Enhanced Creutzfeldt-Jakob disease surveillance in the older population: Assessment of a protocol for screening brain tissue donations for prion disease.

Human prion diseases, including Creutzfeldt-Jakob disease (CJD), occur in sporadic, genetic, and acquired forms. Variant Creutzfeldt-Jakob disease (vCJD) first reported in 1996 in the United Kingdom (UK), resulted from contamination of food with bovine spongiform encephalopathy. There is a concern that UK national surveillance mechanisms might miss some CJD cases (including vCJD), particularly in the older population where other neurodegenerative disorders are more prevalent. We developed a highly sensitive protocol for analysing autopsy brain tissue for the misfolded prion protein (PrPSc ) associated with prion disease, which could be used to screen for prion disease in the elderly. Brain tissue samples from 331 donors to the Edinburgh Brain and Tissue Bank (EBTB), from 2005 to 2022, were analysed, using immunohistochemical analysis on fixed tissue, and five biochemical tests on frozen specimens from six brain regions, based on different principles for detecting PrPSc . An algorithm was established for classifying the biochemical results. To test the effectiveness of the protocol, several neuropathologically confirmed prion disease controls, including vCJD, were included and blinded in the study cohort. On unblinding, all the positive control cases had been correctly identified. No other cases tested positive; our analysis uncovered no overlooked prion disease cases. Our algorithm for classifying cases was effective for handling anomalous biochemical results. An overall analysis suggested that a reduced biochemical protocol employing only three of the five tests on only two brain tissue regions gave sufficient sensitivity and specificity. We conclude that this protocol may be useful as a UK-wide screening programme for human prion disease in selected brains from autopsies in the elderly. Further improvements to the protocol were suggested by enhancements of the in vitro conversion assays made during the course of this study.

Conservation of vCJD Strain Properties After Extraction and In Vitro Propagation of PrPSc from Archived Formalin-Fixed Brain and Appendix Tissues Using Highly Sensitive Protein Misfolding Cyclic Amplification.

Three retrospective lymphoreticular tissue studies (Appendix I, II, and III) aimed to estimate the UK prevalence of variant Creutzfeldt-Jakob disease (vCJD), following exposure of the population to the bovine spongiform encephalopathy (BSE) agent, in the late 1980s and 1990s. These studies evaluated the presence of abnormal prion protein aggregates, in archived formalin-fixed paraffin-embedded (FFPE) appendectomy samples, by immunohistochemical detection. Although there was concordance in the estimated prevalence of vCJD from these studies, the identification of positive specimens from pre- and post-BSE-exposure periods in Appendix III study has raised questions regarding the nature and origin of the detected abnormal prion protein. We applied a robust and novel approach in the extraction of disease-associated prion protein (PrPSc) present in frozen and FFPE samples of brain and appendix from a patient with pathologically confirmed vCJD. The extracted material was used to seed the highly sensitive protein misfolding cyclic amplification assay (hsPMCA) to investigate the in vitro and in vivo propagation properties of the extracted abnormal prion protein. We demonstrate that PrPSc can be successfully extracted from FFPE appendix tissue and propagated in vitro. Bioassay in wild-type and gene-targeted mouse models confirmed that the extracted and amplified product is infectious and retains strain properties consistent with vCJD. This provides a highly sensitive and reliable platform for subsequent analysis of the archived FFPE appendix tissue derived from the Appendix II and III surveys, to further evaluate the nature of the abnormal PrP detected in the positive samples.

Variant CJD: Reflections a Quarter of a Century on.

Twenty-five years has now passed since variant Creutzfeldt-Jakob disease (vCJD) was first described in the United Kingdom (UK). Early epidemiological, neuropathological and biochemical investigations suggested that vCJD represented a new zoonotic form of human prion disease resulting from dietary exposure to the bovine spongiform encephalopathy (BSE) agent. This hypothesis has since been confirmed though a large body of experimental evidence, predominantly using animal models of the disease. Today, the clinical, pathological and biochemical phenotype of vCJD is well characterized and demonstrates a unique and remarkably consistent pattern between individual cases when compared to other human prion diseases. While the numbers of vCJD cases remain reassuringly low, with 178 primary vCJD cases reported in the UK and a further 54 reported worldwide, concerns remain over the possible appearance of new vCJD cases in other genetic cohorts and the numbers of asymptomatic individuals in the population harboring vCJD infectivity. This review will provide a historical perspective on vCJD, examining the origins of this acquired prion disease and its association with BSE. We will investigate the epidemiology of the disease along with the unique clinicopathological and biochemical phenotype associated with vCJD cases. Additionally, this review will examine the impact vCJD has had on public health in the UK and the ongoing concerns raised by this rare group of disorders.

