Assessment of the Zoonotic Potential of Atypical Scrapie Prions in Humanized Mice Reveals Rare Phenotypic Convergence but Not Identity With Sporadic Creutzfeldt-Jakob Disease Prions.

BACKGROUND: Atypical/Nor98 scrapie (AS) is an idiopathic infectious prion disease affecting sheep and goats. Recent findings suggest that zoonotic prions from classical bovine spongiform encephalopathy (C-BSE) may copropagate with atypical/Nor98 prions in AS sheep brains. Investigating the risk AS poses to humans is crucial. METHODS: To assess the risk of sheep/goat-to-human transmission of AS, we serially inoculated brain tissue from field and laboratory isolates into transgenic mice overexpressing human prion protein (Met129 allele). We studied clinical outcomes as well as presence of prions in brains and spleens. RESULTS: No transmission occurred on the primary passage, with no clinical disease or pathological prion protein in brains and spleens. On subsequent passages, 1 isolate gradually adapted, manifesting as prions with a phenotype resembling those causing MM1-type sporadic Creutzfeldt-Jakob disease in humans. However, further characterization using in vivo and in vitro techniques confirmed both prion agents as different strains, revealing a case of phenotypic convergence. Importantly, no C-BSE prions emerged in these mice, especially in the spleen, which is more permissive than the brain for C-BSE cross-species transmission. CONCLUSIONS: The results obtained suggest a low zoonotic potential for AS. Rare adaptation may allow the emergence of prions phenotypically resembling those spontaneously forming in humans.

Glycans are not necessary to maintain the pathobiological features of bovine spongiform encephalopathy.

The role of the glycosylation status of PrPC in the conversion to its pathological counterpart and on cross-species transmission of prion strains has been widely discussed. Here, we assessed the effect on strain characteristics of bovine spongiform encephalopathy (BSE) isolates with different transmission histories upon propagation on a model expressing a non-glycosylated human PrPC. Bovine, ovine and porcine-passaged BSE, and variant Creutzfeldt-Jakob disease (vCJD) isolates were used as seeds/inocula in both in vitro and in vivo propagation assays using the non-glycosylated human PrPC-expressing mouse model (TgNN6h). After protein misfolding cyclic amplification (PMCA), all isolates maintained the biochemical characteristics of BSE. On bioassay, all PMCA-propagated BSE prions were readily transmitted to TgNN6h mice, in agreement with our previous in vitro results. TgNN6h mice reproduced the characteristic neuropathological and biochemical hallmarks of BSE, suggesting that the absence of glycans did not alter the pathobiological features of BSE prions. Moreover, back-passage of TgNN6h-adapted BSE prions to BoTg110 mice recovered the full BSE phenotype, confirming that the glycosylation of human PrPC is not essential for the preservation of the human transmission barrier for BSE prions or for the maintenance of BSE strain properties.

Classical BSE dismissed as the cause of CWD in Norwegian red deer despite strain similarities between both prion agents.

The first case of CWD in a Norwegian red deer was detected by a routine ELISA test and confirmed by western blotting and immunohistochemistry in the brain stem of the animal. Two different western blotting tests were conducted independently in two different laboratories, showing that the red deer glycoprofile was different from the Norwegian CWD reindeer and CWD moose and from North American CWD. The isolate showed nevertheless features similar to the classical BSE (BSE-C) strain. Furthermore, BSE-C could not be excluded based on the PrPSc immunohistochemistry staining in the brainstem and the absence of detectable PrPSc in the lymphoid tissues. Because of the known ability of BSE-C to cross species barriers as well as its zoonotic potential, the CWD red deer isolate was submitted to the EURL Strain Typing Expert Group (STEG) as a BSE-C suspect for further investigation. In addition, different strain typing in vivo and in vitro strategies aiming at identifying the BSE-C strain in the red deer isolate were performed independently in three research groups and BSE-C was not found in it. These results suggest that the Norwegian CWD red deer case was infected with a previously unknown CWD type and further investigation is needed to determine the characteristics of this potential new CWD strain.

