Variant Creutzfeldt-Jakob Disease Research Articles

Exposure Risk of Chronic Wasting Disease in Humans.

The majority of human prion diseases are sporadic, but acquired disease can occur, as seen with variant Creutzfeldt–Jakob disease (vCJD) following consumption of bovine spongiform encephalopathy (BSE). With increasing rates of cervid chronic wasting disease (CWD), there is concern that a new form of human prion disease may arise. Currently, there is no evidence of transmission of CWD to humans, suggesting the presence of a strong species barrier; however, in vitro and in vivo studies on the zoonotic potential of CWD have yielded mixed results. The emergence of different CWD strains is also concerning, as different strains can have different abilities to cross species barriers. Given that venison consumption is common in areas where CWD rates are on the rise, increased rates of human exposure are inevitable. If CWD was to infect humans, it is unclear how it would present clinically; in vCJD, it was strain-typing of vCJD prions that proved the causal link to BSE. Therefore, the best way to screen for CWD in humans is to have thorough strain-typing of harvested cervids and human CJD cases so that we will be in a position to detect atypical strains or strain shifts within the human CJD population.

Glossary

Glossary

Improving the Predictive Value of Prion Inactivation Validation Methods to Minimize the Risks of Iatrogenic Transmission With Medical Instruments.

Prions are pathogenic infectious agents responsible for fatal, incurable neurodegenerative diseases in animals and humans. Prions are composed exclusively of an aggregated and misfolded form (PrPSc) of the cellular prion protein (PrPC). During the propagation of the disease, PrPSc recruits and misfolds PrPC into further PrPSc. In human, iatrogenic prion transmission has occurred with incompletely sterilized medical material because of the unusual resistance of prions to inactivation. Most commercial prion disinfectants validated against the historical, well-characterized laboratory strain of 263K hamster prions were recently shown to be ineffective against variant Creutzfeldt-Jakob disease human prions. These observations and previous reports support the view that any inactivation method must be validated against the prions for which they are intended to be used. Strain-specific variations in PrPSc physico-chemical properties and conformation are likely to explain the strain-specific efficacy of inactivation methods. Animal bioassays have long been used as gold standards to validate prion inactivation methods, by measuring reduction of prion infectivity. Cell-free assays such as the real-time quaking-induced conversion (RT-QuIC) assay and the protein misfolding cyclic amplification (PMCA) assay have emerged as attractive alternatives. They exploit the seeding capacities of PrPSc to exponentially amplify minute amounts of prions in biospecimens. European and certain national medicine agencies recently implemented their guidelines for prion inactivation of non-disposable medical material; they encourage or request the use of human prions and cell-free assays to improve the predictive value of the validation methods. In this review, we discuss the methodological and technical issues regarding the choice of (i) the cell-free assay, (ii) the human prion strain type, (iii) the prion-containing biological material. We also introduce a new optimized substrate for high-throughput PMCA amplification of human prions bound on steel wires, as translational model for prion-contaminated instruments.

Application of telehealth for comprehensive Creutzfeldt-Jakob disease surveillance in the United Kingdom

Creutzfeldt-Jakob disease (CJD) is a fatal human prion disease. Surveillance systems operate globally with the goals of accurate in-life case ascertainment, appropriate public health interventions to minimise secondary transmission, and monitoring trends in disease epidemiology. The UK experienced the highest incidence of variant CJD (vCJD) in the world following widespread population exposure to bovine spongiform encephalopathy (BSE). 178 cases of vCJD have been identified in the UK by the National CJD Research & Surveillance Unit (NCJDRSU), including three cases of secondary transmission via blood transfusion. The NCJDRSU performs high-fidelity surveillance, assessing all cases of suspected CJD referred to the unit. COVID-19 has caused widespread disruption to healthcare and poses a threat to services. The NCJDRSU converted to telehealth-based surveillance in March 2020. We report the results of the application of telehealth for comprehensive CJD surveillance during the first four months of the pandemic. 59 cases were assessed for suspected CJD. In 52 cases the relatives were interviewed for an informant history, by video conference or telephone call. 34 patients underwent video examination; 1 case was examined in-person. MRI images were assessed in all cases and 46 underwent CSF testing. Feedback was obtained from interviewees and the NCJDRSU team on their experiences. 50 cases were diagnosed with sporadic CJD; 5 received an alternative diagnosis, and the remaining 4 remained unresolved, with further investigations underway. Telehealth significantly reduced time taken to assessment compared to in-person assessments in 2019. Telehealth is an effective way to provide comprehensive CJD surveillance at a national level.