Prion strains associated with iatrogenic CJD in French and UK human growth hormone recipients.

Treatment with human pituitary-derived growth hormone (hGH) was responsible for a significant proportion of iatrogenic Creutzfeldt-Jakob disease (iCJD) cases. France and the UK experienced the largest case numbers of hGH-iCJD, with 122 and 81 cases respectively. Differences in the frequency of the three PRNP codon 129 polymorphisms (MM, MV and VV) and the estimated incubation periods associated with each of these genotypes in the French and the UK hGH-iCJD cohorts led to the suggestion that the prion strains responsible for these two hGH-iCJD cohorts were different. In this study, we characterized the prion strains responsible for hGH-iCJD cases originating from UK (n = 11) and France (n = 11) using human PrP expressing mouse models. The cases included PRNP MM, MV and VV genotypes from both countries. UK and French sporadic CJD (sCJD) cases were included as controls. The prion strains identified following inoculation with hGH-iCJD homogenates corresponded to the two most frequently observed sCJD prion strains (M1CJD and V2CJD). However, in clear contradiction to the initial hypothesis, the prion strains that were identified in the UK and the French hGH-iCJD cases were not radically different. In the vast majority of the cases originating from both countries, the V2CJD strain or a mixture of M1CJD + V2CJD strains were identified. These data strongly support the contention that the differences in the epidemiological and genetic profiles observed in the UK and France hGH-iCJD cohorts cannot be attributed only to the transmission of different prion strains.

Phenotypic diversity of genetic Creutzfeldt-Jakob disease: a histo-molecular-based classification.

The current classification of sporadic Creutzfeldt-Jakob disease (sCJD) includes six major clinicopathological subtypes defined by the physicochemical properties of the protease-resistant core of the pathologic prion protein (PrPSc), defining two major PrPSc types (i.e., 1 and 2), and the methionine (M)/valine (V) polymorphic codon 129 of the prion protein gene (PRNP). How these sCJD subtypes relate to the well-documented phenotypic heterogeneity of genetic CJD (gCJD) is not fully understood. We analyzed molecular and phenotypic features in 208 individuals affected by gCJD, carrying 17 different mutations, and compared them with those of a large series of sCJD cases. We identified six major groups of gCJD based on the combination PrPSc type and codon 129 genotype on PRNP mutated allele, each showing distinctive histopathological characteristics, irrespectively of the PRNP associated mutation. Five gCJD groups, named M1, M2C, M2T, V1, and V2, largely reproduced those previously described in sCJD subtypes. The sixth group shared phenotypic traits with the V2 group and was only detected in patients carrying the E200K-129M haplotype in association with a PrPSc type of intermediate size ("i") between type 1 and type 2. Additional mutation-specific effects involved the pattern of PrP deposition (e.g., a "thickened" synaptic pattern in E200K carriers, cerebellar "stripe-like linear granular deposits" in those with insertion mutations, and intraneuronal globular dots in E200K-V2 or -M"i"). A few isolated cases linked to rare PRNP haplotypes (e.g., T183A-129M), showed atypical phenotypic features, which prevented their classification into the six major groups. The phenotypic variability of gCJD is mostly consistent with that previously found in sCJD. As in sCJD, the codon 129 genotype and physicochemical properties of PrPSc significantly correlated with the phenotypic variability of gCJD. The most common mutations linked to CJD appear to have a variable and overall less significant effect on the disease phenotype, but they significantly influence disease susceptibility often in a strain-specific manner. The criteria currently used for sCJD subtypes can be expanded and adapted to gCJD to provide an updated classification of the disease with a molecular basis.

