Enfermedad por priones, encefalopatía espongiforme humana y enfermedad de Creutzfeldt-Jakob / Prion induced spongiform encephalopathy of Creutzfeldt-Jakob disease

The infectious protein or prion (PrPSC) is a transmissible and replicable polypeptide, which arises from an abnormal folding of the PrP protein, by unknown mechanisms and without changes in the primary sequence of its amino acids. Its new spatial disposition arises from the substitution of its alpha helices by beta bands, which increase its structural stability, avoiding its complete proteolysis, resulting in a residual accumulation of prions. These prions induce the misfolding of normal PrP protein, generating their exponential increase, leading to a disturbance of neuronal homeostasis which results in the development of the fatal spongiform encephalopathy of the Creutzfeldt-Jakob disease (CJD). This is the most prevalent human prion disease, and 90% of cases are sporadic, suggesting the endogenous genesis of prions. There are different types of prions, identified based on the genetic variance of codon 129 amino acids of the prion protein. Meteonin (M) and Valine (V)), associated with the result of their enzymatic proteolysis, define prions type 1 (21 kDa) and type 2 (19 kDa). The Classical form of CJD produced by MM1 prion occurs in 70% of the cases. The Cerebellar form originated by the VV2 prion occurs in 15% of cases, the form with Kuru plates, associated with the prion MV2 occurs in 5%, and the Vacuolar, related to the MM2 prion occurs in 4%. CJD is always characterized by behavioral, motor, cognitive, and vision alterations and by findings in magnetic resonance imaging, electroencephalogram and cerebrospinal fluid that define each clinical and neuropathological form.

CWD in Norway

The Norwegian Food Safety Authority (NFSA) and Norwegian Environmental Authority (NEA) asked the Norwegian Scientific Committee for Food Safety (Vitenskapskomiteen for mattrygghet, VKM) for an opinion on factors associated with the introduction of Chronic Wasting Disease (CWD) to Norway. VKM appointed a working group consisting of two members of the Panel on Biological Hazards, one member of Panel on Animal Health and Welfare, and two external experts to prepare the answer to the questions. The Panel on Biological Hazards has reviewed and revised the draft prepared by the working group and approved the opinion. CWD was diagnosed in March 2016 in a wild reindeer (Rangifer tarandus) from the Nordfjella mountain area in Norway and in May and June in two mooses (Alces alces) in Selbu in South Trøndelag County, approximately 300 km north from the first case. There is currently no information to determine the origin(s) of CWD agents in Norway. However, the sporadic or genetic (somatic mutation) occurrence of prion disease in cervids cannot be excluded, nor can introduction from North America or other countries. Furthermore, there is no evidence that it has not been circulating at low levels in the Norwegian cervid populations for years, but has not previously been identified. In this scientific opinion, information on prion diseases in general, and CWD in particular, is presented in the light of experiences with this disease in North America. Prions are among the most resilient pathogens known and dissemination of prions into ecosystems is likely to result in long-term problems. Prions bind strongly to soil and remain infectious. In CWD, prions are present in most peripheral organs and also shed into the environment via saliva, faeces, and urine, as well as with the placenta. CWD transmits easily among cervids, either through direct contact, or indirectly via the environment. Migration of animals is relevant for the spread between areas. Strain diversification might occur in CWD and may influence transmission properties of the agents. Clinical signs of CWD are non-specific and do not alone enable confirmation of the diagnosis. Analysis of tissue from the brainstem at the level of the obex by approved methods is necessary for diagnosis of CWD. Prion infectivity is assessed by bioassays, often involving transgenic mice. In vitro conversion assays, like protein misfolding cyclic amplification (PMCA), provide sensitive quantification of converting activity, which is a good approximation of infectivity. Genetic variation (polymorphisms) in the gene that encodes PrP (PRNP) can modulate sensitivity towards CWD. The level of such genetic variation in Norwegian wild and semi-domesticated cervids is currently unknown. Cattle and sheep are at very low risk of developing CWD and it is highly unlikely that prion diseases in sheep or cattle are the origin of CWD. Although transmission of CWD to humans has never been known to occur, and animals other than cervids have not been found to be infected, indicating a species barrier, this possibility cannot be excluded. Thus, measures for reduction of human exposure are recommended. Taking into account uncertainties regarding the plasticity of the CWD agents and the lack of transmission data from the Norwegian isolates, this scientific opinion considers the zoonotic risk of CWD to be very low.

