases of human prion disease caused by CWD have been recorded, and most experimental data suggest that the zoonotic risk of CWD is very low. However, the understanding of these diseases is still incomplete (e.g., origin, transmission properties and ecology), suggesting that precautionary measures should be implemented to minimize human exposure.

A Mass Spectrometry-Based Method of Quantifying the Contribution of the Lysine Polymorphism at Position 171 in Sheep PrP.

In sheep, the transmissibility and progression of scrapie, a sheep prion (PrPSc) disease, is strongly dependent upon specific amino acid polymorphisms in the natively expressed prion protein (PrPC). Sheep expressing PrPC with lysine (K) polymorphism at position 171 (K171) are partially resistant to oronasal dosing of classical sheep scrapie. In addition, scrapie infected sheep expressing the K171 polymorphism show a longer incubation period compared to sheep homozygous (glutamine (Q)) at position 171. Quantitating the amount of the K171 polymorphism in a sheep scrapie sample can provide important information on the composition of PrPSc. A tryptic peptide, 159R.YPNQVYYRPVDK.Y172, derived from the digestion of 171K recombinant PrP, was identified as an analyte peptide suitable for a multiple reaction monitoring-based analysis. This method, using 15N-labeled analogs and another internal peptide from the proteinase K-resistant core, permits the simultaneous quantitation of the total amount of PrP and the proportion of K171 polymorphism in the sample. Background molecules with similar retention times and transitions were present in samples from scrapie-infected sheep. Proteinase K digestion followed by ultracentrifugation-based isolation or phosphotungstic acid-based isolation were employed to minimize the contribution of those background molecules, making this approach suitable for quantitating the amount of the K171 polymorphism in heterozygous scrapie infected sheep.

Characterization of Classical Sheep Scrapie in White-tailed Deer after Experimental Oronasal Exposure.

Classic scrapie is a prion disease of sheep and goats that is associated with accumulation of abnormal prion protein (PrPSc) in the central nervous and lymphoid tissues. Chronic wasting disease (CWD) is the prion disease of cervids. This study was conducted to determine the susceptibility of white-tailed deer (WTD) to the classic scrapie agent. We inoculated WTD (n = 5) by means of a concurrent oral/intranasal exposure with the classic scrapie agent from sheep or oronasally with the classic scrapie agent from goats (n = 6). All deer exposed to the agent of classic scrapie from sheep accumulated PrPSc. PrPSc was detected in lymphoid tissues at preclinical time points, and necropsies in deer 28 months after inoculation showed clinical signs, spongiform lesions, and widespread PrPSc in neural and lymphoid tissues. Western blots on samples from the brainstem, cerebellum, and lymph nodes of scrapie-infected WTD have a molecular profile similar to CWD and distinct from samples from the cerebral cortex, retina, or the original classic scrapie inoculum. There was no evidence of PrPSc in any of the WTD inoculated with classic scrapie prions from goats. WTD are susceptible to the agent of classic scrapie from sheep, and differentiation from CWD may be difficult.

Prion strains: shining new light on old concepts.

Prion diseases are a group of inevitably fatal neurodegenerative disorders affecting numerous mammalian species, including humans. The existence of heritable phenotypes of disease in the natural host suggested that prions exist as distinct strains. Transmission of sheep scrapie to rodent models accelerated prion research, resulting in the isolation and characterization of numerous strains with distinct characteristics. These strains are grouped into categories based on the incubation period of disease in different strains of mice and also by how stable the strain properties were upon serial passage. These classical studies defined the host and agent parameters that affected strain properties, and, prior to the advent of the prion hypothesis, strain properties were hypothesized to be the result of mutations in a nucleic acid genome of a conventional pathogen. The development of the prion hypothesis challenged the paradigm of infectious agents, and, initially, the existence of strains was difficult to reconcile with a protein-only agent. In the decades since, much evidence has revealed how a protein-only infectious agent can perform complex biological functions. The prevailing hypothesis is that strain-specific conformations of PrPSc encode prion strain diversity. This hypothesis can provide a mechanism to explain the observed strain-specific differences in incubation period of disease, biochemical properties of PrPSc, tissue tropism, and subcellular patterns of pathology. This hypothesis also explains how prion strains mutate, evolve, and adapt to new species. These concepts are applicable to prion-like diseases such as Parkinson's and Alzheimer's disease, where evidence of strain diversity is beginning to emerge.