[Clinical characteristics and diagnostics of human spongiform encephalopathies: an update]. / Klinik und Diagnostik humaner spongiformer Enzephalopathien: ein Update.

Human spongiform encephalopathies are rare transmissible neurodegenerative diseases of the brain and the nervous system that are caused by misfolding of the physiological prion protein into a pathological form and its deposition in the central nervous system (CNS). Prion diseases include Creutzfeldt-Jakob disease (CJD, sporadic or familial), Gerstmann-Straussler-Scheinker syndrome (GSS) and fatal familial insomnia (FFI). Prion diseases can be differentiated into three etiological categories: spontaneous (sporadic CJD), inherited (familial CJD, FFI, and GSS) and acquired (variant CJD and iatrogenic CJD). Most cases occur sporadically. Prion diseases can lead to a variety of neurological symptoms and always have an inevitably fatal course. Cerebrospinal fluid analysis and magnetic resonance imaging (MRI) play a crucial role in the diagnostics of prion diseases and may facilitate an early and reliable clinical diagnosis. A causal treatment or specific therapeutic agents are not yet available. In general, a palliative therapeutic concept is indicated.

Preclinical transmission of prions by blood transfusion is influenced by donor genotype and route of infection.

Variant Creutzfeldt-Jakob disease (vCJD) is a human prion disease resulting from zoonotic transmission of bovine spongiform encephalopathy (BSE). Documented cases of vCJD transmission by blood transfusion necessitate on-going risk reduction measures to protect blood supplies, such as leucodepletion (removal of white blood cells, WBCs). This study set out to determine the risks of prion transmission by transfusion of labile blood components (red blood cells, platelets, plasma) commonly used in human medicine, and the effectiveness of leucodepletion in preventing infection, using BSE-infected sheep as a model. All components were capable of transmitting prion disease when donors were in the preclinical phase of infection, with the highest rates of infection in recipients of whole blood and buffy coat, and the lowest in recipients of plasma. Leucodepletion of components (<106 WBCs/unit) resulted in significantly lower transmission rates, but did not completely prevent transmission by any component. Donor PRNP genotype at codon 141, which is associated with variation in incubation period, also had a significant effect on transfusion transmission rates. A sensitive protein misfolding cyclic amplification (PMCA) assay, applied to longitudinal series of blood samples, identified infected sheep from 4 months post infection. However, in donor sheep (orally infected), the onset of detection of PrPSc in blood was much more variable, and generally later, compared to recipients (intravenous infection). This shows that the route and method of infection may profoundly affect the period during which an individual is infectious, and the test sensitivity required for reliable preclinical diagnosis, both of which have important implications for disease control. Our results emphasize that blood transfusion can be a highly efficient route of transmission for prion diseases. Given current uncertainties over the prevalence of asymptomatic vCJD carriers, this argues for the maintenance and improvement of current measures to reduce the risk of transmission by blood products.

The ultrastructure of infectious L-type bovine spongiform encephalopathy prions constrains molecular models.

Bovine spongiform encephalopathy (BSE) is a prion disease of cattle that is caused by the misfolding of the cellular prion protein (PrPC) into an infectious conformation (PrPSc). PrPC is a predominantly α-helical membrane protein that misfolds into a ß-sheet rich, infectious state, which has a high propensity to self-assemble into amyloid fibrils. Three strains of BSE prions can cause prion disease in cattle, including classical BSE (C-type) and two atypical strains, named L-type and H-type BSE. To date, there is no detailed information available about the structure of any of the infectious BSE prion strains. In this study, we purified L-type BSE prions from transgenic mouse brains and investigated their biochemical and ultrastructural characteristics using electron microscopy, image processing, and immunogold labeling techniques. By using phosphotungstate anions (PTA) to precipitate PrPSc combined with sucrose gradient centrifugation, a high yield of proteinase K-resistant BSE amyloid fibrils was obtained. A morphological examination using electron microscopy, two-dimensional class averages, and three-dimensional reconstructions revealed two structural classes of L-type BSE amyloid fibrils; fibrils that consisted of two protofilaments with a central gap and an average width of 22.5 nm and one-protofilament fibrils that were 10.6 nm wide. The one-protofilament fibrils were found to be more abundant compared to the thicker two-protofilament fibrils. Both fibrillar assemblies were successfully decorated with monoclonal antibodies against N- and C-terminal epitopes of PrP using immunogold-labeling techniques, confirming the presence of polypeptides that span residues 100-110 to 227-237. The fact that the one-protofilament fibrils contain both N- and C-terminal PrP epitopes constrains molecular models for the structure of the infectious conformer in favour of a compact four-rung ß-solenoid fold.

