Infectious Diseases of the Brain and Spine: Parasitic and Other Atypical Transmissible Diseases.

Atypical infections of the brain and spine caused by parasites occur in immunocompetent and immunosuppressed hosts, related to exposure and more prevalently in endemic regions. In the United States, the most common parasitic infections that lead to central nervous system manifestations include cysticercosis, echinococcosis, and toxoplasmosis, with toxoplasmosis being the most common opportunistic infection affecting patients with advanced HIV/AIDS. Another rare but devastating transmittable disease is prion disease, which causes rapidly progressive spongiform encephalopathies. Familiarity and understanding of various infectious agents are a crucial aspect of diagnostic neuroradiology, and recognition of unique features can aid timely diagnosis and treatment.

The role of cellular prion protein in immune system.

Numerous studies have investigated the cellular prion protein (PrPC) since its discovery. These investigations have explained that its structure is predominantly composed of alpha helices and short beta sheet segments, and when its abnormal scrapie isoform (PrPSc) is infected, PrPSc transforms the PrPC, leading to prion diseases, including Creutzfeldt-Jakob disease in humans and bovine spongiform encephalopathy in cattle. Given its ubiquitous distribution across a variety of cellular types, the PrPC manifests a diverse range of biological functions, including cell-cell adhesion, neuroprotection, signalings, and oxidative stress response. PrPC is also expressed in immune tissues, and its functions in these tissues include the activation of immune cells and the formation of secondary lymphoid tissues, such as the spleen and lymph nodes. Moreover, high expression of PrPC in immune cells plays a crucial role in the pathogenesis of prion diseases. In addition, it affects inflammation and the development and progression of cancer via various mechanisms. In this review, we discuss the studies on the role of PrPC from various immunological perspectives. [BMB Reports 2023; 56(12): 645-650].

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.

First Report of the Potential Bovine Spongiform Encephalopathy (BSE)-Related Somatic Mutation E211K of the Prion Protein Gene (PRNP) in Cattle.

Bovine spongiform encephalopathy (BSE) is a prion disease characterized by spongiform degeneration and astrocytosis in the brain. Unlike classical BSE, which is caused by prion-disease-contaminated meat and bone meal, the cause of atypical BSE has not been determined. Since previous studies have reported that the somatic mutation in the human prion protein gene (PRNP) has been linked to human prion disease, the somatic mutation of the PRNP gene was presumed to be one cause of prion disease. However, to the best of our knowledge, the somatic mutation of this gene in cattle has not been investigated to date. We investigated somatic mutations in a total of 58 samples, including peripheral blood; brain tissue including the medulla oblongata, cerebellum, cortex, and thalamus; and skin tissue in 20 individuals from each breed using pyrosequencing. In addition, we estimated the deleterious effect of the K211 somatic mutation on bovine prion protein by in silico evaluation tools, including PolyPhen-2 and PANTHER. We found a high rate of K211 somatic mutations of the bovine PRNP gene in the medulla oblongata of three Holsteins (10% ± 4.4%, 28% ± 2%, and 19.55% ± 3.1%). In addition, in silico programs showed that the K211 somatic mutation was damaging. To the best of our knowledge, this study is the first to investigate K211 somatic mutations of the bovine PRNP gene that are associated with potential BSE progression.

Diffuse Leptomeningeal Oligodendrogliomatosis in a Cow.

A 4.5-year-old cow showing neurological signs consistent with predictors of bovine spongiform encephalopathy (BSE) was investigated as a potential BSE-suspect case and proved to be negative. Macroscopic analysis revealed a tan neoplastic mass growing along the leptomeninges of the caudal brain and extending into the third (III) ventricle without significantly involving the neuroparenchyma. Pathological features (uniform round hyperchromatic neoplastic cells embedded in abundant myxoid matrix, microcysts, microvascular proliferation) and diffuse Olig2 expression were most consistent with diffuse high-grade leptomeningeal oligodendrogliomatosis. In line with former reports of extensive leptomeningeal involvement in bovine oligodendroglioma, this report suggests that bovine oligodendroglial tumors have a strong propensity to grow within the leptomeningeal space. In addition, it indicates that Olig2 is a useful marker to confirm glial lineage in formalin-fixed, paraffin-embedded bovine tissue.