Human Prion Disease Surveillance in Washington State, 2006-2017

Human prion disease surveillance is critical to detect possible cases of variant Creutzfeldt-Jakob disease and other acquired forms of prion disease in the United States. Results are presented here that describe 12 years of surveillance in Washington, the only US state that has reported the presence of classic bovine spongiform encephalopathy, an animal prion disease that has been shown to transmit to humans. To describe the current prion disease surveillance system in Washington and the epidemiological and clinical results of surveillance from 2006 through 2017. This cross-sectional study reports findings from the human prion disease surveillance system in place in Washington state from January 1, 2006, through December 31, 2017. Participants included Washington residents with a clinical suspicion of human prion disease or suggestive test results from the National Prion Disease Pathology Surveillance Center or with prion disease listed as a cause of death on the death certificate. Data for this report were analyzed from June 1, 2016, to July 1, 2020. Human prion disease diagnosis. The main outcome was incidence of human prion disease cases, including identification of variant Creutzfeldt-Jakob disease. A total of 143 human prion disease cases were detected during the study period, none of which met criteria for a variant Creutzfeldt-Jakob disease diagnosis. Among 137 definite or probable cases, 123 (89.8%) occurred in persons aged 55 years or older, with a median age at death of 66 years (range, 38-84 years). Most patients were White (124 [92.5%] among 134 with reported race), and slightly over half were male (70 [51.1%]). The average annual age-adjusted prion disease incidence was 1.5 per million population per year, slightly higher than the national rate of 1.2 per million. A total of 99 cases (69.2%) were confirmed by neuropathology. Sporadic prion disease was the most common diagnosis, in 134 cases (93.7%), followed by familial prion disease in 8 cases (5.6%). One iatrogenic prion disease case (0.7%) was also reported. The findings of this cross-sectional study suggest that demographic characteristics of patients with prion disease in Washington are consistent with national findings. The slightly higher incidence rate may be due to the state's enhanced surveillance activities, including close collaboration with key partners and educational efforts targeted toward health care providers. Results indicate that surveillance will continue to be beneficial for monitoring epidemiological trends, facilitating accurate diagnoses, and detecting variant Creutzfeldt-Jakob disease or other emerging human prion disease cases.

Incidence of and Mortality Due to Human Prion Diseases in Taiwan: A Prospective 20-Year Nationwide Surveillance Study from 1998 to 2017.

IntroductionEpidemiologic studies of Creutzfeldt-Jakob disease (CJD) have been undertaken worldwide since the new variant CJD outbreak in 1996 in the United Kingdom. A nationwide report system, the Creutzfeldt-Jakob Disease Surveillance Unit (CJDSU), directed by the Centers for Disease Control of Taiwan, was established in 1997 to identify human prion diseases.MethodsFrom 1998 to 2017, 647 cases were referred to the committee for confirmation. The report to CJDSU included a structured questionnaire recording the clinical, demographic data, and potential iatrogenic exposure, and the results of the clinical and laboratory examination, including tests of blood and cerebrospinal fluid, electroencephalography, and brain magnetic resonance imaging.ResultsIn total, 356 cases (women, n=178) were ascertained to be human prion diseases, and 97.4% (n=347) were sporadic CJD, including three definite, 314 probable, and 30 possible cases; one probable variant CJD and 8 cases of the genetic form human prion diseases. The age- and gender-specific average annual incidence were also significantly higher in the second decade (0.95/1,000,000) than in the first decade (0.63/1,000,000), with an incidence rate ratio of 1.51. The incidences increased with increasing age, reaching a peak at the age of 70–79 years. The 10-year survival curve for sCJD patients showed that the 1-, 5-, and 10-year cumulative survival rate were 52%, 5%, and 1%, respectively. PRNP polymorphisms in 170 patients showed that 98.8% were M129M and 97.6% E219E.DiscussionThe significant increase in incidence after 2008 suggests the increase in the awareness of this rare disease among physicians. The longer disease duration in patients with sCJD in Taiwan than in other countries indicates that the comprehensive support of the health care system, as well as the end-of-life care culture in Taiwan, may prolong survival time in patients with such a progressive and fatal disease.