Gerstmann-Sträussler-Scheinker Disease (Pro102Leu) Presenting as Rapidly Progressive Dementia

Genetic prion diseases account for about 10-15% of all cases of human prion disease and are caused by mutations in the prion protein gene. Gerstmann-Sträussler-Scheinker (GSS) disease is a rare genetic prion disease, which is characterized by slowly progressive cerebellar ataxia and the occurrence of cognitive decline in the later stage. P102L is the most common mutation in GSS. We report a patient with a P102L mutation that initially manifested as rapidly progressive dementia without cerebellar symptoms.

Fatal familial insomnia preliminarily diagnosed as frontotemporal dementia: a case report and literature review / 中华神经科杂志

Objective To explore the clinical,imaging,genetic features in a case of fatal familial insomnia (FFI),and review related literatures.Methods A case of middle-aged woman diagnosed as frontotemporal dementia based on the preliminary manifestation of abnormal mental behavior was reported.The clinical features,imaging characteristics,electroencephalogram and polysomnogram of the patient were analyzed,and the blood samples from the patient and some of her familial members were collected for the sequencing of prion protein gene (PRNP).Results This patient was a middle-aged woman,whose clinical manifestations were abnormal mental behavior,rapid progressive dementia and intractable insomnia,abnormal night sleep behavior and laryngeal stridor.Brain MRI indicated frontotemporal lobe atrophy.Non-sleep disturbance was observed in polysomnography.The cerebrospinal fluid was negative for 14-3-3 protein.The results of PRNP sequencing revealed that the mutation of gene D178N/129M was detected.Conclusions Detection of PRNP plays an important role in the diagnosis of FFI.Patients suspected of FFI in clinic should be detected for genetic testing.Whether the frontotemporal lobe atrophy was caused by FFI or concurrent with FFI remains to be further verified.

High phenotypic variability in Gerstmann-Sträussler-Scheinker disease / Elevada variabilidade fenotípica na doença de Gerstmann-Sträussler-Scheinker

ABSTRACT Gerstmann-Sträussler-Scheinker is a genetic prion disease and the most common mutation is p.Pro102Leu. We report clinical, molecular and neuropathological data of seven individuals, belonging to two unrelated Brazilian kindreds, carrying the p.Pro102Leu. Marked differences among patients were observed regarding age at onset, disease duration and clinical presentation. In the first kindred, two patients had rapidly progressive dementia and three exhibited predominantly ataxic phenotypes with variable ages of onset and disease duration. In this family, age at disease onset in the mother and daughter differed by 39 years. In the second kindred, different phenotypes were also reported and earlier ages of onset were associated with 129 heterozygosis. No differences were associated with apoE genotype. In these kindreds, the codon 129 polymorphism could not explain the clinical variability and 129 heterozygosis was associated with earlier disease onset. Neuropathological examination in two patients confirmed the presence of typical plaques and PrPsc immunopositivity.

RESUMO A doença de Gerstmann-Sträussler-Scheinker é uma doença priônica genética, cuja mutação mais frequente é p.Pro102Leu. Descrevem-se dados clínicos, moleculares e neuropatológicos de sete indivíduos em duas famílias não relacionadas com p.Pro102Leu. Diferenças notáveis entre os pacientes em relação à idade de início, duração da doença e apresentação clínica foram encontradas. Na primeira família, dois pacientes apresentaram demência rapidamente progressiva e três apresentaram fenótipo de ataxia com idade variáveis de início e duração da doença. Nesta família, a idade de início entre mãe e filha diferiu em 39 anos. Na segunda família, fenótipos diferentes foram observados e idades precoces de início dos sintomas foram associadas à heterozigose no códon 129. Não houve diferença em relação ao genótipo do gene da apoE. O genótipo do códon 129 não foi responsável pela variabilidade clínica; heterozigose no códon 129 esteve associada ao início precoce da doença. O exame neuropatológico em dois pacientes confirmou presença de placas típicas e imunohistoquímica para PrPsc.