Prion-related peripheral neuropathy in sporadic Creutzfeldt-Jakob disease.

OBJECTIVE: To assess whether the involvement of the peripheral nervous system (PNS) belongs to the phenotypic spectrum of sporadic Creutzfeldt-Jakob disease (sCJD). METHODS: We examined medical records of 117 sCJDVV2 (ataxic type), 65 sCJDMV2K (kuru-plaque type) and 121 sCJDMM(V)1 (myoclonic type) subjects for clinical symptoms, objective signs and neurophysiological data. We reviewed two diagnostic nerve biopsies and looked for abnormal prion protein (PrPSc) by western blotting and real-time quaking-induced conversion (RT-QuIC) in postmortem PNS samples from 14 subjects. RESULTS: Seventy-five (41.2%) VV2-MV2K patients, but only 11 (9.1%) MM(V)1, had symptoms or signs suggestive of PNS involvement occurring at onset in 18 cases (17 VV2-MV2K, 9.3%; and 1 MM(V)1, 0.8%) and isolated in 6. Nerve biopsy showed a mixed predominantly axonal and demyelinating neuropathy in two sCJDMV2K. Electromyography showed signs of neuropathy in half of the examined VV2-MV2K patients. Prion RT-QuIC was positive in all CJD PNS samples, whereas western blotting detected PrPSc in the sciatic nerve in one VV2 and one MV2K. CONCLUSIONS: Peripheral neuropathy, likely related to PrPSc deposition, belongs to the phenotypic spectrum of sCJDMV2K and VV2 and may mark the clinical onset. The significantly lower prevalence of PNS involvement in typical sCJDMM(V)1 suggests that the PNS tropism of sCJD prions is strain dependent.

Caracterización del riesgo de ingreso de encefalopatía espongiforme bovina a El Salvador mediante la importación de especies rumiantes y sus productos durante el periodo 2005-2015 / Characterization of the risk of ingress of bovine spongiform encephalopathy to El Salvador through the importation of ruminant species and their products during the period 2005-2015

El Salvador ha enfrentado dificultades para dar continuidad al proceso de categorización respecto a la Encefalopatía Espongiforme Bovina (EEB) ante la OIE, debido en parte a la deficiencia en la recopilación y ordenamiento de la información relativa a las importaciones de productos, subproductos y animales en pie por lo que la estimación y caracterización del riesgo de introducción de la enfermedad es mucho más difícil de realizar. En el presente trabajo se categorizo el riesgo de ingreso de EEB por las importaciones de origen rumiante, para que El Salvador eventualmente obtenga el reconocimiento sanitario por parte de la OIE para poder comercializar sus bovinos, productos y subproductos, hacia países con la misma condición sanitaria, se realizó una investigación descriptiva observacional, de carácter retrospectiva del periodo de 2005-2015, longitudinal mediante una revisión documental de archivos de las importaciones de productos de origen animal del Ministerio de Agricultura y Ganadería. Se describen un total de 15 países que importaron productos de riesgo en el periodo de 11 años identificando que el país recibe mayor cantidad de productos del área de América Central, teniendo esto poco valor significativo en cuanto al riesgo ya que estos países históricamente no han reportado casos de esta enfermedad. Realizando un cruce de variables de acuerdo al estatus del país de origen se determinó un Riesgo Medio de Introducción de la enfermedad a El Salvador, sin embargo esto representa solamente una parte de la información necesaria para obtener una categorización de País, al mismo tiempo esta investigación contribuye a mejorar los mecanismos de obtención, recopilación y clasificación de la información para tener mayor disponibilidad de datos que favorezcan la vigilancia epidemiológica y la toma de decisiones en la aplicación de medidas sanitarias encaminadas a disminuir el riesgo de ingreso de la EEB