Fatal insomnia: the elusive prion disease.

A previously well 54- year-old woman presented with a short history of diplopia, cognitive decline, hallucinations and hypersomnolence. The patient had progressive deterioration in short-term memory, ocular convergence spasm, tremor, myoclonus, gait apraxia, central fever, dream enactment and seizures. Results of investigations were normal including MRI brain, electroencephalogram, cerebrospinal fluid (CSF, including CSF prion protein markers) and brain biopsy. The patient died from pneumonia and pulmonary embolus. Brain postmortem analysis revealed neuropathological changes in keeping with Fatal familial insomnia (FFI); the diagnosis was confirmed on genetic testing. FFI is caused by an autosomal dominant and highly penetrant pathogenic Prion Protein gene PRNP Although usually familial, fatal insomnia (FI) also occurs in a rare sporadic form. FI is a rare human prion disease with prominent sleep disturbance, autonomic, motor, cognitive and behavioural involvement. Patient management is with best supportive care and early suspected diagnosis allows for timely palliation.

Novel Morphological Glial Alterations in the Spectrum of Prion Disease Types: A Focus on Common Findings.

Human prion diseases are a group of rare fatal neurodegenerative diseases with sporadic, genetic, and acquired forms. They are neuropathologically characterized by pathological prion protein accumulation, neuronal death, and vacuolation. Classical immunological response has long been known not to play a major in prion diseases; however, gliosis is known to be a common feature although variable in extent and poorly described. In this investigation, astrogliosis and activated microglia in two brain regions were assessed and compared with non-neurologically affected patients in a representative sample across the spectrum of Creutzfeldt-Jakob disease (CJD) forms and subtypes in order to analyze the influence of prion strain on pathological processes. In this report, we choose to focus on features common to all CJD types rather than the diversity among them. Novel pathological changes in both glial cell types were found to be shared by all CJD types. Microglial activation correlated to astrogliosis. Spongiosis, but not pathological prion protein deposition, correlated to both astrogliosis and microgliosis. At the ultrastructural level, astrocytic glial filaments correlated with pathological changes associated with prion disease. These observations confirm that neuroglia play a prominent role in the neurodegenerative process of prion diseases, regardless of the causative prion type.

Prion Diseases: A Unique Transmissible Agent or a Model for Neurodegenerative Diseases?

The accumulation and propagation in the brain of misfolded proteins is a pathological hallmark shared by many neurodegenerative diseases such as Alzheimer's disease (Aß and tau), Parkinson's disease (α-synuclein), and prion disease (prion protein). Currently, there is no epidemiological evidence to suggest that neurodegenerative disorders are infectious, apart from prion diseases. However, there is an increasing body of evidence from experimental models to suggest that other pathogenic proteins such as Aß and tau can propagate in vivo and in vitro in a prion-like mechanism, inducing the formation of misfolded protein aggregates such as amyloid plaques and neurofibrillary tangles. Such similarities have raised concerns that misfolded proteins, other than the prion protein, could potentially transmit from person-to-person as rare events after lengthy incubation periods. Such concerns have been heightened following a number of recent reports of the possible inadvertent transmission of Aß pathology via medical and surgical procedures. This review will provide a historical perspective on the unique transmissible nature of prion diseases, examining their impact on public health and the ongoing concerns raised by this rare group of disorders. Additionally, this review will provide an insight into current evidence supporting the potential transmissibility of other pathogenic proteins associated with more common neurodegenerative disorders and the potential implications for public health.

Transmission characteristics of heterozygous cases of Creutzfeldt-Jakob disease with variable abnormal prion protein allotypes.