RT-QuIC as ultrasensitive method for prion detection.

Real-time quaking-induced conversion (RT-QuIC) is a cell-free abnormal form of prion protein (PrPSc) amplification method using recombinant prion protein from Escherichia coli that can measure prion seeding activity in samples with high sensitivity. The advantages of this method are that it is much more sensitive than Western blotting, which is usually used to detect PrPSc, and that prion seeding activity can be easily quantified by combining it with endpoint dilution of the sample, and that it can be amplified in most species and prion strains. A decade has passed since the development of RT-QuIC, and many studies have been reported that take advantage of its characteristics. In particular, its usefulness in the diagnosis of sporadic CJD has been clarified, and it is recommended to be one of the diagnostic criteria. Future challenges include the establishment of a method to differentiate prion strains and application of RT-QuIC to early diagnosis of prion diseases and determination of treatment efficacy.

Vaccines for prion diseases: a realistic goal?

Prion diseases are fatal infectious neurodegenerative disorders and prototypic conformational diseases, caused by the conformational conversion of the normal cellular prion protein (PrPC) into the pathological PrPSc isoform. Examples are scrapie in sheep and goat, bovine spongiform encephalopathy (BSE) in cattle, chronic wasting disease (CWD) in cervids, and Creutzfeldt-Jacob disease (CJD) in humans. There are no therapies available, and animal prion diseases like BSE and CWD can negatively affect the economy, ecology, animal health, and possibly human health. BSE is a confirmed threat to human health, and mounting evidence supports the zoonotic potential of CWD. CWD is continuously expanding in North America in numbers and distribution and was recently identified in Scandinavian countries. CWD is the only prion disease occurring both in wild and farmed animals, which, together with extensive shedding of infectivity into the environment, impedes containment strategies. There is currently a strong push to develop vaccines against CWD, including ones that can be used in wildlife. The immune system does not develop a bona fide immune response against prion infection, as PrPC and PrPSc share an identical protein primary structure, and prions seem not to represent a trigger for immune responses. This asks for alternative vaccine strategies, which focus on PrPC-directed self-antibodies or exposure of disease-specific structures and epitopes. Several groups have established a proof-of-concept that such vaccine candidates can induce some levels of protective immunity in cervid and rodent models without inducing unwanted side effects. This review will highlight the most recent developments and discuss progress and challenges remaining.

Experimental transmission of ovine atypical scrapie to cattle.

Classical bovine spongiform encephalopathy (BSE) in cattle was caused by the recycling and feeding of meat and bone meal contaminated with a transmissible spongiform encephalopathy (TSE) agent but its origin remains unknown. This study aimed to determine whether atypical scrapie could cause disease in cattle and to compare it with other known TSEs in cattle. Two groups of calves (five and two) were intracerebrally inoculated with atypical scrapie brain homogenate from two sheep with atypical scrapie. Controls were five calves intracerebrally inoculated with saline solution and one non-inoculated animal. Cattle were clinically monitored until clinical end-stage or at least 96 months post-inoculation (mpi). After euthanasia, tissues were collected for TSE diagnosis and potential transgenic mouse bioassay. One animal was culled with BSE-like clinical signs at 48 mpi. The other cattle either developed intercurrent diseases leading to cull or remained clinical unremarkable at study endpoint, including control cattle. None of the animals tested positive for TSEs by Western immunoblot and immunohistochemistry. Bioassay of brain samples from the clinical suspect in Ov-Tg338 and Bov-Tg110 mice was also negative. By contrast, protein misfolding cyclic amplification detected prions in the examined brains from atypical scrapie-challenged cattle, which had a classical BSE-like phenotype. This study demonstrates for the first time that a TSE agent with BSE-like properties can be amplified in cattle inoculated with atypical scrapie brain homogenate.