Traceability of animal protein byproducts in ruminants by multivariate analysis of isotope ratio mass spectrometry to prevent transmission of prion diseases

Ruminant feed containing animal byproduct proteins (ABPs) is prohibited in many countries due to its risk of transmitting prion diseases (PD). In most cases the entire herd is sacrificed, which causes great harm to the producer countries by preventing their exportation of ruminant derived-products. Methods: We used stable isotope ratio mass spectrometry (IRMS) of carbon (13C/12C) and nitrogen (15N/14N) to trace the animal protein in the blood of 15 buffaloes (Bubalus bubalis) divided into three experimental groups: 1 - received only vegetable protein (VP) during 117 days; 2 - received animal and vegetable protein (AVP); and 3 - received animal and vegetable protein with animal protein subsequently removed (AVPR). Groups 2 and 3 received diets containing 13.7% bovine meat and bone meal (MBM) added to a vegetable diet (from days 21-117 in the AVP group and until day 47 in the AVPR group, when MBM was removed). Results: On the 36th day, differences were detectable in the feeding profile (p <0.01) among the three experimental groups, which remained for a further 49 days (85th day). The AVPR group showed isotopic rate reversibility on the 110th day by presenting values similar to those in the control group (VP) (p> 0.05), indicating that it took 63 days to eliminate MBM in this group. Total atoms exchange (> 95%) of 13C and 15N was observed through incorporation of the diet into the AVP and AVPR groups. Conclusions: IRMS is an accurate and sensitive technique for tracing the feeding profile of ruminants through blood analysis, thus enabling investigation of ABP use. enabling investigation of ABP use.(AU)

Gross and histopathological pitfalls found in the examination of 3338 cattle brains submitted to the BSE surveillance program in Brazil / Ciladas macroscópicas e histopatológicas encontradas no exame de 3338 encéfalos de bovinos submetidos ao programa de vigilância da EEB no Brasil

This study stems from the findings during the gross and histopathological exam of 3,338 cattle brains as part of the bovine spongiform encephalopathy (BSE) active surveillance program of the Brazilian Ministry of Agriculture, Livestock, and Supply from 2001 to 2005. The work was carried out in the Veterinary Pathology Laboratory of the Federal University of Santa Maria which at the time (2001-2007) was the national reference laboratory for the diagnosis of BSE and other transmissible spongiform encephalopathies. Both gross and histopathological aspects are described. Several gross aspects were annotated: anatomic normal structures not commonly recognized (non-lesions), lesions of no clinical significance, postmortem changes and artifacts; all these can amount to important pitfalls that distract the pathologist during the routine gross examination of the central nervous system (CNS). Accordingly, equivalent pitfalls were described in the histological examination. Non-lesions observed were the pineal body, embryo remnants such as the external germinal layer of the cerebellum, subependymal plates, and clusters of neuroblasts in the basal ganglia; or circumventricular structures such as area postrema, subcomisural organ, and melanosis in the leptomeninges and vessel walls. Lesions with little or no clinical importance included age-related changes as lipofuscin, hemosiderin, mineralization and hyalinization of vessel walls within the brain and meninges. Corpora amylacea and corpora arenacea were detected respectively in astrocyte processes and the pineal body. Cytoplasmic neuronal vacuolization was observed in the red nucleus and habenular nucleus. Sarcocystis sp. without a correspondent inflammatory reaction was rarely observed. Included within findings with no clinical manifestation were axonal spheroids and perivascular mononuclear cuffings. Changes in the CNS due to killing, sampling and fixation methods can obscure or distract from the more critical lesions. The ones related to the process of killing included hemorrhages caused in cattle destroyed by a captive bolt. Artifacts related to sampling and handling of CNS tissue consisted of inclusion of bone sand in the neural tissue from sawing the calvarium; dark neurons produced by excessive handling of the brain, and micro-organisms that contaminated the tissues during sampling or histological processing. Postmortem autolytic or putrefactive changes observed included vacuolar changes in the myelin sheath, clear halos surrounding neurons and oligodendrocytes, clusters of putrefaction bacilli within vessels or dispersed throughout the brain tissue associated or not to clear halos. One interesting, and somewhat frequent, postmortem autolytic change found in the bovine brain was the partial dissolution of the granule cell layer (GCL) of the cerebellum, also referred to as conglutination of the GCL or as the French denomination "état glace". Due to the shortage of comprehensive publications in the subject, this review is intended to address the main pitfalls that can be observed in the brain of cattle hoping to help other pathologists avoiding misinterpret them.(AU)