Positive 14-3-3 and tau proteins in a sporadic Creutzfeldt-Jakob disease case and a brief perspective of prion diseases in Colombia / Proteínas 14-3-3 y tau positivas en un caso de enfermedad esporádica de Creutzfeldt-Jakob y una breve reseña de las enfermedades priónicas en Colombia

Prion diseases are rare neurodegenerative disorders occurring worldwide and affecting both humans and animals. Herein, we present the case of a patient diagnosed with definite sporadic Creutzfeldt-Jakob disease in Cali, Colombia. Besides neurological examination, 14-3-3 and tau proteins were valuable tools supporting the diagnosis. We also present a brief perspective of the prion diseases reported in Colombia to date. Although the incidence of prion diseases is unknown in Colombia, our literature review revealed that one case of scrapie in 1981 and 29 human sporadic cases of Creutzfeldt-Jakob disease have been documented and published in our country.

Las enfermedades priónicas son alteraciones neurodegenerativas raras que ocurren en todo el mundo y afectan tanto a humanos como a animales. En el presente artículo, se reporta un caso con diagnóstico confirmado de enfermedad esporádica de Creutzfeldt-Jakob. Además del examen neuropatológico, las proteínas 14-3-3 y tau fueron herramientas valiosas que ayudaron en el diagnóstico. También, se presenta una breve reseña de las enfermedades priónicas reportadas en Colombia hasta la fecha. Aunque en el país se desconoce la incidencia de las enfermedades priónicas, nuestra búsqueda en la literatura científica reveló informes publicados sobre un caso de tembladera de las ovejas ( scrapie o encefalopatía espongiforme ovina) en 1981 y 29 casos esporádicos de Creutzfeldt-Jakob en el país.

Forma esporádica de enfermedad de Creutzfeldt-Jakob: reporte dedos casos / Sporadic Creutzfeldt-Jakob disease: two case reports

La enfermedad de Creutzfeldt-Jakob es la encefalopatía espongiforme más común en el ser humano y prototipode las patologías causadas por priones. Se caracteriza histológicamente por astrogliosis y degeneración dela sustancia gris. Típicamente inicia con síntomas prodrómicos no específicos progresando a demencia conmioclonias y ataxia. Presentamos dos casos de mujeres en edad media con deterioro cognitivo progresivo,dificultades motrices, alteraciones del lenguaje y mioclonias que conducen a la muerte. En electroencefalogramasde ondas trifásicas lentas periódicas así como elevación de proteínas tau y 14-3-3 en LCR por apoyodel The National Prion Disease Pathology Surveillance Center - Cleveland, todos estos hallazgos definen lascondiciones para el diagnóstico clínico de enfermedad por priones. El diagnóstico diferencial en el contextode demencia rápidamente progresiva es amplio, incluyendo infecciones, intoxicaciones, trastornos metabólicos,autoinmunidad, vasculopatías y neoplasias que podrían explicar un posible subregistro en las estadísticasregionales. Existe una posible asociación de riesgo entre enfermedad por priones y médicos patólogos que,aunque discutida, podría limitar el estudio de los especímenes histológicos que son la clave del diagnósticodefinitivo. A pesar de la importancia en salud pública de estas condiciones, el actual modelo de salud limita elmanejo integral de los pacientes.

Creutzfeldt-Jakob is the most common spongiform encephalopathy in humans and the prototype of prions diseases. Astrogliosis and degeneration of the gray matter are the histological features. Typically starts with nonspecific prodromal symptoms that progressing to dementia with myoclonus and ataxia. We present two cases of women in middle age with progressive cognitive impairment, motor difficulties, language disorders and myoclonus that lead to death. EEG slow periodic triphasic waves and elevated protein tau and CSF14-3-3 support for The National Prion Disease Pathology Surveillance Center - Cleveland, all these findings define the conditions for the clinical diagnosis of prion disease. The differential diagnosis in the context of rapidly progressive dementia is broad including infections, poisoning, metabolic disorders, autoimmunity, vascular disease and neoplasms that could explain a possible underreporting in regional statistics. There is a possible risk association between disease and Medical Pathologists that although discussed could limit the study of histological specimens that are key to definitive diagnosis. Despite the public health importance of these conditions the current model of health limits the comprehensive management of patients.

