Distinct origins of dura mater graft-associated Creutzfeldt-Jakob disease: past and future problems

Dura mater graft-associated Creutzfeldt-Jakob disease (dCJD) can be divided into two subgroups that exhibit distinct clinical and neuropathological features, with the majority represented by a non-plaque-type of dCJD (np-dCJD) and the minority by a plaque-type of dCJD (p-dCJD). The two distinct phenotypes of dCJD had been considered to be unrelated to the genotype (methionine, M or valine, V) at polymorphic codon 129 of the PRNP gene or type (type 1 or type 2) of abnormal isoform of prion protein (PrP(Sc)) in the brain, while these are major determinants of clinicopathological phenotypes of sporadic CJD (sCJD). The reason for the existence of two distinct subgroups in dCJD had remained elusive. Recent progress in research of the pathogenesis of dCJD has revealed that two distinct subgroups of dCJD are caused by infection with different PrP(Sc) strains from sCJD, i.e., np-dCJD caused by infection with sCJD-MM1/MV1, and p-dCJD caused by infection with sCJD-VV2 or -MV2. These studies have also revealed previously unrecognized problems as follows: (i) the numbers of p-dCJD patients may increase in the future, (ii) the potential risks of secondary infection from dCJD, particularly from p-dCJD, may be considerable, and (iii) the effectiveness of the current PrP(Sc) decontamination procedures against the PrP(Sc) from p-dCJD is uncertain. To prevent secondary infection from p-dCJD, the establishment of effective decontamination procedures is an urgent issue. In this review, we summarize the past and future problems surrounding dCJD

Experimental H-type bovine spongiform encephalopathy characterized by plaques and glial- and stellate-type prion protein deposits

Atypical bovine spongiform encephalopathy (BSE) has recently been identified in Europe, North America, and Japan. It is classified as H-type and L-type BSE according to the molecular mass of the disease-associated prion protein (PrPSc). To investigate the topographical distribution and deposition patterns of immunolabeled PrPSc, H-type BSE isolate was inoculated intracerebrally into cattle. H-type BSE was successfully transmitted to 3 calves, with incubation periods between 500 and 600 days. Moderate to severe spongiform changes were detected in the cerebral and cerebellar cortices, basal ganglia, thalamus, and brainstem. H-type BSE was characterized by the presence of PrP-immunopositive amyloid plaques in the white matter of the cerebrum, basal ganglia, and thalamus. Moreover, intraglial-type immunolabeled PrPSc was prominent throughout the brain. Stellate-type immunolabeled PrPSc was conspicuous in the gray matter of the cerebral cortex, basal ganglia, and thalamus, but not in the brainstem. In addition, PrPSc accumulation was detected in the peripheral nervous tissues, such as trigeminal ganglia, dorsal root ganglia, optic nerve, retina, and neurohypophysis. Cattle are susceptible to H-type BSE with a shorter incubation period, showing distinct and distinguishable phenotypes of PrPSc accumulation

Intraspecies Prion Transmission Results in Selection of Sheep Scrapie Strains

Background: Sheep scrapie is caused by multiple prion strains, which have been classified on the basis of their biological characteristics in inbred mice. The heterogeneity of natural scrapie prions in individual sheep and in sheep flocks has not been clearly defined. Methodology/Principal Findings: In this study, we intravenously injected 2 sheep (Suffolk and Corriedale) with material from a natural case of sheep scrapie (Suffolk breed). These 3 sheep had identical prion protein (PrP) genotypes. The protease-resistant core of PrP (PrPres) in the experimental Suffolk sheep was similar to that in the original Suffolk sheep. In contrast, PrPres in the Corriedale sheep differed from the original PrPres but resembled the unusual scrapie isolate, CH1641. This unusual PrPres was not detected in the original sheep. The PrPres distributions in the brain and peripheral tissues differed between the 2 breeds of challenged sheep. A transmission study in wild-type and TgBoPrP mice, which overexpressing bovine PrP, led to the selection of different prion strains. The pathological features of prion diseases are thought to depend on the dominantly propagated strain. Conclusions/Significance: Our results indicate that prion strain selection occurs after both inter- and intraspecie

Sulfated Dextrans Enhance In Vitro Amplification of Bovine Spongiform Encephalopathy PrPSc and Enable Ultrasensitive Detection of Bovine PrPSc

Prions, infectious agents associated with prion diseases such as Creutzfeldt-Jakob disease in humans, bovine spongiform encephalopathy (BSE) in cattle, and scrapie in sheep and goats, are primarily comprised of PrP(Sc), a protease-resistant misfolded isoform of the cellular prion protein PrP(C). Protein misfolding cyclic amplification (PMCA) is a highly sensitive technique used to detect minute amounts of scrapie PrP(Sc). However, the current PMCA technique has been unsuccessful in achieving good amplification in cattle. The detailed distribution of PrP(Sc) in BSE-affected cattle therefore remains unknown.We report here that PrP(Sc) derived from BSE-affected cattle can be amplified ultra-efficiently by PMCA in the presence of sulfated dextran compounds. This method is capable of amplifying very small amounts of PrP(Sc) from the saliva, palatine tonsils, lymph nodes, ileocecal region, and muscular tissues of BSE-affected cattle. Individual differences in the distribution of PrP(Sc) in spleen and cerebrospinal fluid samples were observed in terminal-stage animals. However, the presence of PrP(Sc) in blood was not substantiated in the BSE-affected cattle examined.The distribution of PrP(Sc) is not restricted to the nervous system and can spread to peripheral tissues in the terminal disease stage. The finding that PrP(Sc) could be amplified in the saliva of an asymptomatic animal suggests a potential usefulness of this technique for BSE diagnosis. This highly sensitive method also has other practical applications, including safety evaluation or safety assurance of products and byproducts manufactured from bovine source materials