Os resultados deste estudo foram obtidos pelo exame macroscópico e histopatológico de 3.338 cérebros de bovinos examinados durante o programa de vigilância ativa da encefalopatia espongiforme bovina (BSE) do Ministério da Agricultura, Pecuária e Abastecimento (MAPA), de 2001 a 2005. O trabalho foi realizado no Laboratório de Patologia Veterinária (LPV) da Universidade Federal de Santa Maria (UFSM) que, de 2001 a 2007, foi o laboratório nacional de referência para o diagnóstico da BSE e de outras encefalopatias espongiformes transmissíveis. Macroscopicamente, foram descritas estruturas anatômicas normais (não-lesões), mas que são, com frequência, interpretadas como lesões; lesões sem significado clínico; alterações pós-mortais e artefatos. Esses achados podem confundir e desviar a atenção do patologista durante o exame de rotina do sistema nervoso central (SNC). Da mesma forma, estruturas equivalentes foram descritas no exame histológico. As não-lesões observadas foram corpo pineal, remanescentes embrionários, como a camada germinativa externa do cerebelo, placas subependimárias e aglomerados de neuroblastos nos gânglios da base; ou estruturas circunventriculares, como área de postrema, órgão subcomissural e melanose em leptomeninges e paredes dos vasos. Lesões com pouca ou nenhuma importância relacionadas ao envelhecimento incluíram lipofuscina, hemossiderina, mineralização, hialinização das paredes dos vasos do encéfalo e das meninges. Corpora amylacea foram detectados em processos astrocíticos e corpora arenacea, no corpo pineal. Adicionalmente, foi observada vacuolização no citoplasma de neurônios do núcleo vermelho e do núcleo habenular. Sarcocystis sp. sem reação inflamatória correspondente foi raramente observado. Incluídos nos achados sem manifestação clínica estavam esferóides axonais e manguitos mononucleares perivasculares. Alterações no SNC causadas pelo método de abate, amostragem e fixação podem simular ou obscurecer lesões mais importantes. Aquelas relacionadas ao método de abate incluíram hemorragias causadas em bovinos dessensibilizados pelo dardo cativo ou por punção por faca da medula na articulação atlanto-occipital. Artefatos relacionados à amostragem e manuseio de tecido do SNC consistiram na inclusão de pó de osso no tecido neural em consequência do uso de serra para abrir a caixa craniana; neurônios escuros produzidos pelo manuseio excessivo do cérebro e micro-organismos que contaminaram os tecidos durante a amostragem ou processamento histológico. Alterações autolíticas pós-mortais ou de putrefação incluíram vacuolizações na bainha de mielina, halos claros em torno dos neurônios e oligodendrócitos, aglomerados de bacilos de putrefação dentro dos vasos ou dispersos em todo o tecido cerebral, relacionados ou não a halos claros. Uma alteração autolítica pós-mortal intrigante e relativamente frequente encontrada foi a dissolução parcial da camada de células granulares (CCG) do cerebelo, também referida como conglutinação da CCG ou "état glacé". Devido à escassez de publicações abrangentes neste assunto, esta revisão pretende abordar as principais ciladas que possam aparecer no cérebro de bovinos, na esperança de ajudar outros patologistas a evitar interpretá-las erroneamente.(AU)

Variant Creutzfeldt-Jakob disease.

