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

BACKGROUND: 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. METHODS: 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). RESULTS: 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. CONCLUSIONS: WTD are susceptible to the agent of classic scrapie from sheep, and differentiation from CWD may be difficult.

Experimental Transmission of the Chronic Wasting Disease Agent to Swine after Oral or Intracranial Inoculation.

Chronic wasting disease (CWD) is a naturally occurring, fatal neurodegenerative disease of cervids. The potential for swine to serve as hosts for the agent of CWD is unknown. The purpose of this study was to investigate the susceptibility of swine to the CWD agent following experimental oral or intracranial inoculation. Crossbred piglets were assigned to three groups, intracranially inoculated (n = 20), orally inoculated (n = 19), and noninoculated (n = 9). At approximately the age at which commercial pigs reach market weight, half of the pigs in each group were culled ("market weight" groups). The remaining pigs ("aged" groups) were allowed to incubate for up to 73 months postinoculation (mpi). Tissues collected at necropsy were examined for disease-associated prion protein (PrPSc) by Western blotting (WB), antigen capture enzyme immunoassay (EIA), immunohistochemistry (IHC), and in vitro real-time quaking-induced conversion (RT-QuIC). Brain samples from selected pigs were also bioassayed in mice expressing porcine prion protein. Four intracranially inoculated aged pigs and one orally inoculated aged pig were positive by EIA, IHC, and/or WB. By RT-QuIC, PrPSc was detected in lymphoid and/or brain tissue from one or more pigs in each inoculated group. The bioassay was positive in four out of five pigs assayed. This study demonstrates that pigs can support low-level amplification of CWD prions, although the species barrier to CWD infection is relatively high. However, detection of infectivity in orally inoculated pigs with a mouse bioassay raises the possibility that naturally exposed pigs could act as a reservoir of CWD infectivity.IMPORTANCE We challenged domestic swine with the chronic wasting disease agent by inoculation directly into the brain (intracranially) or by oral gavage (orally). Disease-associated prion protein (PrPSc) was detected in brain and lymphoid tissues from intracranially and orally inoculated pigs as early as 8 months of age (6 months postinoculation). Only one pig developed clinical neurologic signs suggestive of prion disease. The amount of PrPSc in the brains and lymphoid tissues of positive pigs was small, especially in orally inoculated pigs. Regardless, positive results obtained with orally inoculated pigs suggest that it may be possible for swine to serve as a reservoir for prion disease under natural conditions.

Horizontal Transmission of Chronic Wasting Disease in Reindeer.

We challenged reindeer by the intracranial route with the agent of chronic wasting disease sourced from white-tailed deer, mule deer, or elk and tested for horizontal transmission to naive reindeer. Reindeer were susceptible to chronic wasting disease regardless of source species. Horizontal transmission occurred through direct contact or indirectly through the environment.

Chronic wasting disease in bank voles: characterisation of the shortest incubation time model for prion diseases.

In order to assess the susceptibility of bank voles to chronic wasting disease (CWD), we inoculated voles carrying isoleucine or methionine at codon 109 (Bv109I and Bv109M, respectively) with CWD isolates from elk, mule deer and white-tailed deer. Efficient transmission rate (100%) was observed with mean survival times ranging from 156 to 281 days post inoculation. Subsequent passages in Bv109I allowed us to isolate from all CWD sources the same vole-adapted CWD strain (Bv(109I)CWD), typified by unprecedented short incubation times of 25-28 days and survival times of ∼35 days. Neuropathological and molecular characterisation of Bv(109I)CWD showed that the classical features of mammalian prion diseases were all recapitulated in less than one month after intracerebral inoculation. Bv(109I)CWD was characterised by a mild and discrete distribution of spongiosis and relatively low levels of protease-resistant PrP(Sc) (PrP(res)) in the same brain regions. Despite the low PrP(res) levels and the short time lapse available for its accumulation, end-point titration revealed that brains from terminally-ill voles contained up to 10(8,4) i.c. ID50 infectious units per gram. Bv(109I)CWD was efficiently replicated by protein misfolding cyclic amplification (PMCA) and the infectivity faithfully generated in vitro, as demonstrated by the preservation of the peculiar Bv(109I)CWD strain features on re-isolation in Bv109I. Overall, we provide evidence that the same CWD strain was isolated in Bv109I from the three-cervid species. Bv(109I)CWD showed unique characteristics of "virulence", low PrP(res) accumulation and high infectivity, thus providing exceptional opportunities to improve basic knowledge of the relationship between PrP(Sc), neurodegeneration and infectivity.