Avaliação epidemiológica dos óbitos por doenças priônicas no Brasil sob o enfoque da biossegurança / Epidemiological evaluation of deaths by prionic diseases in Brazil on the perspective of biosafety

A emergência e a reemergência das doenças infecciosas oferece desafios à saúde pública, gerando demandas para os governos e para a comunidade científica; o que leva à priorização de ações em saúde, estabelecimento de políticas, aprimoramento da vigilância, além da manutenção de uma boa infraestrutura laboratorial e do cumprimento das medidas de biossegurança. As encefalopatias espongiformes transmissíveis são doenças neurodegenerativas, causadas por um agente infeccioso desprovido de material genético, composto por elementos proteicos, altamente estáveis e resistentes aos processos de descontaminação utilizados rotineiramente nos serviços de saúde e assim representam riscos à saúde pública. Este estudo objetivou identificar os óbitos registrados no Brasil causados por príons, para estabelecer medidas de biossegurança relativas aos riscos oferecidos aos profissionais de saúde, no sentido de prevenir doenças ocupacionais. Foram levantados os óbitos por doenças priônicas no Brasil, no período de janeiro de 2005 a dezembro de 2010, utilizando como fonte de obtenção de dados o Sistema de Informações sobre Mortalidade (SIM), do Ministério da Saúde. Foi identificado 1 caso de Kuru e 132 casos de doença de Creutzfeldt-Jakob, do total de 171.223 óbitos causados por doenças infecciosas e parasitárias. Os príons foram classificados quanto ao risco e a seguir foram identificadas as medidas de biossegurança.

The emergence and re-emergence of infectious diseases poses challenges to public health, demanding priority health actions to governments and the scientific community, while improving health surveillance, good laboratory infrastructure and compliance with biosafety measures. Transmissible spongiform encephalopaties are a group of neuro-degenerative infections caused by a "naked" infectious agent, with protein elements in its structure, but without genetic material. They are highly stable agents, resistant to most decontamination processes used routinely on health services, therefore representing a public health hazard. The present study aims at analyzing deaths registered in Brazil caused by prions, and establishing biosafety measures related to risks for the health professionals, in order to prevent occupational diseases. A survey of deaths from prion disease was made in Brazil from January 2005 to December 2010. The Mortality Information System (SIM) of the Brazilian Ministry of Health was used to obtain these data. We identified 1 case of Kuru and 132 cases of Creutzfeldt-Jakob disease of the total 171,223 deaths caused by infectious and parasitic diseases. Prions were classified according to risk and the biosafety measures were identified.

Expression and clinical significance of cellular prion protein in rectal cancer and adenoma / 解放军医学杂志

Objective To determine the expressions of cellular prion protein (PrPC) in normal rectal mucosa, rectal adenoma and rectal carcinoma tissues, and to study the relationship of PrPC with development and progression of rectal carcinoma. Methods Immunohistochemical method (SP method) was used to determine the expressions of PrPC in rectal carcinoma (60 samples), rectal adenoma (20 samples) and normal rectal mucosa (20 samples), and the correlations between the expression of PrPC in rectal carcinoma tissue, and clinical pathological parameters including sex, tumor differentiation, clinical stages, lymph node metastasis, etc. were analyzed. Results PrPC was expressed in normal rectal mucosa, rectal adenoma and rectal carcinoma tissues. The positive rate of PrPC expression in rectal carcinoma (65%) was significantly higher than that in rectal adenoma (35%) and normal rectal mucosa (15%) with statistical significance (PC was closely related with tumor differentiation, TNM stage and lymph node metastasis (P0.05). Conclusion PrPC may play an important role in the process of development, progression and metastasis of rectal carcinoma.

Advances in molecular chaperones regulating yeast prion [ PSI+] propagation / 军事医学

The finding and research on yeast prion are of great values for biology and medical sciences.Research advances in molecular chaperones, especially in Hsp104p, Hsp70p and Hsp40p, regulating yeast prion [PSI+] propaga-tion,are reviewed.