In the human prion disease Creutzfeldt-Jakob disease (CJD), different CJD neuropathological subtypes are defined by the presence in normal prion protein (PrPC) of a methionine or valine at residue 129, by the molecular mass of the infectious prion protein PrPSc, by the pattern of PrPSc deposition, and by the distribution of spongiform change in the brain. Heterozygous cases of CJD potentially add another layer of complexity to defining CJD subtypes since PrPSc can have either a methionine (PrPSc-M129) or valine (PrPSc-V129) at residue 129. We have recently demonstrated that the relative amount of PrPSc-M129 versus PrPSc-V129, i.e. the PrPSc allotype ratio, varies between heterozygous CJD cases. In order to determine if differences in PrPSc allotype correlated with different disease phenotypes, we have inoculated 10 cases of heterozygous CJD (7 sporadic and 3 iatrogenic) into two transgenic mouse lines overexpressing PrPC with a methionine at codon 129. In one case, brain-region specific differences in PrPSc allotype appeared to correlate with differences in prion disease transmission and phenotype. In the other 9 cases inoculated, the presence of PrPSc-V129 was associated with plaque formation but differences in PrPSc allotype did not consistently correlate with disease incubation time or neuropathology. Thus, while the PrPSc allotype ratio may contribute to diverse prion phenotypes within a single brain, it does not appear to be a primary determinative factor of disease phenotype.

Study protocol for enhanced CJD surveillance in the 65+ years population group in Scotland: an observational neuropathological screening study of banked brain tissue donations for evidence of prion disease.

INTRODUCTION: Creutzfeldt-Jakob disease (CJD) is a human prion disease that occurs in sporadic, genetic and acquired forms. Variant CJD (vCJD) is an acquired form first identified in 1996 in the UK. To date, 178 cases of vCJD have been reported in the UK, most of which have been associated with dietary exposure to the bovine spongiform encephalopathy agent. Most vCJD cases have a young age of onset, with a median age at death of 28 years. In the UK, suspected cases of vCJD are reported to the UK National Creutzfeldt-Jakob Disease Research & Surveillance Unit (NCJDRSU). There is, however, a concern that the national surveillance system might be missing some cases of vCJD or other forms of human prion disease, particularly in the older population, perhaps because of atypical clinical presentation. This study aims to establish whether there is unrecognised prion disease in people aged 65 years and above in the Scottish population by screening banked brain tissue donated to the Edinburgh Brain Bank (EBB). METHODS: Neuropathological screening of prospective and retrospective brain tissue samples is performed. This involves histopathological and immunohistochemical analysis and prion protein biochemical analysis. During the study, descriptive statistics are used to describe the study population, including the demographics and clinical, pathological and referral characteristics. Controlling for confounders, univariate and multivariate analyses will be used to compare select characteristics of newly identified suspect cases with previously confirmed cases referred to the NCJDRSU. ETHICS AND DISSEMINATION: Brain tissue donations to EBB are made voluntarily by the relatives of patients, with consent for use in research. The EBB has ethical approval to provide tissue samples to research projects (REC reference 16/ES/0084). The findings of this study will be disseminated in meetings, conferences, workshops and as peer-reviewed publications. TRIAL REGISTRATION NUMBERS: 10/S1402/69 and 10/S1402/70.

Sporadic Fatal Insomnia in Europe: Phenotypic Features and Diagnostic Challenges.

OBJECTIVE: Comprehensively describe the phenotypic spectrum of sporadic fatal insomnia (sFI) to facilitate diagnosis and management of this rare and peculiar prion disorder. METHODS: A survey among major prion disease reference centers in Europe identified 13 patients diagnosed with sFI in the past 20 years. We undertook a detailed analysis of clinical and histopathological features and the results of diagnostic investigations. RESULTS: Mean age at onset was 43 years, and mean disease duration 30 months. Early clinical findings included psychiatric, sleep, and oculomotor disturbances, followed by cognitive decline and postural instability. In all tested patients, video-polysomnography demonstrated a severe reduction of total sleep time and/or a disorganized sleep. Cerebrospinal fluid (CSF) levels of proteins 14-3-3 and t-tau were unrevealing, the concentration of neurofilament light protein (NfL) was more consistently increased, and the real-time quaking-induced conversion assay (RT-QuIC) revealed a positive prion seeding activity in 60% of cases. Electroencephalography and magnetic resonance imaging showed nonspecific findings, whereas fluorodeoxyglucose positron emission tomography (FDG-PET) demonstrated a profound bilateral thalamic hypometabolism in 71% of cases. Molecular analyses revealed PrPSc type 2 and methionine homozygosity at PRNP codon 129 in all cases. INTERPRETATION: sFI is a disease of young or middle-aged adults, which is difficult to reconcile with the hypothesis of a spontaneous etiology related to stochastic, age-related PrP misfolding. The combination of psychiatric and/or sleep-related symptoms with oculomotor abnormalities represents an early peculiar clinical feature of sFI to be valued in the differential diagnosis. Video-polysomnography, FDG-PET, and especially CSF prion RT-QuIC and NfL constitute the most promising supportive diagnostic tests in vivo. Ann Neurol 2018;84:347-360.