Who's your expert? Use of an expert opinion survey to inform development of American Psychiatric Association practice guidelines.

OBJECTIVE: For many clinical questions in psychiatry, high-quality evidence is lacking. Credible practice guidelines for such questions depend on transparent, reproducible, and valid methods for assessing expert opinion. The objective of this study was to develop and demonstrate the feasibility of a method for assessing expert opinion to aid in the development of practice guidelines by the American Psychiatric Association (APA). METHODS: A "snowball" process initially soliciting nominees from three sets of professional leaders was used to identify experts on a guideline topic (psychiatric evaluation). In a Web-based survey, the experts were asked to rate their level of agreement that specific assessments improve specific outcomes when they are included in an initial psychiatric evaluation. The experts were also asked about their own practice patterns with respect to the doing of the assessments. The main outcome measures are the following: number of nominated experts, number of experts who participated in the survey, and number and nature of quantitative and qualitative responses. RESULTS: The snowball process identified 1,738 experts, 784 (45 %) of whom participated in the opinion survey. Participants generally, but not always, agreed or strongly agreed that the assessments asked about would improve specified outcomes. Participants wrote 716 comments explaining why they might not typically include some assessments in an initial evaluation and 1,590 comments concerning other aspects of the topics under consideration. CONCLUSIONS: The snowball process based on initial solicitation of Psychiatry's leaders produced a large expert panel. The Web-based survey systematically assessed the opinions of these experts on the utility of specific psychiatric assessments, providing useful information to substantiate opinion-based practice guidelines on how to conduct a psychiatric evaluation. The considerable engagement of respondents shows promise for using this methodology in developing future APA practice guidelines.

Distinguishing ASH clinical practice guidelines from other forms of ASH clinical advice.

ABSTRACT: The American Society of Hematology (ASH) develops a variety of resources that provide guidance to clinicians on the diagnosis and management of blood diseases. These resources include clinical practice guidelines (CPGs) and other forms of clinical advice. Although both ASH CPGs and other forms of clinical advice provide recommendations, they differ with respect to the methods underpinning their development, the principal type of recommendations they offer, their transparency and concordance with published evidence, and the time and resources required for their development. It is crucial that end users be aware of the differences between CPGs and other forms of clinical advice and that producers and publishers of these resources use clear and unambiguous terminology to facilitate their distinction. The objective of this article is to highlight the similarities and differences between ASH CPGs and other forms of ASH clinical advice and discuss the implications of these differences for end users.

White-tailed deer are susceptible to the agent of sheep scrapie by intracerebral inoculation.