Variant CJD (vCJD) was described first in the United Kingdom in 1996. It is a zoonotic form of human prion disease, originating from dietary contamination of human food with material from bovine spongiform encephalopathy (BSE)-affected cattle. It has important epidemiologic, clinical, and neuropathogic differences from other forms of human prion disease. Cases have occurred in several countries but the United Kingdom and France have been most affected. Following the decline in BSE in cattle and the dietary protective measures adopted, vCJD has become an extremely rare disease. However, important concerns remain about asymptomatic infection in human populations (especially the United Kingdom) and the possibility of human-to-human transmission via medical and surgical interventions. Definitive diagnosis depends on neuropathology, usually undertaken at autopsy, but sometimes on brain biopsy. Clinical diagnosis with a reasonable degree of likelihood is, however, possible based on the clinical features and the finding of the pulvinar sign on cerebral magnetic resonance. There are also emerging tests (including blood tests) that have promising sensitivity and specificity for vCJD. It is a progressive illness, inevitably fatal with no curative treatment.

Prion Disease in Dromedary Camels, Algeria.

Prions cause fatal and transmissible neurodegenerative diseases, including Creutzfeldt-Jakob disease in humans, scrapie in small ruminants, and bovine spongiform encephalopathy (BSE). After the BSE epidemic, and the associated human infections, began in 1996 in the United Kingdom, general concerns have been raised about animal prions. We detected a prion disease in dromedary camels (Camelus dromedarius) in Algeria. Symptoms suggesting prion disease occurred in 3.1% of dromedaries brought for slaughter to the Ouargla abattoir in 2015-2016. We confirmed diagnosis by detecting pathognomonic neurodegeneration and disease-specific prion protein (PrPSc) in brain tissues from 3 symptomatic animals. Prion detection in lymphoid tissues is suggestive of the infectious nature of the disease. PrPSc biochemical characterization showed differences with BSE and scrapie. Our identification of this prion disease in a geographically widespread livestock species requires urgent enforcement of surveillance and assessment of the potential risks to human and animal health.

Cerebellar compartmentation of prion pathogenesis.

In prion diseases, the brain lesion profile is influenced by the prion "strain" properties, the invasion route to the brain, and still unknown host cell-specific parameters. To gain insight into those endogenous factors, we analyzed the histopathological alterations induced by distinct prion strains in the mouse cerebellum. We show that 22L and ME7 scrapie prion proteins (PrP22L , PrPME7 ), but not bovine spongiform encephalopathy PrP6PB1 , accumulate in a reproducible parasagittal banding pattern in the cerebellar cortex of infected mice. Such banding pattern of PrP22L aggregation did not depend on the neuroinvasion route, but coincided with the parasagittal compartmentation of the cerebellum mostly defined by the expression of zebrins, such as aldolase C and the excitatory amino acid transporter 4, in Purkinje cells. We provide evidence that Purkinje cells display a differential, subtype-specific vulnerability to 22L prions with zebrin-expressing Purkinje cells being more resistant to prion toxicity, while in stripes where PrP22L accumulated most zebrin-deficient Purkinje cells are lost and spongiosis accentuated. In addition, in PrP22L stripes, enhanced reactive astrocyte processes associated with microglia activation support interdependent events between the topographic pattern of Purkinje cell death, reactive gliosis and PrP22L accumulation. Finally, we find that in preclinically-ill mice prion infection promotes at the membrane of astrocytes enveloping Purkinje cell excitatory synapses, upregulation of tumor necrosis factor-α receptor type 1 (TNFR1), a key mediator of the neuroinflammation process. These overall data show that Purkinje cell sensitivity to prion insult is locally restricted by the parasagittal compartmentation of the cerebellum, and that perisynaptic astrocytes may contribute to prion pathogenesis through prion-induced TNFR1 upregulation.

Oral Prion Disease Pathogenesis Is Impeded in the Specific Absence of CXCR5-Expressing Dendritic Cells.