Prion diseases.

The human prion diseases comprise Creutzfeldt-Jakob disease, variably protease-sensitive prionopathy, Gerstmann-Sträussler-Scheinker disease, fatal familial insomnia, and kuru. Each is a uniformly fatal rare neurodegenerative disease in which conformational changes in the prion protein are thought to be the central pathophysiologic event. The majority of cases of human prion diseases occur worldwide in the form of sporadic Creutzfeldt-Jakob disease and a minority of around 10-15% are associated with mutations of the prion protein gene, termed PRNP, in the forms of genetic Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker disease, and fatal familial insomnia. Prion diseases are also transmissible and occur in iatrogenic and zoonotic forms (iatrogenic Creutzfeldt-Jakob disease and variant Creutzfeldt-Jakob disease respectively), adding a public health dimension to their management. Despite having a high public profile, human prion diseases are both rare and heterogeneous in their clinicopathologic phenotype, sometimes making a diagnosis challenging. A combined clinical, genetic, neuropathologic, and biochemical approach to diagnosis is therefore essential. The intensive study of these diseases continues to inform on neurodegenerative mechanisms and the role of protein misfolding in more common neurodegenerative diseases such as Parkinson disease and Alzheimer disease.

Neuropathology of Human Prion Diseases.

The human prion diseases comprise sporadic, genetic, and acquired disorders. These are rare conditions with a heterogeneous clinicopathologic phenotype, which can make diagnosis challenging. A combined clinical, genetic, neuropathologic and biochemical approach to diagnosis is therefore essential. Since prion infectivity is the highest in tissues from the central nervous system, special laboratory precautions are required for the safe handling of these tissues. Neuropathologic assessment is generally performed following autopsy, when the fixed brain should be adequately sampled and studied by conventional stains and immunohistochemistry for the abnormal form of the prion protein. Frozen brain tissue is also required for DNA extraction for prion protein gene sequencing and for Western blot analysis of protease-resistant prion protein. The microscopic assessment of the nature and degree of spongiform change, neuronal loss, gliosis, and abnormal prion protein deposition in the brain can be used to determine the major categories of human prion disease. This information can be combined with clinical, genetic data, and biochemical data to allow an accurate diagnosis of a human prion disease and facilitates subclassification into recognized disease subtypes, for example in sporadic Creutzfeldt-Jakob disease. The spectrum of human prion diseases continues to expand and neuropathology will play a key role in the recognition and understanding of any further novel entities or disease variants that may emerge in the future.

Amyloid-ß accumulation in the CNS in human growth hormone recipients in the UK.

Human-to-human transmission of Creutzfeldt-Jakob disease (CJD) has occurred through medical procedures resulting in iatrogenic CJD (iCJD). One of the commonest causes of iCJD was the use of human pituitary-derived growth hormone (hGH) to treat primary or secondary growth hormone deficiency. As part of a comprehensive tissue-based analysis of the largest cohort yet collected (35 cases) of UK hGH-iCJD cases, we describe the clinicopathological phenotype of hGH-iCJD in the UK. In the 33/35 hGH-iCJD cases with sufficient paraffin-embedded tissue for full pathological examination, we report the accumulation of the amyloid beta (Aß) protein associated with Alzheimer's disease (AD) in the brains and cerebral blood vessels in 18/33 hGH-iCJD patients and for the first time in 5/12 hGH recipients who died from causes other than CJD. Aß accumulation was markedly less prevalent in age-matched patients who died from sporadic CJD and variant CJD. These results are consistent with the hypothesis that Aß, which can accumulate in the pituitary gland, was present in the inoculated hGH preparations and had a seeding effect in the brains of around 50% of all hGH recipients, producing an AD-like neuropathology and cerebral amyloid angiopathy (CAA), regardless of whether CJD neuropathology had occurred. These findings indicate that Aß seeding can occur independently and in the absence of the abnormal prion protein in the human brain. Our findings provide further evidence for the prion-like seeding properties of Aß and give insights into the possibility of iatrogenic transmission of AD and CAA.