Interspecies transmission studies afford the opportunity to better understand the potential host range and origins of prion diseases. The purpose of this experiment was to determine susceptibility of white-tailed deer to the agent of scrapie after intracerebral inoculation and to compare clinical signs and lesions to those reported for chronic wasting disease (CWD). Deer (n = 5) were inoculated with 1 mL of a 10% (wt/vol) brain homogenate derived from a sheep clinically affected with scrapie. A non-inoculated deer was maintained as a negative control. Deer were observed daily for clinical signs of disease and euthanized and necropsied when unequivocal signs of scrapie were noted. One animal died 7 months post inoculation (pi) due to intercurrent disease. Examinations of brain tissue for the presence of the disease-associated abnormal prion protein (PrP(Sc)) by western blot (WB) and immunohistochemistry (IHC) were negative whereas IHC of lymphoid tissues was positive. Deer necropsied at 15-22 months pi were positive for scrapie by IHC and WB. Deer necropsied after 20 months pi had clinical signs of depression and progressive weight loss. Tissues with PrP(Sc) immunoreactivity included brain (at levels of cerebrum, hippocampus, colliculus, cerebellum, and brainstem), trigeminal ganglion, neurohypophysis, retina, spinal cord, and various lymphoid tissues including tonsil, retropharyngeal and mesenteric lymph nodes, Peyer's patches, and spleen. This work demonstrates for the first time that white-tailed deer are susceptible to sheep scrapie by intracerebral inoculation. To further test the susceptibility of white-tailed deer to scrapie these experiments will be repeated with a more natural route of inoculation.

Methodology for adaptation of the ASH Guidelines for Management of Venous Thromboembolism for the Latin American context.

BACKGROUND: From 2017 to 2020, the American Society of Hematology (ASH) collaborated with 12 hematology societies in Latin America to adapt the ASH guidelines on venous thromboembolism (VTE). OBJECTIVE: To describe the methods used to adapt the ASH guidelines on venous thromboembolism. METHODS: Each society nominated 1 individual to serve on the guideline panel. The work of the panel was facilitated by the 2 methodologists. The methods team selected 4 of the original VTE guidelines for a first round. To select the most relevant questions, a 2-step prioritization process was conducted through an on-line survey and then through in-person discussion. During an in-person meeting in Rio de Janeiro, Brazil, from 23 April through 26 April 2018, the panel developed recommendations using the ADOLOPMENT approach. Evidence about health effects from the original guidelines was reused, but important data about resource use, accessibility, feasibility, and impact in health equity were added. RESULTS: In the guideline accompanying this paper, Latin American panelists selected 17 questions from an original pool of 49. Of the 17 questions addressed, substantial changes were introduced for 5 recommendations, and remarks were added or modified for 12 recommendations. CONCLUSIONS: By using the evidence from an international guideline, a significant amount of work and time were saved; by adding regional evidence, the final recommendations were tailored to the Latin American context. This experience offers an alternative to develop guidelines relevant to local contexts through a global collaboration.

How to write a guideline: a proposal for a manuscript template that supports the creation of trustworthy guidelines.

Trustworthy health guidelines should provide recommendations, document the development process, and highlight implementation information. Our objective was to develop a guideline manuscript template to help authors write a complete and useful report. The McMaster Grading of Recommendations Assessment, Development and Evaluation Centre collaborated with the American Society of Hematology (ASH) to develop guidelines for the management of venous thromboembolism. A template for reporting the guidelines was developed based on prior approaches and refined using input from other key stakeholders. The proposed guideline manuscript template includes: (1) title for guideline identification, (2) abstract, including a summary of key recommendations, (3) overview of all recommendations (executive summary), and (4) the main text, providing sufficient detail about the entire process, including objectives, background, and methodological decisions from panel selection and conflict-of-interest management to criteria for updating, as well as supporting information, such as links to online (interactive) tables. The template further allows for tailoring to the specific topic, using examples. Initial experience with the ASH guideline manuscript template was positive, and challenges included drafting descriptions of recommendations involving multiple management pathways, tailoring the template for a specific guideline, and choosing key recommendations to highlight. Feedback from a larger group of guideline authors and users will be needed to evaluate its usefulness and refine. The proposed guideline manuscript template is the first detailed template for transparent and complete reporting of guidelines. Consistent application of the template may simplify the preparation of an evidence-based guideline manuscript and facilitate its use.

Fluorescence spectroscopy of the retina for diagnosis of transmissible spongiform encephalopathies.