Detection of classical BSE prions in asymptomatic cows after inoculation with atypical/Nor98 scrapie.

The emergence of bovine spongiform encephalopathy (BSE) prions from atypical scrapie has been recently observed upon experimental transmission to rodent and swine models. This study aimed to assess whether the inoculation of atypical scrapie could induce BSE-like disease in cattle. Four calves were intracerebrally challenged with atypical scrapie. Animals were euthanized without clinical signs of prion disease and tested negative for PrPSc accumulation by immunohistochemistry and western blotting. However, an emergence of BSE-like prion seeding activity was detected during in vitro propagation of brain samples from the inoculated animals. These findings suggest that atypical scrapie may represent a potential source of BSE infection in cattle.

PRNP gene polymorphism frequencies for comparing possible vulnerability to BSE in Chinese bovine population.

Among the numerous transmissible spongiform encephalopathies (TSEs), bovine spongiform encephalopathy (BSE) is the most well-known TSEs. It is a potential Creutzfeldt-Jakob (CJD) disease mutation that can be transferred through cattle to humans. In several animals, the prion protein gene (PRNP) is recognized to take active part in TSE vulnerability or tolerance. Previous studies have found indels polymorphism in PRNP gene promoter and intron1 region linked to BSE vulnerability. It's linked with 23 bp indels polymorphism in putative promoter and 12 bp indel in intron 1 of the PRNP gene. The aim of this study was to compare the allele, genotype and haplotype frequencies of PRNP indel polymorphisms in Zhongdian Yak (Bos grunniens) (YK), Zhongdian Yellow cattle (Bos taurus) (YC) and Zhongdian Yakow (Bos primigenius taurus × Bos grunniens) (PK) with worldwide reported healthy or affected BSE cattle, in order to assess their potential resistance to BSE. A comparison of Chinese bovine populations with healthy and BSE-affected German and Swiss cattle from globally was conducted, and result indicating significant difference (p < .001) between healthy and affected cattle. Additionally, as compared to prior studies with Chinese bovine population, the significant results were found. In this study, the allelic frequency D23 finding high deletion in all analyzed Chinese bovine species, and haplotype D12-D23 exhibited a less significant inclination toward susceptibility to BSE.

Low frequency of protective variants at regulatory region of PRNP gene indicating the genetically high risk of BSE in Ethiopian Bos indicus and Bos taurus africanus.

Susceptibility to classical bovine spongiform encephalopathy (BSE) has been linked to 23 bp indel in promoter and 12 bp indel in the first intron of cattle prion protein gene. This study aimed to investigate 23/12 bp indel polymorphisms in the polymorphisms in cattle prion protein (PRNP) gene to reveal the risk of BSE in Ethiopian cattle. Also, frequency of each polymorphism was compared to the other Bos taurus and Bos indicus breeds. According to results, the insertion variant was detected at a low frequency in all of the study populations at both loci. The 23 bp insertion allele in Fogera breed was relatively lower than Borona and Arsi and the same allele at the same locus in Afar breed was higher than the rest of the breeds (0.16). Due to high linkage disequilibrium (LD) of the deletion allele in Bos taurus, the frequencies of deletion allele at 23 bp (0.84) and 12 bp (0.86) loci in Afar breed were relatively closer than the rest of the breeds. In addition, DD/DD was found as the highly frequent diplotype in all of the breeds. The low frequency of insertion alleles at 23 and 12 bp indel sites demonstrate that Ethiopian cattle have a genetically high risk for BSE.

Conventional and State-of-the-Art Detection Methods of Bovine Spongiform Encephalopathy (BSE).