UK Iatrogenic Creutzfeldt-Jakob disease: investigating human prion transmission across genotypic barriers using human tissue-based and molecular approaches.

Creutzfeldt-Jakob disease (CJD) is the prototypic human prion disease that occurs most commonly in sporadic and genetic forms, but it is also transmissible and can be acquired through medical procedures, resulting in iatrogenic CJD (iCJD). The largest numbers of iCJD cases that have occurred worldwide have resulted from contaminated cadaveric pituitary-derived human growth hormone (hGH) and its use to treat primary and secondary growth hormone deficiency. We report a comprehensive, tissue-based and molecular genetic analysis of the largest series of UK hGH-iCJD cases reported to date, including in vitro kinetic molecular modelling of genotypic factors influencing prion transmission. The results show the interplay of prion strain and host genotype in governing the molecular, pathological and temporal characteristics of the UK hGH-iCJD epidemic and provide insights into the adaptive mechanisms involved when prions cross genotypic barriers. We conclude that all of the available evidence is consistent with the hypothesis that the UK hGH-iCJD epidemic resulted from transmission of the V2 human prion strain, which is associated with the second most common form of sporadic CJD.

Relative Abundance of apoE and Aß1-42 Associated with Abnormal Prion Protein Differs between Creutzfeldt-Jakob Disease Subtypes.

Aggregated and protease-resistant mammalian prion protein (PrPSc) is the primary protein component of infectious prions. Enriched PrPSc preparations are often used to study the mechanisms that underly prion disease. However, most enrichment procedures are relatively nonspecific and tend to yield significant amounts of non-PrPSc components including various proteins that could confound functional and structural studies. It is thus important to identify these proteins and assess their potential relevance to prion pathogenesis. Following proteinase K treatment and phosphotungstic acid precipitation of brain homogenate, we have used mass spectrometry to analyze the protein content of PrPSc isolated from prion-infected mice, multiple cases of sporadic Creutzfeldt-Jakob disease (sCJD), and human growth hormone associated cases of iatrogenic CJD (iCJD). Creatine kinase was the primary protein contaminant in all PrPSc samples, while many of the other proteins identified were also found in non-CJD controls, which suggests that they are not CJD specific. Interestingly, the Alzheimer's disease associated peptide amyloid ß 1-42 (Aß1-42) was identified in the majority of the sCJD cases as well as non-CJD age-matched controls, while apoliprotein E was found in greater abundance in the sCJD cases. By contrast, while some of the iCJD cases showed evidence of higher molecular weight Aß oligomers, monomeric Aß1-42 peptide was not detected by immunoblot, and only one case had significant levels of apolipoprotein E. Our data are consistent with the age-associated deposition of Aß1-42 in older sporadic CJD and non-CJD patients and suggest that both apolipoprotein E and Aß1-42 abundance can differ depending upon the type of CJD.

The Distribution of Prion Protein Allotypes Differs Between Sporadic and Iatrogenic Creutzfeldt-Jakob Disease Patients.

Sporadic Creutzfeldt-Jakob disease (sCJD) is the most prevalent of the human prion diseases, which are fatal and transmissible neurodegenerative diseases caused by the infectious prion protein (PrP(Sc)). The origin of sCJD is unknown, although the initiating event is thought to be the stochastic misfolding of endogenous prion protein (PrP(C)) into infectious PrP(Sc). By contrast, human growth hormone-associated cases of iatrogenic CJD (iCJD) in the United Kingdom (UK) are associated with exposure to an exogenous source of PrP(Sc). In both forms of CJD, heterozygosity at residue 129 for methionine (M) or valine (V) in the prion protein gene may affect disease phenotype, onset and progression. However, the relative contribution of each PrP(C) allotype to PrP(Sc) in heterozygous cases of CJD is unknown. Using mass spectrometry, we determined that the relative abundance of PrP(Sc) with M or V at residue 129 in brain specimens from MV cases of sCJD was highly variable. This result is consistent with PrP(C) containing an M or V at residue 129 having a similar propensity to misfold into PrP(Sc) thus causing sCJD. By contrast, PrP(Sc) with V at residue 129 predominated in the majority of the UK human growth hormone associated iCJD cases, consistent with exposure to infectious PrP(Sc) containing V at residue 129. In both types of CJD, the PrP(Sc) allotype ratio had no correlation with CJD type, age at clinical onset, or disease duration. Therefore, factors other than PrP(Sc) allotype abundance must influence the clinical progression and phenotype of heterozygous cases of CJD.