After oral exposure, the early replication of certain prion strains upon stromal cell-derived follicular dendritic cells (FDC) in the Peyer's patches in the small intestine is essential for the efficient spread of disease to the brain. However, little is known of how prions are initially conveyed from the gut lumen to establish infection on FDC. Our previous data suggest that mononuclear phagocytes such as CD11c+ conventional dendritic cells play an important role in the initial propagation of prions from the gut lumen into Peyer's patches. However, whether these cells conveyed orally acquired prions toward FDC within Peyer's patches was not known. The chemokine CXCL13 is expressed by FDC and follicular stromal cells and modulates the homing of CXCR5-expressing cells toward the FDC-containing B cell follicles. Here, novel compound transgenic mice were created in which a CXCR5 deficiency was specifically restricted to CD11c+ cells. These mice were used to determine whether CXCR5-expressing conventional dendritic cells propagate prions toward FDC after oral exposure. Our data show that in the specific absence of CXCR5-expressing conventional dendritic cells the early accumulation of prions upon FDC in Peyer's patches and the spleen was impaired, and disease susceptibility significantly reduced. These data suggest that CXCR5-expressing conventional dendritic cells play an important role in the efficient propagation of orally administered prions toward FDC within Peyer's patches in order to establish host infection.IMPORTANCE Many natural prion diseases are acquired by oral consumption of contaminated food or pasture. Once the prions reach the brain they cause extensive neurodegeneration, which ultimately leads to death. In order for the prions to efficiently spread from the gut to the brain, they first replicate upon follicular dendritic cells within intestinal Peyer's patches. How the prions are first delivered to follicular dendritic cells to establish infection was unknown. Understanding this process is important since treatments which prevent prions from infecting follicular dendritic cells can block their spread to the brain. We created mice in which mobile conventional dendritic cells were unable to migrate toward follicular dendritic cells. In these mice the early accumulation of prions on follicular dendritic cells was impaired and oral prion disease susceptibility was reduced. This suggests that prions exploit conventional dendritic cells to facilitate their initial delivery toward follicular dendritic cells to establish host infection.

Encefalopatia espongiforme bovina atípica: uma revisão / Atypical bovine spongiform encephalopathy: a review

A encefalopatia espongiforme bovina (EEB), causada por um príon infectante, surgiu na década de 1980 na Europa como uma nova doença nos rebanhos bovinos e, desde então, estão sendo tomadas várias ações para sua prevenção e controle. A restrição da alimentação de ruminantes com subprodutos de origem animal e a remoção e destruição dos materiais de risco específico para a doença das carcaças em frigoríficos se mostraram efetivas medidas para o controle da doença, além de reduzirem a exposição humana ao agente, pois se trata de uma importante zoonose. No entanto, em 2004 os primeiros casos atípicos de EEB foram diagnosticados, nos quais os agentes causais apresentavam alterações de peso molecular na prova de Western blot, em relação ao agente da forma clássica. Além das diferenças moleculares dos agentes, as apresentações clínicas mostraram-se diferenciadas nas formas atípicas, acometendo principalmente bovinos com idade superior a oito anos. Por se tratar de uma nova forma da doença, muitos estudos estão sendo conduzidos buscando elucidar a patogenia, epidemiologia e seu potencial zoonótico. Objetivou-se neste estudo revisar os principais aspectos relacionados às EEB atípicas enfatizando sua etiologia, epidemiologia, sinais clínicos, diagnóstico e medidas de controle.(AU)

Bovine spongiform encephalopathy (BSE), caused by an infectious prion, emerged in the 1980s in Europe as a new disease in cattle and, since then, several actions are being taken for its prevention and control. Restricting the feeding of ruminants with animal by-products and the removal and destruction of specific risk materials (SRM) for the condition of carcasses in slaughterhouses have been proven effective to control the disease, in addition to the reduction of human exposure to the agent, as this is an important zoonosis. However, in 2004 the first atypical cases of BSE were diagnosed, in which the causative agents showed different molecular weights in Western blot (WB), compared to the classical form of the agent. In addition to the molecular differences, clinical presentations proved to be differentiated in atypical forms, affecting mainly cattle older than eight years. Because it is a new form of the disease, many studies are being conducted to elucidate the pathogenesis, epidemiology and zoonotic potential of atypical BSE. The aim of this study was to review the main aspects of atypical BSE emphasizing its etiology, epidemiology, clinical signs, diagnosis and control and prevention measures.(AU)