The feasibility of exploiting fluorescence spectra of the eye for diagnosis of transmissible spongiform encephalopathies (TSEs) was examined. Retinas from scrapie-positive sheep were compared with scrapie-negative sheep using fluorescence spectroscopy, and distinct differences in the fluorescence intensity and spectroscopic signatures were observed. The characteristic fluorescent signatures are thought to be the result of an accumulation of lipofuscin in the retina. It appears that the eye, in particular the retina, is a useful tissue for noninvasive examination of some neurological pathologies such as scrapie. The development of procedures based on examinations of the eye that permit the detection of neurological disorders in animals holds great promise.

Detection of PrP(Sc) in formalin-fixed, paraffin-embedded tissue by Western blot differentiates classical scrapie, Nor98 scrapie, and bovine spongiform encephalopathy.

Transmissible, spongiform encephalopathies including bovine spongiform encephalopathy (BSE) and scrapie are fatal neurodegenerative disorders associated with the presence of an infectious abnormal isoform of normal mammalian proteins called prions. Identification of the prion protein associated with scrapie (PrP(Sc)) in the central nervous system is typically based upon immunoassays including immunohistochemistry (IHC) using formalin-fixed tissues or Western blot (WB) assays using fresh and/or frozen, non-formalin-fixed tissues. Each assay can discriminate between BSE, classical scrapie, and a previously reported strain of scrapie recently identified in the United States named Nor98 scrapie. Different tissue samples are required from the same animal to run these 2 different immunoassays. This may result in inconsistent test results for the same animal. Sampling problems such as collecting insufficient volumes of fresh tissue or less than optimal anatomic location of brainstem for IHC can affect the ability of the test procedures to offer definitive and discriminatory results. Recently, a WB method using formalin-fixed, paraffin-embedded (FFPE) tissue to identify PrP(Sc) was developed that successfully identified PrP(Sc) in sheep affected by classical scrapie. In the current study, the use of this technique to produce discriminatory results identifying classical BSE in bovine tissue and both classical and Nor98 scrapie in ovine tissue using paraffin-embedded brain samples is described. Protein-banding patterns from WB using FFPE tissue were similar to protein-banding patterns produced by WB assays utilizing fresh tissues from the same animals, and results correlated well with the IHC PrP(Sc)-positive staining present in the cerebellum and obex regions of brain samples from these animals.

A user guide to the American Society of Hematology clinical practice guidelines.

Since November 2018, Blood Advances has published American Society of Hematology (ASH) clinical practice guidelines on venous thromboembolism, immune thrombocytopenia, and sickle cell disease. More ASH guidelines on these and other topics are forthcoming. These guidelines have been developed using consistent processes, methods, terminology, and presentation formats. In this article, we describe how patients, clinicians, policymakers, researchers, and others may use ASH guidelines and the many related derivates by describing how to interpret information and how to apply it to clinical decision-making. Also, by exploring how these documents are developed, we aim to clarify their limitations and possible inappropriate usage.

Methodology for the American Society of Hematology VTE guidelines: current best practice, innovations, and experiences.

BACKGROUND: Methods for the development of clinical guidelines have advanced dramatically over the past 2 decades to strive for trustworthiness, transparency, user-friendliness, and rigor. The American Society of Hematology (ASH) guidelines on venous thromboembolism (VTE) have followed these advances, together with application of methodological innovations. OBJECTIVE: In this article, we describe methods and methodological innovations as a model to inform future guideline enterprises by ASH and others to achieve guideline standards. Methodological innovations introduced in the development of the guidelines aim to address current challenges in guideline development. METHODS: We followed ASH policy for guideline development, which is based on the Guideline International Network (GIN)-McMaster Guideline Development Checklist and current best practices. Central coordination, specialist working groups, and expert panels were established for the development of 10 VTE guidelines. Methodological guidance resources were developed to guide the process across guidelines panels. A methods advisory group guided the development and implementation of methodological innovations to address emerging challenges and needs. RESULTS: The complete set of VTE guidelines will include >250 recommendations. Methodological innovations include the use of health-outcome descriptors, online voting with guideline development software, modeling of pathways for diagnostic questions, application of expert evidence, and a template manuscript for publication of ASH guidelines. These methods advance guideline development standards and have already informed other ASH guideline projects. CONCLUSIONS: The development of the ASH VTE guidelines followed rigorous methods and introduced methodological innovations during guideline development, striving for the highest possible level of trustworthiness, transparency, user-friendliness, and rigor.