Creutzfeldt-Jacob Disease, As a Rare Cause of Dementia Should Not be Forgotten: Single-Center Experience

Introduction: Dementia, which is an important public health problem, is divided into two groups as primary and secondary dementia. Creutzfeldt–Jakob disease (CJD), which is rarely seen, is a secondary cause of dementia with a rapidly progressive course. It is a fatal neurodegenerative disorder of infectious spongiform encephalopathy that can affect humans and animals. Sporadic CJD is the most common type that can present in four forms and has typical clinical presentations of progressive cognitive impairment, myoclonus, and ataxia. We aimed to discuss the demographic, clinical, and laboratory findings of CJD cases diagnosed in the neurointensive care unit. Methods: Sixteen patients were included in this retrospective study. Age, sex, complaints on admission, duration from symptom onset to mortality, neurologic examination, brain magnetic resonance imaging (MRI), electroencephalography (EEG), and the protein 14.3.3 status of the cerebrospinal fluid (CSF) were recorded. Results: The mean age was 61.18 ± 9.1 years (range, 37–73 years), and the most common complaints on admission were cognitive impairment, disturbance in consciousness, ataxia, and gait disturbance. CSF protein 14-3-3 was positive in 100% of patients. The most common findings were periodic sharp and wave complexes on EEG, cortical or putamen and caudate nucleus hyperintensity, cortical and cerebellar atrophy on MRI. One of the patients was diagnosed as variant CJD, and the others were diagnosed as the sporadic form. Conclusions: CJD should be kept in mind in patients with myoclonus or ataxia accompanied by progressive cognitive impairment. Neuroimaging, serial EEG recordings, CSF analysis, and histopathologic examination should be performed for diagnosis.

Processing bovine intestinal mucosa to active heparin removes spiked BSE agent

Heparin is an anticoagulant sourced from animal tissues. In the 1990s, bovine-sourced heparin was withdrawn from the U.S. market due to a theoretical concern that the bovine spongiform encephalopathy (BSE) agent might contaminate crude heparin and spread to humans as variant Creutzfeldt-Jakob disease. Only porcine intestinal heparin is now marketed in the U.S. FDA has encouraged the reintroduction of bovine heparin. We applied a scaled-down laboratory model process to produce heparin as an active pharmaceutical ingredient (API) starting from bovine intestinal mucosa. The process consisted of two phases. To model the first phase, we applied enzymatic proteolysis, anionic resin separation and methanol precipitation of crude heparin. Bovine intestinal mucosa was spiked with BSE or scrapie agents. We assayed BSE- or scrapie-associated prion protein (PrPTSE) using the Real-Time Quaking-Induced Conversion (RT-QuIC) assay at each step. The process reduced PrPTSE by 4 log10 and 6 log10 from BSE-spiked and scrapie-spiked mucosa, respectively. To model the entire process, we spiked mucosa with scrapie agent and produced heparin API, reducing PrPTSE by 6.7 log10. The purification processes removed large amounts of PrPTSE from the final products. Heparin purification together with careful sourcing of raw materials should allow safely reintroducing bovine heparin in the U.S.

Experimental inoculation of CD11c+ B1 lymphocytes, CD68+ macrophages, or platelet-rich plasma from scrapie-infected sheep into susceptible sheep results in variable infectivity.