Blood transmission studies of prion infectivity in the squirrel monkey (Saimiri sciureus): the Baxter study.

BACKGROUND: Four secondary transmissions of variant Creutzfeldt-Jakob disease (vCJD) infectivity have been associated with the transfusion of nonleukoreduced red blood cells collected from vCJD patients during the asymptomatic phase of the disease. Establishing efficient experimental models for assessing the risk of future transmissions of vCJD infectivity via blood transfusion is of paramount importance in view of a study of archived appendix samples in which the prevalence of asymptomatic vCJD infection in the United Kingdom was estimated at approximately 1 in 2000 of the population. In this study, we investigated transmission of vCJD and sporadic CJD (sCJD) infectivity from blood using the squirrel monkey, which is highly susceptible to experimental challenge with human prion disease. STUDY DESIGN AND METHODS: Whole blood collected from vCJD- and sCJD-infected squirrel monkeys was transfused at multiple time points into recipient squirrel monkeys. Blood recipients were euthanized approximately 7 years after their first blood transfusion. RESULTS: No clinical or pathologic signs of a prion disease were observed in either the sCJD- or the vCJD-transfused monkeys, and immunohistochemistry and biochemical investigations showed no PrP(TSE) in central nervous system or lymphoreticular tissues. Similarly, monkeys inoculated intracerebrally (IC) and intravenously (IV) with either buffy coat or plasma from vCJD and sCJD patients failed to develop disease. However, white blood cells from a chimpanzee-passaged strain of human Gerstmann-Sträussler-Scheinker (GSS) disease transmitted autopsy-proven disease to two IC-inoculated monkeys after incubation periods of 34 and 39 months. CONCLUSION: Blood transmits GSS but not sCJD or vCJD infectivity to IC- or IV-inoculated squirrel monkeys within a 7-year observation period.

A Naturally Occurring Bovine Tauopathy Is Geographically Widespread in the UK.

Many human neurodegenerative diseases are associated with hyperphosphorylation and widespread intra-neuronal and glial associated aggregation of the microtubule associated protein tau. In contrast, animal tauopathies are not reported with only senescent animals showing inconspicuous tau labelling of fine processes albeit significant tau aggregation may occur in some experimental animal disease. Since 1986, an idiopathic neurological condition of adult cattle has been recognised in the UK as a sub-set of cattle slaughtered as suspect bovine spongiform encephalopathy cases. This disorder is characterised by brainstem neuronal chromatolysis and degeneration with variable hippocampal sclerosis and spongiform change. Selected cases of idiopathic brainstem neuronal chromatolysis (IBNC) were identified from archive material and characterised using antibodies specific to several tau hyperphosphorylation sites or different isoforms of the tau microtubule binding region. Labelling was also carried out for alpha synuclein, ubiquitin, TDP43, Aß 1-42, Aß 1-40. Widespread tau labelling was identified in all IBNC brains examined and with each of seven tau antibodies recognising different hyperphosphorylated sites. Labelling with each antibody was associated with dendrites, neuronal perikarya and glia. Thus IBNC is a sporadic, progressive neurological disease predominantly affecting aged cattle that occurs throughout the UK and is associated with hyperphosphorylation of tau, a rare example of a naturally-occurring tauopathy in a non-primate species. Secondary accumulation of alpha synuclein and ubiquitin was also present. The neuropathology does not precisely correspond with any human tauopathy. The cause of IBNC remains undetermined but environmental factors and exposure to agrochemicals needs to be considered in future aetiological investigations.