Encefalopatia espongiforme bovina atípica: uma revisão / Atypical bovine spongiform encephalopathy: a review

Bovine spongiform encephalopathy (BSE), caused by an infectious prion, emerged in the 1980s in Europe as a new disease in cattle and, since then, several actions are being taken for its prevention and control. Restricting the feeding of ruminants with animal by-products and the removal and destruction of specific risk materials (SRM) for the condition of carcasses in slaughterhouses have been proven effective to control the disease, in addition to the reduction of human exposure to the agent, as this is an important zoonosis. However, in 2004 the first atypical cases of BSE were diagnosed, in which the causative agents showed different molecular weights in Western blot (WB), compared to the classical form of the agent. In addition to the molecular differences, clinical presentations proved to be differentiated in atypical forms, affecting mainly cattle older than eight years. Because it is a new form of the disease, many studies are being conducted to elucidate the pathogenesis, epidemiology and zoonotic potential of atypical BSE. The aim of this study was to review the main aspects of atypical BSE emphasizing its etiology, epidemiology, clinical signs, diagnosis and control and prevention measures.

A encefalopatia espongiforme bovina (EEB), causada por um príon infectante, surgiu na década de 1980 na Europa como uma nova doença nos rebanhos bovinos e, desde então, estão sendo tomadas várias ações para sua prevenção e controle. A restrição da alimentação de ruminantes com subprodutos de origem animal e a remoção e destruição dos materiais de risco específico para a doença das carcaças em frigoríficos se mostraram efetivas medidas para o controle da doença, além de reduzirem a exposição humana ao agente, pois se trata de uma importante zoonose. No entanto, em 2004 os primeiros casos atípicos de EEB foram diagnosticados, nos quais os agentes causais apresentavam alterações de peso molecular na prova de Western blot, em relação ao agente da forma clássica. Além das diferenças moleculares dos agentes, as apresentações clínicas mostraram-se diferenciadas nas formas atípicas, acometendo principalmente bovinos com idade superior a oito anos. Por se tratar de uma nova forma da doença, muitos estudos estão sendo conduzidos buscando elucidar a patogenia, epidemiologia e seu potencial zoonótico. Objetivou-se neste estudo revisar os principais aspectos relacionados às EEB atípicas enfatizando sua etiologia, epidemiologia, sinais clínicos, diagnóstico e medidas de controle.

Polymorphisms in the Prion Protein Gene of cattle breeds from Brazil / Polimorfismos no gene da proteína priônica em bovinos no Brasil

One of the alterations that occur in the PRNP gene in bovines is the insertion/deletion (indel) of base sequences in specific regions, such as indels of 12-base pairs (bp) in intron 1 and of 23- bp in the promoter region. The deletion allele of 23 bp is associated with susceptibility to bovine spongiform encephalopathy (BSE) as well as the presence of the deletion allele of 12 bp. In the present study, the variability of nucleotides in the promoter region and intron 1 of the PRNP gene was genotyped for the Angus, Canchim, Nellore and Simmental bovine breeds to identify the genotype profiles of resistance and/or susceptibility to BSE in each animal. Genomic DNA was extracted for amplification of the target regions of the PRNP gene using polymerase chain reaction (PCR) and specific primers. The PCR products were submitted to electrophoresis in agarose gel 3% and sequencing for genotyping. With the exception of the Angus breed, most breeds exhibited a higher frequency of deletion alleles for 12 bp and 23 bp in comparison to their respective insertion alleles for both regions. These results represent an important contribution to understanding the formation process of the Brazilian herd in relation to bovine PRNP gene polymorphisms.(AU)