Experimental oral transmission of United States origin scrapie to neonatal sheep.

Scrapie, a transmissible spongiform encephalopathy (TSE), is a naturally occurring fatal neurodegenerative disease of sheep and goats. The current study documents incubation periods, pathologic findings, and distribution of abnormal prion proteins (PrP(Sc)) by immunohistochemistry and Western blot in tissues of genetically susceptible and resistant neonatal lambs inoculated with pooled brain homogenates from 13 U.S. origin scrapie-affected ewes. Nine Suffolk lambs with genotypes AA/RR/QQ (n = 5) and AA/RR/QR (n = 4) at codons 136, 154, and 171, respectively) were orally inoculated, within 12 hr of birth, with 1 ml of a 10% (w/v) brain homogenate prepared from scrapie-affected sheep brains. Inoculated animals were euthanized when advanced clinical signs of scrapie were observed. All QQ sheep developed clinical signs of scrapie, with a mean survival time of 24 months. Spongiform lesions in the brains and PrP(Sc) deposits in the central nervous system and lymphoid tissues were present in these sheep. None of the QR sheep succumbed to the disease. A previous study that used a larger volume (30 ml of 10% brain suspension) of the same inoculum in 4-month-old Suffolk lambs of susceptible genotype documented longer survival periods (average 32 months), and only 5 of 9 inoculated sheep developed scrapie. Findings of this study suggest that orally exposed neonatal lambs of a susceptible (QQ) genotype exhibit a higher attack rate and shorter incubation period than older (4-month-old) lambs exposed to a larger dose (30x) of the same inoculum.

Strain-specific virulence of Bordetella hinzii in poultry.

Bordetella hinzii is commonly acquired from the respiratory tract of diseased poultry but is generally regarded as nonpathogenic in avian hosts because attempts to demonstrate disease following experimental infection of chickens and turkeys have failed. Recently, with the availability of highly specific DNA-based methods for identification of this agent, it was recognized that some isolates used in previous studies were misidentified at the time of their acquisition as Bordetella avium, B. avium-like, or Alcaligenes faecalis type II, including a subset reported to cause disease in turkey poults. In this study six strains of B. hinzii, genetically distinct and representing all known host species, were evaluated for their ability to colonize and cause disease in turkeys following intranasal administration. Although five strains were able to colonize the tracheas of turkey poults, only a subset induced clinical signs of disease, B. hinzii-specific antibodies, or tracheal lesions. The sixth isolate was undetectable in tracheal swabs obtained 1 or 2 weeks postinfection. Birds of this group displayed no clinical signs and minimal tracheal lesions. All remained B. hinzii seronegative. Three of the six strains, differing in their capacity to colonize and/or cause disease in turkeys, were used to infect chicks intranasally. Only one was able to colonize the trachea but did not induce tracheal lesions. No clinical signs of disease were observed in any chick. These results demonstrate that some strains of B. hinzii are virulent in turkey poults and may asymptomatically colonize chicks, and suggest this agent may be of concern to poultry producers.

Western blot detection of PrP Sc in archived paraffin-embedded brainstem from scrapie-affected sheep.