Many studies have demonstrated prion infectivity in whole blood and blood components in a variety of transmissible spongiform encephalopathies of livestock and rodents, and variant Creutzfeldt–Jakob disease in humans, as well as an association between pathogenic prion protein (PrPSc) and different immune cells (e.g. follicular dendritic cells, T and B lymphocytes, monocytes and tingible body macrophages). To further investigate the role of various blood components in prion disease transmission, we intracranially inoculated genetically susceptible VRQ/ARQ and ARQ/ARQ sheep with inocula composed of CD11c+ B1 lymphocytes, CD68 +macrophages, or platelet-rich plasma derived from clinically ill sheep infected with the US no. 13–7 scrapie agent. At the completion of the study, we found that VRQ/ARQ and ARQ/ARQ sheep inoculated with CD11c+ B1 lymphocytes and CD68+ macrophages developed scrapie with detectable levels of PrPSc in the central nervous system and lymphoreticular system, while those inoculated with platelet-rich plasma did not develop disease and did not have detectable PrPSc by immunohistochemistry or enzyme immunoassay. This study complements and expands on earlier findings that white blood cells harbour prion infectivity, and reports CD11c+ B1 lymphocytes and CD68+ macrophages as additional targets for possible preclinical detection of prion infection in blood.

Creutzfeldt-Jakob disease surveillance in Australia: update to 31 December 2019.

Nationwide surveillance of Creutzfeldt-Jakob disease and other human prion diseases is performed by the Australian National Creutzfeldt-Jakob Disease Registry (ANCJDR). National surveillance encompasses the period since 1 January 1970, with prospective surveillance occurring from 1 October 1993. Over this prospective surveillance period, considerable developments have occurred in pre-mortem diagnostics; in the delineation of new disease subtypes; and in a heightened awareness of prion diseases in healthcare settings. Surveillance practices of the ANCJDR have evolved and adapted accordingly. This report summarises the activities of the ANCJDR during 2019. Since the ANCJDR began offering diagnostic cerebrospinal fluid (CSF) 14-3-3 protein testing in Australia in September 1997, the annual number of referrals has steadily increased. In 2019, 513 domestic CSF specimens were referred for 14-3-3 protein testing and 85 persons with suspected human prion disease were formally added to the national register. As of 31 December 2019, just under half (42 cases) of the 85 suspect case notifications remain classified as 'incomplete'; 16 cases were excluded through either detailed clinical follow-up (3 cases) or neuropathological examination (13 cases); 20 cases were classified as 'definite' and seven as 'probable' prion disease. For 2019, sixty-three percent of all suspected human prion disease related deaths in Australia underwent neuropathological examination. No cases of variant or iatrogenic CJD were identified. Two possibly causal novel prion protein gene (PRNP) sequence variations were identified.

No Adaptation of the Prion Strain in a Heterozygous Case of Variant Creutzfeldt-Jakob Disease.

We investigated a clinical case of variant Creutzfeldt-Jakob Disease in a person heterozygous for methionine/valine at codon 129 of the prion protein gene and identified the same strain properties in variant Creutzfeldt-Jakob disease in methionine homozygous persons and in bovine spongiform encephalopathy. These results indicate no adaptation of the agent in a different genetic background.

Prevalence in Britain of abnormal prion protein in human appendices before and after exposure to the cattle BSE epizootic

Widespread dietary exposure of the population of Britain to bovine spongiform encephalopathy (BSE) prions in the 1980s and 1990s led to the emergence of variant Creutzfeldt-Jakob Disease (vCJD) in humans. Two previous appendectomy sample surveys (Appendix-1 and -2) estimated the prevalence of abnormal prion protein (PrP) in the British population exposed to BSE to be 237 per million and 493 per million, respectively. The Appendix-3 survey was recommended to measure the prevalence of abnormal PrP in population groups thought to have been unexposed to BSE. Immunohistochemistry for abnormal PrP was performed on 29,516 samples from appendices removed between 1962 and 1979 from persons born between 1891 through 1965, and from those born after 1996 that had been operated on from 2000 through 2014. Seven appendices were positive for abnormal PrP, of which two were from the pre-BSE-exposure era and five from the post BSE-exposure period. None of the seven positive samples were from appendices removed before 1977, or in patients born after 2000 and none came from individuals diagnosed with vCJD. There was no statistical difference in the prevalence of abnormal PrP across birth and exposure cohorts. Two interpretations are possible. Either there is a low background prevalence of abnormal PrP in human lymphoid tissues that may not progress to vCJD. Alternatively, all positive specimens are attributable to BSE exposure, a finding that would necessitate human exposure having begun in the late 1970s and continuing through the late 1990s.