Bovine spongiform encephalopathy (BSE) is a fatal neurodegenerative disease that belongs to a group of diseases known as transmissible spongiform encephalopathies (TSEs). It is believed that the infectious agent responsible for prion diseases is abnormally folded prion protein (PrPSc), which derives from a normal cellular protein (PrPC), which is a cell surface glycoprotein predominantly expressed in neurons. There are three different types of BSE, the classical BSE (C-type) strain and two atypical strains (H-type and L-type). BSE is primarily a disease of cattle; however, sheep and goats also can be infected with BSE strains and develop a disease clinically and pathogenically indistinguishable from scrapie. Therefore, TSE cases in cattle and small ruminants require discriminatory testing to determine whether the TSE is BSE or scrapie and to discriminate classical BSE from the atypical H- or L-type strains. Many methods have been developed for the detection of BSE and have been reported in numerous studies. Detection of BSE is mainly based on the identification of characteristic lesions or detection of the PrPSc in the brain, often by use of their partial proteinase K resistance properties. The objective of this paper was to summarize the currently available methods, highlight their diagnostic performance, and emphasize the advantages and drawbacks of the application of individual tests.

A new model for sensitive detection of zoonotic prions by PrP transgenic Drosophila.

Prions are transmissible protein pathogens most reliably detected by a bioassay in a suitable host, typically mice. However, the mouse bioassay is slow and cumbersome, and relatively insensitive to low titers of prion infectivity. Prions can be detected biochemically in vitro by the protein misfolding cyclic amplification (PMCA) technique, which amplifies disease-associated prion protein but does not detect bona fide prion infectivity. Here, we demonstrate that Drosophila transgenic for bovine prion protein (PrP) expression can serve as a model system for the detection of bovine prions significantly more efficiently than either the mouse prion bioassay or PMCA. Strikingly, bovine PrP transgenic Drosophila could detect bovine prion infectivity in the region of a 10-12 dilution of classical bovine spongiform encephalopathy (BSE) inoculum, which is 106-fold more sensitive than that achieved by the bovine PrP mouse bioassay. A similar level of sensitivity was observed in the detection of H-type and L-type atypical BSE and sheep-passaged BSE by bovine PrP transgenic Drosophila. Bioassays of bovine prions in Drosophila were performed within 7 weeks, whereas the mouse prion bioassay required at least a year to assess the same inoculum. In addition, bovine PrP transgenic Drosophila could detect classical BSE at a level 105-fold lower than that achieved by PMCA. These data show that PrP transgenic Drosophila represent a new tractable prion bioassay for the efficient and sensitive detection of mammalian prions, including those of known zoonotic potential.

Methionine homozygosity for PRNP polymorphism and susceptibility to human prion diseases.

BACKGROUND: No studies have assessed the independent association of methionine homozygosity at codon 129 with the susceptibility to prion diseases, controlling for the effects of the codon 219 polymorphisms and other potential confounders, using a large-scale population-based dataset. METHODS: We conducted a case-control study using a Japanese nationwide surveillance database for prion diseases. The main exposure was methionine homozygosity at codon 129, and the outcome was development of prion diseases. Multivariable logistic regression models were employed for specific disease subtypes (sporadic Creutzfeldt-Jakob disease (CJD), genetic CJD and Gerstmann-Sträussler-Scheinker disease (GSS)). RESULTS: Of 5461 patients registered in the database, 2440 cases and 796 controls remained for the analysis. The cases comprised 1676 patients with sporadic CJD (69%), 649 with genetic CJD (27%) and 115 with GSS (5%). For patients with methionine homozygosity, potential risk for occurring prion diseases: adjusted OR (95% CI) was 2.21 (1.46 to 3.34) in sporadic CJD, 0.47 (0.32 to 0.68) in genetic CJD and 0.3 (0.17 to 0.55) in GSS. Among patients with specific prion protein abnormalities, the potential risk was 0.27 (0.17 to 0.41) in genetic CJD with 180 Val/Ile, 1.66 (0.65 to 5.58) in genetic CJD with 200 Glu/Lys, 3.97 (1.2 to 24.62) in genetic CJD with 232 Met/Arg and 0.71 (0.34 to 1.67) in GSS with 102 Pro/Leu. CONCLUSIONS: Methionine homozygosity at codon 129 was predisposing to sporadic CJD, but protective against genetic CJD and GSS, after adjustment for codon 219 polymorphism effect. However, the impacts differed completely among patients with specific prion protein abnormalities.