Scrapie is a naturally occurring fatal neurodegenerative disease of adult sheep and goats, one of a group of mammalian diseases known as transmissible spongiform encephalopathies (TSE) or prion diseases. Immunoassays that identify disease-associated prion protein (PrP Sc) are integral to the diagnosis of scrapie and other prion diseases. Results obtained by either immunohistochemistry (IHC) or Western blot (WB) assay are generally adequate for the definitive diagnosis. Approved or accepted methods for WB diagnosis of TSEs requires the use of fresh or frozen nonfixed tissue samples, whereas formalin-fixed, paraffin-embedded tissue is required for the localization of PrP Sc by IHC. Because disparate processing methods are used for these accepted diagnostic techniques, separate tissue samples are collected from the same animal. Occasions arise in which there is either insufficient quantity of tissue available to complete analysis by both techniques or initial tissue processing is incompatible with one of the assays. Also, results between the assays may differ because of the vagaries of sampling, especially in case material that contains moderate-to-low levels of PrP Sc. The present article describes a method to conduct a WB assay from the same paraffin-embedded brainstem sample used for the IHC diagnosis of experimentally induced sheep scrapie.

Experimental transmission of scrapie agent to susceptible sheep by intralingual or intracerebral inoculation.

Scrapie, a transmissible spongiform encephalopathy (TSE), is a naturally occurring fatal neurodegenerative disease of sheep and goats. This study documents survival periods, pathological findings, and the presence of abnormal prion protein (PrP(Sc)) in genetically susceptible sheep inoculated with scrapie agent. Suffolk lambs (AA/RR/QQ at codons 136, 154, and 171, respectively) aged 4 mo were injected by the intralingual (IL) or intracerebral (IC) route with an inoculum prepared from a pool of scrapie-affected US sheep brains. The animals were euthanized when advanced clinical signs of scrapie were observed. Spongiform lesions in the brain and PrPsc deposits in the central nervous system (CNS) and lymphoid tissues were detected by immunohistochemical and Western blot (WB) testing in all the sheep with clinical prion disease. The mean survival period was 18.3 mo for the sheep inoculated by the IL route and 17.6 mo for those inoculated by the IC route. Since the IC method is occasionally associated with anesthesia-induced complications, intracranial hematoma, and CNS infections, and the IL method is very efficient, it may be more humane to use the latter. However, before this method can be recommended for inoculation of TSE agents, research needs to show that other TSE agents can also transmit disease via the tongue.

Wasting and neurologic signs in a white-tailed deer (Odocoileus virginianus) not associated with abnormal prion protein.

A captive adult male white-tailed deer (Odocoileus virginianus) with wasting and neurologic signs similar to chronic wasting disease (CWD) was evaluated by histopathology, histochemistry, and immunohistochemistry (IHC) for disease-associated prion protein (PrP(d)). On histologic examination, the brainstem had areas of vacuolation in neuropil and extensive multifocal mineralization of blood vessels with occasional occlusion of the lumen. Some of the clinical and pathologic features of this case were similar to the CWD of white-tailed deer. However, the tissues were negative for PrP(d) by IHC. Because the lesions were more prominent in the obex region of the brainstem, it is speculated that this would have resulted in clinical signs similar to CWD in white-tailed deer. To our knowledge, neither cerebrovascular mineralization nor clinicopathologic changes resembling CWD have previously been described in white-tailed deer without the presence of PrP(d). Such a case should be considered in a differential diagnosis of CWD of white-tailed deer.

Detection of the disease-associated isoform of the prion protein in formalin-fixed tissues by Western blot.

Clinical signs of prion disease are not specific and include a variety of differential diagnoses. Serological tests and nucleic acid-based detection methods are not applicable to prion-disease-agent detection because of the unusual nature of the infectious agent. Prion-disease diagnosis is primarily conducted by means of immunodetection of the infectious agent, typically by at least 2 distinct procedures with immunohistochemistry and Western blot being the most informative. These approaches differ in the need for formalin-fixed and frozen or fresh tissue respectively. This work describes a method for the detection of the disease-associated isoform of the prion protein by Western blot using formalin-fixed tissues. The approach requires only minimal modification of existing Western-blot procedures and could readily be incorporated into existing detection schemes for confirmatory purposes when fresh or frozen tissues are unavailable.