No evidence of transfusion transmitted sporadic Creutzfeldt-Jakob disease: results from a bi-national cohort study.

Creutzfeldt-Jakob disease (CJD) is an uncommon, invariably fatal, neurodegenerative disorder that presents as progressive dementia with concurrent motor symptoms and myoclonia. The pathophysiology involves prion protein misfolding and spreading in a self-catalyzed manner. It has been shown to be transmissible through tissue transplants. Variant CJD (vCJD), a subtype of the disease is also transmissible through transfusion of blood products. This study aims to corroborate the scarce data that suggest that sporadic CJD (sCJD) is not transmitted via blood transfusion. A retrospective cohort study was performed, using data from the bi-national Scandinavian Donations and Transfusions (SCANDAT2) database containing data on blood donors, donations, transfusions, and transfused patients in Sweden and Denmark since 1968 and 1982, respectively. Mortality and medical data were collected from nationwide health care and population registries. Donors with subsequent CJD were identified, as well as recipients of blood products from these donors. A second analysis was performed, screening for clustering of CJD cases from donors without a CJD diagnosis. We identified 39 donors with a subsequent diagnosis of sCJD. No cases of CJD occurred among the 883 recipients of blood products from these donors. A total of 89 CJD cases were identified among recipients of transfusions. No clustering of cases from the same donor occurred. Using data from a large, bi-national database of transfused patients, we find no evidence of sCJD transmission. Our data adds to the growing body of evidence indicating that sCJD is not transfusion transmitted.

Immunotherapy against Prion Disease.

The term “prion disease” encompasses a group of neurodegenerative diseases affecting both humans and animals. Currently, there is no effective therapy and all forms of prion disease are invariably fatal. Because of (a) the outbreak of bovine spongiform encephalopathy in cattle and variant Creutzfeldt–Jakob disease in humans; (b) the heated debate about the prion hypothesis; and (c) the availability of a natural prion disease in rodents, the understanding of the pathogenic process in prion disease is much more advanced compared to that of other neurodegenerative disorders, which inspired many attempts to develop therapeutic strategies against these fatal diseases. In this review, we focus on immunotherapy against prion disease. We explain our rationale for immunotherapy as a plausible therapeutic choice, review previous trials using either active or passive immunization, and discuss potential strategies for overcoming the hurdles in developing a successful immunotherapy. We propose that immunotherapy is a plausible and practical therapeutic strategy and advocate more studies in this area to develop effective measures to control and treat these devastating disorders.

Assessment of risk of variant creutzfeldt-Jakob disease (vCJD) from use of bovine heparin.

In the late1990s, reacting to the outbreak of bovine spongiform encephalopathy (BSE) in the United Kingdom that caused a new variant of Creutzfeldt-Jakob disease (vCJD) in humans, manufacturers withdrew bovine heparin from the market in the United States. There have been growing concerns about the adequate supply and safety of porcine heparin. Since the BSE epidemic has been declining markedly, the US Food and Drug Administration reevaluates the vCJD risk via use of bovine heparin. We developed a computational model to estimate the vCJD risk to patients receiving bovine heparin injections. The model incorporated information including BSE prevalence, infectivity levels in the intestines, manufacturing batch size, yield of heparin, reduction in infectivity by manufacturing process, and the dose-response relationship. The model estimates a median risk of vCJD infection from a single intravenous dose (10 000 USP units) of heparin made from US-sourced bovine intestines to be 6.9 × 10-9 (2.5-97.fifth percentile: 1.5 × 10-9 -4.3 × 10-8 ), a risk of 1 in 145 million, and 4.6 × 10-8 (2.5-97.fifth percentile: 1.1 × 10-8 -2.6 × 10-7 ), a risk of 1 in 22 million for Canada-sourced products. The model estimates a median risk of 1.4 × 10-7 (2.5-97.fifth percentile: 2.9 × 10-8 -9.3 × 10-7 ) and 9.6 × 10-7 (2.5-97.fifth percentile: 2.1 × 10-7 -5.6 × 10-6 ) for a typical treatment for venous thromboembolism (infusion of 2-4 doses daily per week) using US-sourced and Canada-sourced bovine heparin, respectively. The model estimates the vCJD risk from use of heparin when appropriately manufactured from US or Canadian cattle is likely small. The model and conclusions should not be applied to other medicinal products manufactured using bovine-derived materials.