Classical natural ovine scrapie prions detected in practical volumes of blood by lamb and transgenic mouse bioassays

Scrapie is diagnosed antemortem in sheep by detecting misfolded isoforms of prion protein (PrP(Sc)) in lymphoid follicles of the rectal mucosa and nictitating membranes. Assay sensitivity is limited if (a) the biopsy is collected early during disease development, (b) an insufficient number of follicles is collected, or (c) peripheral accumulation of PrP(Sc) is reduced or delayed. A blood test would be convenient for mass live animal scrapie testing. Currently approved techniques, however, have their own detection limits. Novel detection methods may soon offer a non-animal-based, rapid platform with detection sensitivities that rival the prion bioassay. In anticipation, we sought to determine if diseased animals could be routinely identified with a bioassay using B lymphocytes isolated from blood sample volumes commonly collected for diagnostic purposes in small ruminants. Scrapie transmission was detected in five of six recipient lambs intravenously transfused with B lymphocytes isolated from 5~10 mL of blood from a naturally scrapie-infected sheep. Additionally, scrapie transmission was observed in 18 ovinized transgenic Tg338 mice intracerebrally inoculated with B lymphocytes isolated from 5~10 mL of blood from two naturally scrapie-infected sheep. Based on our findings, we anticipate that these blood sample volumes should be of diagnostic value.

Enfermedad de creutzfeldt-jakob en el Perú: reporte de once casos / Creutzfeldt-jakob disease in Peru: report of eleven cases

La enfermedad de Creutzfeldt-Jakob (ECJ) es una enfermedad neurológica fatal producida por la isoforma patológica de la proteína priónica humana. Se reporta las características clínicas de seis casos de la forma esporádica de ECJ con diagnóstico definitivo por histopatología, y cinco casos con diagnóstico probable, en pacientes atendidos en el Instituto Nacional de Ciencias Neurológicas del Perú. La edad de inicio en los casos definitivos fue de 55,8 años y, en los probables, de 59,6 años, con predominio del sexo masculino. El tiempo de enfermedad fue de 8,8 meses. Se encontró un EEG típico en 50% de los casos definitivos y 80% de los probables. La proteína 14-3-3 en líquido cefalorraquídeo fue positiva en un caso probable y los hallazgos típicos en resonancia magnética se observaron en dos casos probables. Todos los casos cursaron con una evolución clínica típica de la enfermedad, y se considera el primer reporte de ECJ en el Perú.

Creutzfeldt-Jakob disease (CJD) is a fatal neurological disease caused by pathological isoform of the human prion protein. Clinical features of six cases of the sporadic form of CJD with definitive diagnosis by histopathology, and five cases with probable diagnosis were reported in patients treated at the Peruvian National Institute of Neurological Sciences. The average age of onset in definite cases was 55.8 years and in probable cases was 59.6, mostly males. The average disease duration was 8.8 months. A typical EEG was found in 50% of definite cases and in 80% of probable. The 14-3-3 protein in cerebrospinal fluid was positive in a probable case, and typical MRI findings were observed in two probable cases. All cases studied had a typical clinical course of the disease, and it is considered as the first report of CJD in Peru.

Enfermedad de Creutzfeldt-Jakob, hallazgos en resonancia magnética. Presentación de un caso / Creutzfeldt-Jakob Disease, MRI Findings: A Case Report

Se presenta el caso de una paciente de 67 años que consultó por un cuadro progresivo de alteraciones neurológicas y deterioro cognitivo, las cuales, el curso de 6 meses, condujeron a su fallecimiento. Con base en los hallazgos de la resonancia magnética cerebral se hizo un diagnóstico presuntivo de enfermedad de Creutzfeldt-Jakob, confirmado por la presencia de proteína 14-3-3 elevada en el líquido cefalorraquídeo. Se explica brevemente la fisiopatología y la clínica de los pacientes con enfermedad de Creutzfeldt-Jakob y se revisan con detalle los cambios que se observan en las imágenes por resonancia magnética.

We present the case of a 67-year-old female patient with progressive neurologic symptoms and cognitive decline, which caused her demise in 6 months. Based on brain MRI findings, a presumptive diagnosis of Creutzfeldt-Jakob disease was established, confirmed by the presence of elevated 14-3-3 protein in spinal fluid. We briefly explain the physiopathology and clinical changes in patients with Creutzfeldt-Jakob disease, and review in detail the imaging findings on brain MRI.