Uma das mudanças que ocorrem no gene PRNP em bovinos é a inserção e/ou deleção (indels) de sequências de bases, em determinadas regiões como, por exemplo, as indels de 12 pares de bases (pb) no íntron 1 e 23pb na região promotora. O alelo de deleção de 23pb está relacionado com a suscetibilidade à Encefalopatia Espongiforme Bovina (EEB), assim como a presença do alelo de deleção de 12pb. Neste estudo foi genotipada a variabilidade de nucleotídeos da região promotora e íntron 1 do gene PRNP em bovinos das raças Angus, Canchim, Nelore e Simental, para identificar os perfis genotípicos de resistência e/ou suscetibilidade à EEB de cada animal. Foi realizada a extração de DNA genômico para amplificação das regiões alvo do gene PRNP, por meio da reação em cadeia de polimerase (PCR) utilizando-se primers específicos. Os produtos da PCR foram submetidos à eletroforese em gel de agarose a 3%, e sequenciamento para a realização da genotipagem. Com exceção da raça Angus, a maioria das raças apresentaram maiores frequências do alelo de deleção tanto para 12pb como 23pb, em comparação com seus respectivos alelos de inserção, para as duas regiões. Esses resultados abrem caminhos para o conhecimento de como o rebanho brasileiro está sendo formado com relação aos polimorfismos do gene PRNP bovino.(AU)

Identification of Proteins and Peptide Biomarkers for Detecting Banned Processed Animal Proteins (PAPs) in Meat and Bone Meal by Mass Spectrometry.

The outbreak of bovine spongiform encephalopathy (BSE) in the United Kingdom in 1986, with processed animal proteins (PAPs) as the main vector of the disease, has led to their prohibition in feed. The progressive release of the feed ban required the development of new analytical methods to determine the exact origin of PAPs from meat and bone meal. We set up a promising MS-based method to determine the species and the source (legal or not) present in PAPs: a TCA-acetone protein extraction followed by a cleanup step, an in-solution tryptic digestion of 5 h (with a 1:20 protein/trypsin ratio), and mass spectrometry analyses, first without any a priori, with a Q-TOF, followed by a targeted triple-quadrupole analysis. Using this procedure, we were able to overcome some of the major limitations of the official methods to analyze PAPs, detecting and identifying prohibited animal products in feedstuffs by the monitoring of peptides specific for cows, pigs, and sheep in PAPs.

BSE-associated prion-amyloid cardiomyopathy in primates.

Prion amyloidosis occurred in the heart of 1 of 3 macaques intraperitoneally inoculated with bovine spongiform encephalopathy prions. This macaque had a remarkably long duration of disease and signs of cardiac distress. Variant Creutzfeldt-Jakob disease, caused by transmission of bovine spongiform encephalopathy to humans, may manifest with cardiac symptoms from prion-amyloid cardiomyopathy.

Spontaneous obesity-linked type 2 diabetes in the absence of islet amyloid in a cynomolgus monkey infected with bovine spongiform encephalopathy.

A 9-year-old cynomolgus monkey (Macaca fascicularis) infected orally with bovine spongiform encephalopathy (BSE) was presented for necropsy following euthanasia 4 years post infection (p.i.). This macaque R984 was exposed to a BSE dose that causes a simian form of variant Creutzfeldt-Jakob disease (vCJD) within 5 years p.i. in other macaques. All orally BSE-infected macaques developed a significant weight gain within the first 2 years p.i. compared with non-BSE-infected age- and sex-matched control animals, suggesting increased risk of type 2 diabetes (T2D). In contrast, macaque R984 developed rapid weight loss, hyperglycemia, and glucosuria and had to be euthanatized 4 years p.i. before clinical signs of vCJD. Pancreas histopathological evaluation revealed severe islet degeneration but, remarkably, no islet amyloid deposits were present. Immunostaining of pancreas sections for insulin and glucagon confirmed the loss of endocrine cells. In addition, prions were present in the adenohypophysis but not in other areas of the brain, indicating centripetal prion spread from the gut during the preclinical phase of BSE infection. Plasma glucose and insulin concentrations of macaque R984 became abnormal with age and resembled T2D. This unusual case of spontaneous T2D in the absence of islet amyloid deposits could have been due to early prion spread from the periphery to the endocrine system or could have occurred spontaneously.