PMCA Applications for Prion Detection in Peripheral Tissues of Patients with Variant Creutzfeldt-Jakob Disease.

Prion diseases are neurodegenerative and invariably fatal conditions that affect humans and animals. In particular, Creutzfeldt-Jakob disease (CJD) and bovine spongiform encephalopathy (BSE) are paradigmatic forms of human and animal prion diseases, respectively. Human exposure to BSE through contaminated food caused the appearance of the new variant form of CJD (vCJD). These diseases are caused by an abnormal prion protein named PrPSc (or prion), which accumulates in the brain and leads to the onset of the disease. Their definite diagnosis can be formulated only at post-mortem after biochemical and neuropathological identification of PrPSc. Thanks to the advent of an innovative technique named protein misfolding cyclic amplification (PMCA), traces of PrPSc, undetectable with the standard diagnostic techniques, were found in peripheral tissues of patients with vCJD, even at preclinical stages. The technology is currently being used in specialized laboratories and can be exploited for helping physicians in formulating an early and definite diagnosis of vCJD using peripheral tissues. However, this assay is currently unable to detect prions associated with the sporadic CJD (sCJD) forms, which are more frequent than vCJD. This review will focus on the most recent advances and applications of PMCA in the field of vCJD and other human prion disease diagnosis.

Correlation between Bioassay and Protein Misfolding Cyclic Amplification for Variant Creutzfeldt-Jakob Disease Decontamination Studies.

To date, approximately 500 iatrogenic Creutzfeldt-Jakob disease cases have been reported worldwide, most of them resulting from cadaveric dura mater graft and from the administration of prion-contaminated human growth hormone. The unusual resistance of prions to decontamination processes, their large tissue distribution, and the uncertainty about the prevalence of variant Creutzfeldt-Jakob disease (vCJD) in the general population lead to specific recommendations regarding identification of tissue at risk and reprocessing of reusable medical devices, including the use of dedicated treatment for prion inactivation. We previously described an in vitro assay, called Surf-PMCA, which allowed us to classify prion decontamination treatments according to their efficacy on vCJD prions by monitoring residual seeding activity (RSA). Here, we used a transgenic mouse line permissive to vCJD prions to study the correlation between the RSA measured in vitro and the in vivo infectivity. Implantation in mouse brains of prion-contaminated steel wires subjected to different decontamination procedures allows us to demonstrate a good concordance between RSA measured by Surf-PMCA (in vitro) and residual infectivity (in vivo). These experiments emphasize the strength of the Surf-PMCA method as a rapid and sensitive assay for the evaluation of prion decontamination procedures and also confirm the lack of efficacy of several marketed reagents on vCJD prion decontamination.IMPORTANCE Creutzfeldt-Jakob diseases are neurodegenerative disorders for which transmission linked to medical procedures have been reported in hundreds of patients. As prion diseases, they are characterized by an unusual resistance to conventional decontamination processes. Moreover, their large tissue distribution and the ability of prions to attach to many surfaces raised the risk of transmission in health care facilities. It is therefore of major importance that decontamination procedures applied to medical devices before their reprocessing are thoroughly validated for prion inactivation. We previously described an in vitro assay, which allowed us to classify accurately prion decontamination treatments according to their efficacy on variant Creutzfeldt-Jakob disease. The significance of this study is in demonstrating the concordance between previous in vitro results and infectivity studies in transgenic mice. Furthermore, commercial reagents currently used in hospitals were tested by both protocols, and we observed that most of them were ineffective on human prions.