Evaluation of Infective Property of Recombinant Prion Protein Amyloids in Cultured Cells Overexpressing Cellular Prion Protein

Misfolded isoform of prion protein (PrP), termed scrapie PrP (PrP(Sc)), tends to aggregate into various fibril forms. Previously, we reported various conditions that affect aggregation of recombinant PrP into amyloids. Because amyloidogenesis of PrP is closely associated with transmissible spongiform encephalopathies such as Creutzfeldt-Jakob disease in humans, we investigated infectivity of recombinant PrP amyloids generated in vitro. Using cultured cell lines which overexpress cellular PrP of different species, we measured the level of de novo synthesized PrP(Sc) in cells inoculated with recombinant mouse PrP amyloids. While PrP-overexpressing cells were susceptible to mouse-adapted scrapie prions used as the positive control, demonstrating the species barrier effect, infection with amyloids made of truncated recombinant PrP (PrP[89-230]) failed to form and propagate PrP(Sc) even in the cells that express mouse cellular PrP. This suggests that infectivity of PrP amyloids generated in vitro is different from that of natural prions. Recombinant PrP (89-230) amyloids tested in the current study retain no or a minute level, if any, of prion infectivity.

Clinical, histopathological and genetic studies in a case of fatal familial insomnia / 中华神经科杂志

ObjectiveTo explore clinical,histopathological and genetic features in a case of fatal familial insomnia (FFI) and related literatures were reviewed. Methods The clinical features in one patient with FFI were analyzed,and the dead patient was examined at autopsy and histopathological studies were performed on the brain tissues; and the blood samples from the patient and some of her familial members were collected for the sequencing of prion protein gene (PRNP). Results The main clinical features included intractable insomnia,psychiatric symptoms and abnormal night sleep behavior,unsteady gait,difficulty swallowing,sudden death,and positive family history. The pathological studies showed multiple neuronal loss and gliosis of brain tissues from the proband,predominated in thalamus; and analysis of PRNP revealed gene D178N mutation,and linkage with 129 methionine (Met) allele in the proband and a relative.ConclusionsFFI patients may manifest as sudden death,and may have prominent psychiatric symptoms; the corresponding gene mutation could occur in the asymptomatic carriers; the data of autopsy and brain tissue pathology is helpful for further understanding of this disease.

Enfermedades por priones: de la clínica a la biología molecular / Prion diseases: from molecular biology to clinical practice

Las enfermedades ocasionadas por priones son también conocidas como encefalitis espongiformes transmisibles o demencias de tipo infeccioso. En humanos las presentaciones clínicas más reconocidas son la enfermedad de Creutzfeldt-Jakob, el síndrome de Gerstmann-Strãussler-Scheinker y el insomnio fatal familiar. Son consideradas patologías poco comunes, pero los descubrimientos en biología molecular de los últimos años muestran que los mecanismos patológicos que llevan a su desarrollo pueden ser comunes a varias enfermedades neurodegenerativas, lo cual puede ampliar el espectro patológico, convirtiéndolas en alteraciones no tan infrecuentes en neurología. Esta revisión pretende dar herramientas al clínico para reconocer estas enfermedades discutiendo las presentaciones clínicas en seres humanos con sus variantes: esporádicas, infecciosas y familiares, comentando además el uso de laboratorios, criterios diagnósticos y aproximación terapéutica.

Illnesses caused by prions are also known as Transmissible Spongiform Encephalopathies or infectious dementias. The most recognized clinic presentations in humans are the Creutzfeldt-Jakob disease, the Gerstmann-Sträussler-Scheinker syndrome and the Fatal Familial Insomnia. They are considered uncommon pathologies, but discoveriesin molecular biology in recent years, reveal that pathological mechanisms that allow its development could becommon to several neurodegenerative diseases in which the pathologic spectrum can be amplified, becomingnot infrequent neurological diseases. This review gives tools to the clinical attendant in order to recognize thesedisorders, discussing the clinical presentations: sporadic, infectious and familiar, diagnostic work up, diagnosticcriteria and therapeutic approach.

Occupational hazard with “PRIONS”- in Autopsy workers.

Autopsy room as a potential source of infection to Forensic Pathologists / Autopsy Surgeons and other personnel assisting to conduct an autopsy is a well documented fact. Most frequently reported infections are tuberculosis, brucellosis, salmonellosis, HIV, hepatitis viruses (HBV, HCV etc). New worrisome infective agents called ‘PRIONS’ are associated with degenerative diseases of the central nervous system (CNS) in man and animals (e.g. Mad Cow Disease). Prions are proteinaecious infective agents characterized by extreme resistance to conventional inactivation procedures and transmissible through food, contaminated instruments etc.