Innate Immune Tolerance in Microglia Does Not Impact on Central Nervous System Prion Disease.

Prion diseases such as Creutzfeldt-Jakob disease in humans, bovine spongiform encephalopathy in cattle, and scrapie in sheep, are infectious and chronic neurodegenerative diseases to which there are no cures. Infection with prions in the central nervous system (CNS) ultimately causes extensive neurodegeneration, and this is accompanied by prominent microglial and astrocytic activation in affected regions. The microglia are the CNS macrophages and help maintain neuronal homeostasis, clear dead or dying cells and provide defense against pathogens. The microglia also provide neuroprotection during CNS prion disease, but their pro-inflammatory activation may exacerbate the development of the neuropathology. Innate immune tolerance induced by consecutive systemic bacterial lipopolysaccharide (LPS) treatment can induce long-term epigenetic changes in the microglia in the brain that several months later can dampen their responsiveness to subsequent LPS treatment and impede the development of neuritic damage in a transgenic mouse model of Alzheimer’s disease-like pathology. We therefore reasoned that innate immune tolerance in microglia might similarly impede the subsequent development of CNS prion disease. To test this hypothesis groups of mice were first infected with prions by intracerebral injection, and 35 days later given four consecutive systemic injections with LPS to induce innate immune tolerance. Our data show that consecutive systemic LPS treatment did not affect the subsequent development of CNS prion disease. Our data suggests innate immune tolerance in microglia does not influence the subsequent onset of prion disease-induced neuropathology in mice, despite previously published evidence of this effect in an Alzheimer’s disease mouse model.

Strain Typing of Classical Scrapie and Bovine Spongiform Encephalopathy (BSE) by Using Ovine PrP (ARQ/ARQ) Overexpressing Transgenic Mice.

Transmissible spongiform encephalopathies (TSE), caused by abnormal prion protein (PrPSc), affect many species. The most classical scrapie isolates harbor mixtures of strains in different proportions. While the characterization of isolates has evolved from using wild-type mice to transgenic mice, no standardization is established yet. Here, we investigated the incubation period, lesion profile and PrPSc profile induced by well-defined sheep scrapie isolates, bovine spongiform encephalopathy (BSE) and ovine BSE after intracerebral inoculation into two lines of ovine PrP (both ARQ/ARQ) overexpressing transgenic mice (Tgshp IX and Tgshp XI). All isolates were transmitted to both mouse models with an attack rate of almost 100%, but genotype-dependent differences became obvious between the ARQ and VRQ isolates. Surprisingly, BSE induced a much longer incubation period in Tgshp XI compared to Tgshp IX. In contrast to the histopathological lesion profiles, the immunohistochemical PrPSc profiles revealed discriminating patterns in certain brain regions in both models with clear differentiation of both BSE isolates from scrapie. These data provide the basis for the use of Tgshp IX and XI mice in the characterization of TSE isolates. Furthermore, the results enable a deeper appreciation of TSE strain diversity using ovine PrP overexpressing transgenic mice as a biological prion strain typing approach.

Scrapie in Eastern Libya: Case Report in Sheep

Here we report neuropathological features of scrapie cases detected between 2018 and 2022.
 Fourteen cases of sheep older than 2 years from several areas in Libya with neurological clinical signs resembling those with Scrapie were submitted to the Veterinary Teaching Hospital at Omar Al-Mukhtar University / Al-Beida. Postmortem examinations were performed on all animals after euthanasia. Samples from different organs were submitted for histopathological examination. Routine Hematoxylin and Eosin stain (HE) was used.
 Nine cases showed neuronal vacuolation that is characteristic of Scrapie in sheep. Two cases were suspected for Scrapie and need more advanced methods such as Immunohistochemistry (IHC) to confirm the diagnosis. The other three cases were diagnosed with Rabies, Listeria, and Echinococcus granulosus.