Two distinct prions in fatal familial insomnia and its sporadic form

Abstract Fatal familial insomnia is a genetic prion disease, which is associated with the aspartic acid to asparagine substitution at codon 178 of the prion protein gene. Although the hallmark pathological feature is thalamic and olivary degeneration, there is a patient with an atypical fatal familial insomnia without the hallmark feature. The cause of the pathological variability is unclear. We analysed a Japanese fatal familial insomnia kindred and compared one atypical clinicopathological fatal familial insomnia phenotype case and typical fatal familial insomnia phenotype cases with transmission studies using multiple lines of knock-in mice and with protein misfolding cyclic amplification. We also analysed the transmissibility and the amplification properties of sporadic fatal insomnia. Transmission studies revealed that the typical fatal familial insomnia with thalamic and olivary degeneration showed successful transmission only using knock-in mice expressing human–mouse chimeric prion protein gene. The atypical fatal familial insomnia with spongiform changes showed successful transmission only using knock-in mice expressing bank vole prion protein gene. Two sporadic fatal insomnia cases with thalamic and olivary degeneration showed the same transmissibility as the typical fatal familial insomnia phenotype. Interestingly, one sporadic fatal insomnia case with thalamic/olivary degeneration and spongiform changes showed transmissibility of both the typical and atypical fatal familial insomnia phenotypes. Protein misfolding cyclic amplification could amplify both typical fatal familial insomnia cases and sporadic fatal insomnia cases but not the atypical fatal familial insomnia phenotype or other sporadic Creutzfeldt–Jakob disease subtypes. In addition to clinical findings and neuropathological features, the transmission properties and the amplification properties were different between the typical and atypical fatal familial insomnia phenotypes. It is suggested that two distinct prions were associated with the diversity in the fatal familial insomnia phenotype, and these two prions could also be detected in sporadic fatal insomnia

Accumulation of L-type Bovine Prions in Peripheral Nerve Tissues

We recently reported the intraspecies transmission of L-type atypical bovine spongiform encephalopathy (BSE). To clarify the peripheral pathogenesis of L-type BSE, we studied prion distribution in nerve and lymphoid tissues obtained from experimentally challenged cattle. As with classical BSE prions, L-type BSE prions accumulated in central and peripheral nerve tissues

Isolation of two distinct prion strains from a scrapie-affected sheep

We performed a transmission study using mice to clarify the characteristics of the most recent case of scrapie in Japan. The mice that were inoculated with the brain homogenate from a scrapie-affected sheep developed progressive neurological disease, and one of the scrapie-affected mice showed unique clinical signs during primary transmission. This mouse developed obesity, polydipsia, and polyuria. In contrast, the other affected mice exhibited weight loss and hypokinesia. In subsequent passages, the mice showed distinct characteristic scrapie phenotypes. This finding may prove that different prion strains coexist in a naturally affected sheep with scrapie

Anti-Prion Activity of Brilliant Blue G

BACKGROUND: Prion diseases are fatal neurodegenerative disorders with no effective therapy currently available. Accumulating evidence has implicated over-activation of P2X7 ionotropic purinergic receptor (P2X7R) in the progression of neuronal loss in several neurodegenerative diseases. This has led to the speculation that simultaneous blockade of this receptor and prion replication can be an effective therapeutic strategy for prion diseases. We have focused on Brilliant Blue G (BBG), a well-known P2X7R antagonist, possessing a chemical structure expected to confer anti-prion activity and examined its inhibitory effect on the accumulation of pathogenic isoforms of prion protein (PrPres) in a cellular and a mouse model of prion disease in order to determine its therapeutic potential. PRINCIPAL FINDINGS: BBG prevented PrPres accumulation in infected MG20 microglial and N2a neural cells at 50% inhibitory concentrations of 14.6 and 3.2 µM, respectively. Administration of BBG in vivo also reduced PrPres accumulation in the brains of mice with prion disease. However, it did not appear to alleviate the disease progression compared to the vehicle-treated controls, implying a complex role of P2X7R on the neuronal degeneration in prion diseases. SIGNIFICANCE: These results provide novel insights into the pathophysiology of prion diseases and have important implications for the treatment

Neuropathological and biochemical criteria to identify acquired Creutzfeldt-Jakob disease among presumed sporadic cases

As an experimental model of acquired Creutzfeldt-Jakob disease (CJD), we performed transmission studies of sporadic CJD using knock-in mice expressing human prion protein (PrP). In this model, the inoculation of the sporadic CJD strain V2 into animals homozygous for methionine at polymorphic codon 129 (129M/M) of the PRNP gene produced quite distinctive neuropathological and biochemical features, that is, widespread kuru plaques and intermediate type abnormal PrP (PrPSc). Interestingly, this distinctive combination of molecular and pathological features has been, to date, observed in acquired CJD but not in sporadic CJD. Assuming that these distinctive phenotypic traits are specific for acquired CJD, we revisited the literature and found two cases showing widespread kuru plaques despite the 129M/M genotype, in a neurosurgeon and in a patient with a medical history of neurosurgery without dura mater grafting. By Western blot analysis of brain homogenates, we revealed the intermediate type of PrPSc in both cases. Furthermore, transmission properties of brain extracts from these two cases were indistinguishable from those of a subgroup of dura mater graft-associated iatrogenic CJD caused by infection with the sporadic CJD strain V2. These data strongly suggest that the two atypical CJD cases, previously thought to represent sporadic CJD, very likely acquired the disease through exposure to prion-contaminated brain tissues. Thus, we propose that the distinctive combination of 129M/M genotype, kuru plaques, and intermediate type PrPSc, represents a reliable criterion for the identification of acquired CJD cases among presumed sporadic cases