Comparative bioinformatics analysis of prion proteins isolated from reptile, rodent, ruminant, and human species

Prion proteins (PrPs) are infectious pathogens that cause a group of invariably fatal, neurodegenerative diseases, including Creutzfeldt-Jakob disease, by means of an entirely novel mechanism. They are produced by various species, including reptile, rodent, ruminant and mammals, during normal metabolic processes, but they can be slowly changed into pathogenic isoforms upon contact with other infectious PrP isoforms. This transmission can occur across species barriers. In the present study, phylogram for each PrP sequence was generated by PAUP* 4.0 program using Neighbor-Joining method with 1,000 times bootstrapping process for the phylogenetic analysis. The molecular dynamics (MD) simulations were performed by the SANDER module in the AMBER 7 package using Amber 99 force field. All the simulation process was conducted in the IBM p690 Supercomputing System in Korea Institute of Science and Technology Information. To reduce the calculation time, we used the Generalized Born (GB) model. We compared the sequences and structural characteristics of normal and pathogenic (E200K) human PrPs with those of other reptile, rodent, ruminant and mammalian PrPs. Phylogenetic analysis revealed that, although the turtle PrP sequence is the most distinct of the PrPs analyzed, it nonetheless retains five conserved secondary structural elements that are similar to those found in the mammalian PrPs, suggesting that these elements have important functions in vivo. The RMS deviation between the normal and E200K human PrPs was larger than that between the normal human and bovine PrPs, and all of the beta-sheet structures in human E200K PrP were very stable during MD simulations.

A Chinese genetic prion disease:clinical,pathological manifestation and prion protein gene mutation analysis / 中华神经科杂志

Objective To report a large family with an autosomal dominant dementia associated with mutation in the prion protein gene(PRNP)and the detailed clinical,neuroimaging and pathological manifestations.Methods Two patients from a large family of dementia were admitted to our ward and the data of their medical history,physical examination,video electroenceplialogram,neuroimaging were colleted.A sterotactic biopsy of the right frontal lobe of the proband was done.After the informed consent from the family members obtained,the genomic DNA was extracted from peripheral blood leucocytes of 5 persons followed by in,vitro amplification using polymerase chain reaction(PCR).The PCR products were directly sequenced by Sanger method.PRNP gene sequence was also examined in 150 normal Chinese to exclude single nueleotide polymorphism.Results A missense mutation of PRNP gene in 5 farnily members was detected,resulting in Gll4V mutation in the prion protein,with M/M genotype of eodon 129.This mutation was not detected in 150 normal Chinese.The proband was diagnosed as inherited prion disease by her clinical features,including neuropsychiatrie disturbances and progressive dementia,and manifestations of neuroimaging,EEG,neuropathology and PRNP gene mutation.Conclusion The first autosomal dominant pedigree of family prion disease is found in China with G114V mutation in PRNP gene which may lead to the prion disease directly.

Investigation of prion protein gene in 10 sporadic Creutzfeldt-Jakob disease patients: a new novel mutation of prion protein gene / 中华神经科杂志

Objective To detect point mutations of the PRNP in 10 sporadic Creutzfeldt-Jakob disease (CJD) patients. Methods Priori protein gene open reading frame was amplified by PCR of genomic DNA extracted from peripheral blood leukocytes. Products were sequenced and digested with restriction endonuc lease Nsp I to check the phenotype at codon 129. Results Two CJD patients were confirmed at autopsy. One full sequencing of the PRNP open reading frame revealed normal, but the other revealed a single novel mutation consisting of a cytosine-to-guanine substitution at nucleotide 729, causing asparagine to replace glutamic acid at codon 211. Among 8 probable CJD patients, 2 full sequencing of the PRNP open reading frame revealed anadenine-to-guanine substitution at nucleotide 751, causing lysine to replace glutamic acid at codon 219. The patients were methionine homozygosity at codon 129. Conclusions The E211D mutation was identified in a confirmed CJD patient. The novel point mutation might be associated with familial CJD. However, E219K identified in 2 possible CJD patients was included in polymorphism of the PRNP as well as M129V. Analysis of PRNP plays an important role for diagnose of familial priori disease.