Extended application of the rapid post-mortem test kit for bovine spongiform encephalopathy to chronic wasting disease.

Chronic wasting disease (CWD) is a prion disease affecting cervid species primarily in the United States of America and Canada; however, it is now emerging in Scandinavian countries. Although CWD cases have not been reported in Japan, in case of a CWD outbreak occuring, it is critical to prepare for testing a large number of specimens. The present study showed that a rapid post-mortem test kit, which is used for bovine spongiform encephalopathy surveillance in Japan, is valid for the detection of CWD prion.

Synthesis and Characterization of Hydroxyethylamino- and Pyridyl-Substituted 2-Vinyl Chromone Derivatives for Detection of Cerebral Abnormal Prion Protein Deposits.

Prion diseases are fatal neurodegenerative diseases characterized by the deposition of abnormal prion protein aggregates (PrPSc) in the brain. In this study, we developed hydroxyethylamino-substituted styrylchromone (SC) and 2-(2-(pyridin-3-yl)vinyl)-4H-chromen-4-one (VPC) derivatives for single-photon emission computed tomography (SPECT) imaging of PrPSc deposits in the brain. The binding affinity of these compounds was evaluated using recombinant mouse prion protein (rMoPrP) aggregates, which resulted in the inhibition constant (Ki) value of 61.5 and 88.0 nM for hydroxyethyl derivative, (E)-2-(4-((2-hydroxyethyl)amino)styryl)-6-iodo-4H-chromen-4-one (SC-NHEtOH) and (E)-2-(4-((2-hydroxyethyl)(methyl)amino)styryl)-6-iodo-4H-chromen-4-one (SC-NMeEtOH), respectively. However, none of the VPC derivatives showed binding affinity for the rMoPrP aggregates. Fluorescent imaging demonstrated that the accumulation pattern of SC-NHEtOH matched with the presence of PrPSc in the brain slices from mouse-adapted bovine spongiform encephalopathy-infected mice. A biodistribution study of normal mice indicated low initial brain uptake of [125I]SC-NHEtOH (0.88% injected dose/g (% ID/g) at 2 min) despite favorable washout from the brain (0.26% ID/g, at 180 min) was displayed. [125I]SC-NHEtOH exhibited binding affinities to both artificial prion aggregates as well as prion deposits in the brain. However, significant improvement in the binding affinity for PrPSc and blood-brain barrier permeability is necessary for the development of successful in vivo imaging probes for the detection of cerebral PrPSc in the brain.

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

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

Prion Pathogenesis Revealed in a Series of the Special Issues "Prions and Prion Diseases".

Prion diseases are a group of devastating neurodegenerative disorders, which include Creutzfeldt-Jakob disease (CJD) in humans, and scrapie and bovine spongiform encephalopathy (BSE) in animals [...].

The First Evaluation of Proteinase K-Resistant Prion Protein (PrPSc) in Korean Appendix Specimens.

Background and Objectives: Prion diseases are fatal neurodegenerative disorders caused by the abnormal proteinase K-resistant prion protein (PrPSc). Since variant Creutzfeldt-Jakob disease (CJD) was first reported in the United Kingdom (UK) in 1996, the occurrence of variant CJD has been reported in over 10 countries. To date, variant CJD has not been reported in Korea. However, the E211K somatic mutation in the prion protein gene (PRNP), which is related to bovine spongiform encephalopathy (BSE), was reported in Korean Holstein cattle, and atypical BSE, which is supposed to be sporadic BSE, has been occurring in many countries, including Japan and the USA. These results suggest that BSE may occur naturally in Korea. Thus, we performed a preemptive PrPSc test in appendix specimens to diagnose variant CJD in a Korean population. Materials and Methods: In the present study, we investigated CJD-related mutations and polymorphisms of the PRNP gene and carried out an examination on PrPSc in appendix specimens of Korean patients after appendectomy. Results: In all Korean appendix specimens tested, PrPSc bands were not detected. Conclusion: To the best of our knowledge, this was the first evaluation of PrPSc in Korean appendix specimens.