Preclinical Detection of Prions in Blood of Nonhuman Primates Infected with Variant Creutzfeldt-Jakob Disease.

Variant Creutzfeldt-Jakob disease (vCJD) is caused by prion infection with bovine spongiform encephalopathy and can be transmitted by blood transfusion. Protein misfolding cyclic amplification (PMCA) can detect prions in blood from vCJD patients with 100% sensitivity and specificity. To determine whether PMCA enables prion detection in blood during the preclinical stage of infection, we performed a blind study using blood samples longitudinally collected from 28 control macaques and 3 macaques peripherally infected with vCJD. Our results demonstrate that PMCA consistently detected prions in blood during the entire preclinical stage in all infected macaques, without false positives from noninfected animals, when using the optimized conditions for amplification of macaque prions. Strikingly, prions were detected as early as 2 months postinoculation (>750 days before disease onset). These findings suggest that PMCA has the potential to detect vCJD prions in blood from asymptomatic carriers during the preclinical phase of the disease.

Strain variation in treatment and prevention of human prion diseases.

Transmissible spongiform encephalopathies or prion diseases describe a number of different human disorders that differ in their clinical phenotypes, which are nonetheless united by their transmissible nature and common pathology. Clinical variation in the absence of a conventional infectious agent is believed to be encoded by different conformations of the misfolded prion protein. This misfolded protein is the target of methods designed to prevent disease transmission in a surgical setting and reduction of the misfolded seed or preventing its continued propagation have been the focus of therapeutic strategies. It is therefore possible that strain variation may influence the efficacy of prevention and treatment approaches. Historically, an understanding of prion disease transmission and pathogenesis has been focused on research tools developed using agriculturally relevant strains of prion disease. However, an increased understanding of the molecular biology of human prion disorders has highlighted differences not only between different forms of the disease affecting humans and animals but also within diseases such as Creutzfeldt-Jakob Disease (CJD), which is represented by several sporadic CJD specific conformations and an additional conformation associated with variant CJD. In this chapter we will discuss whether prion strain variation can affect the efficacy of methods used to decontaminate prions and whether strain variation in pre-clinical models of prion disease can be used to identify therapeutic strategies that have the best possible chance of success in the clinic.

Movement Disorders in Prionopathies: A Systematic Review

<strong>Background:</strong> Movement disorders are frequent features of prionopathies. However, their prevalence and onset remain poorly described. <strong>Methods:</strong> We performed a systematic review of case reports and case series of pathologically- and genetically confirmed prionopathies. Timing of symptom and movement disorder onset were documented. Continuous variables were compared between two groups using the Wilcoxon rank sum test and between multiple groups using Kruskal–Wallis test. Categorical variables were compared using Fisherfs exact test. <strong>Results:</strong> A total of 324 cases were included in this analysis. Movement disorders were a common feature at the onset of symptoms in most prionopathies. Gait ataxia was present in more than half of cases in all types of prionopathies. The prevalence of limb ataxia (20%) and myoclonus (24%) was lower in Gerstmann–Straussler–Scheinker disease compared to other prionopathies (p ≤ 0.004). Myoclonus was common but often a later feature in sporadic Creutzfeldt–Jakob disease (2 months before death). Chorea was uncommon but disproportionately prevalent in variant Creutzfeldt–Jakob disease (30% of cases; p &lt; 0.001). In genetic Creutzfeldt–Jakob disease, E200K <em>PRNP</em> carriers exhibited gait and limb ataxia more often when compared to other mutation carriers. <strong>Discussion:</strong> Movement disorders are differentially present in the course of the various prionopathies. The movement phenomenology and appearance are associated with the type of prion disease and the <em>PRNP</em> genotype and likely reflect the underlying pattern of neurodegeneration. Reliance on myoclonus as a diagnostic feature of sporadic Creutzfeldt.Jakob disease may delay its recognition given its relatively late appearance in the disease course.