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Bruno R, Riccardi G, Iacobone F, Chiarotti F, Pirisinu L, Vanni I, Marcon S, D'Agostino C, Giovannelli M, Parchi P, Agrimi U, Nonno R, Di Bari MA. Strain-Dependent Morphology of Reactive Astrocytes in Human- and Animal-Vole-Adapted Prions. Biomolecules 2023; 13:biom13050757. [PMID: 37238627 DOI: 10.3390/biom13050757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/21/2023] [Accepted: 04/25/2023] [Indexed: 05/28/2023] Open
Abstract
Reactive astrogliosis is one of the pathological hallmarks of prion diseases. Recent studies highlighted the influence of several factors on the astrocyte phenotype in prion diseases, including the brain region involved, the genotype backgrounds of the host, and the prion strain. Elucidating the influence of prion strains on the astrocyte phenotype may provide crucial insights for developing therapeutic strategies. Here, we investigated the relationship between prion strains and astrocyte phenotype in six human- and animal-vole-adapted strains characterized by distinctive neuropathological features. In particular, we compared astrocyte morphology and astrocyte-associated PrPSc deposition among strains in the same brain region, the mediodorsal thalamic nucleus (MDTN). Astrogliosis was detected to some extent in the MDTN of all analyzed voles. However, we observed variability in the morphological appearance of astrocytes depending on the strain. Astrocytes displayed variability in thickness and length of cellular processes and cellular body size, suggesting strain-specific phenotypes of reactive astrocytes. Remarkably, four out of six strains displayed astrocyte-associated PrPSc deposition, which correlated with the size of astrocytes. Overall, these data show that the heterogeneous reactivity of astrocytes in prion diseases depends at least in part on the infecting prion strains and their specific interaction with astrocytes.
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Affiliation(s)
- Rosalia Bruno
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Geraldina Riccardi
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Floriana Iacobone
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Flavia Chiarotti
- Reference Center for the Behavioral Sciences and Mental Health, Italian National Institute of Health, 00161 Rome, Italy
| | - Laura Pirisinu
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Ilaria Vanni
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Stefano Marcon
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Claudia D'Agostino
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Matteo Giovannelli
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Piero Parchi
- IRCCS Istituto delle Scienze Neurologiche di Bologna, 40139 Bologna, Italy
- Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, 40138 Bologna, Italy
| | - Umberto Agrimi
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Romolo Nonno
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Michele Angelo Di Bari
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
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Arshad H, Patel Z, Amano G, Li LY, Al-Azzawi ZAM, Supattapone S, Schmitt-Ulms G, Watts JC. A single protective polymorphism in the prion protein blocks cross-species prion replication in cultured cells. J Neurochem 2023; 165:230-245. [PMID: 36511154 DOI: 10.1111/jnc.15739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/22/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022]
Abstract
The bank vole (BV) prion protein (PrP) can function as a universal acceptor of prions. However, the molecular details of BVPrP's promiscuity for replicating a diverse range of prion strains remain obscure. To develop a cultured cell paradigm capable of interrogating the unique properties of BVPrP, we generated monoclonal lines of CAD5 cells lacking endogenous PrP but stably expressing either hamster (Ha), mouse (Mo), or BVPrP (M109 or I109 polymorphic variants) and then challenged them with various strains of mouse or hamster prions. Cells expressing BVPrP were susceptible to both mouse and hamster prions, whereas cells expressing MoPrP or HaPrP could only be infected with species-matched prions. Propagation of mouse and hamster prions in cells expressing BVPrP resulted in strain adaptation in several instances, as evidenced by alterations in conformational stability, glycosylation, susceptibility to anti-prion small molecules, and the inability of BVPrP-adapted mouse prion strains to infect cells expressing MoPrP. Interestingly, cells expressing BVPrP containing the G127V prion gene variant, identified in individuals resistant to kuru, were unable to become infected with prions. Moreover, the G127V polymorphic variant impeded the spontaneous aggregation of recombinant BVPrP. These results demonstrate that BVPrP can facilitate cross-species prion replication in cultured cells and that a single amino acid change can override the prion-permissive nature of BVPrP. This cellular paradigm will be useful for dissecting the molecular features of BVPrP that allow it to function as a universal prion acceptor.
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Affiliation(s)
- Hamza Arshad
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Zeel Patel
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
| | - Genki Amano
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
| | - Le Yao Li
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Zaid A M Al-Azzawi
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
| | - Surachai Supattapone
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
- Department of Medicine, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Gerold Schmitt-Ulms
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Joel C Watts
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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3
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Myskiw J, Lamoureux L, Peterson A, Knox D, Jansen GH, Coulthart MB, Booth SA. Development of an Automated Capillary Immunoassay to Detect Prion Glycotypes in Creutzfeldt-Jakob Disease. J Transl Med 2023; 103:100029. [PMID: 36925197 DOI: 10.1016/j.labinv.2022.100029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 09/23/2022] [Accepted: 11/07/2022] [Indexed: 01/11/2023] Open
Abstract
Creutzfeldt-Jakob disease (CJD) comprises a group of transmissible neurodegenerative diseases with vast phenotypic diversity. Sporadic CJD heterogeneity is predominantly influenced by the genotype at codon 129 of the prion-encoding gene and the molecular weight of PrPSc fragments after protease digestion, resulting in a classification of 6 subtypes of CJD (MM1, MM2, MV1, MV2, VV1, and VV2). The majority of cases with CJD can be distinguished using this classification system. However, a number of reported CJD cases are phenotypically unique from others within their same subtype, such as variably protease-sensitive prionopathies, or exist as a mixture of subtypes within the same patient. Western blotting of brain tissue, along with the genotyping of codon 129 of the prion-encoding gene, is considered the "gold standard" for the biochemical characterization of CJD. Western blotting requires a significant amount of prion protein for detection, is labor-intensive, and is also associated with high interassay variability. In addition to these limitations, a growing body of research suggests that unique subtypes of CJD are often undetected or misdiagnosed using standard diagnostic western blotting protocols. Consequently, we successfully optimized and developed a capillary-based western assay using the JESS Simple Western (ProteinSimple) to detect and characterize prion proteins from patients with CJD. We found that this novel assay consistently differentiated CJD type 1 and type 2 cases with a limit of detection 10 to 100× higher than traditional western blotting. Cases with CJD in which type 1 and type 2 coexist within the same brain region can be detected using type 1-specific and type 2-specific antibodies, and we found that there was remarkable specificity for the detection of cases with variably protease-sensitive prionopathy. The assay presented displays outstanding sensitivity, allowing for the preservation of valuable samples and enhancing current detection methods.
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Affiliation(s)
- Jennifer Myskiw
- One Health Division, Public Health Agency of Canada, National Microbiology Laboratory, Winnipeg, Manitoba, Canada; Department of Medical Microbiology and Infectious Diseases, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Lise Lamoureux
- One Health Division, Public Health Agency of Canada, National Microbiology Laboratory, Winnipeg, Manitoba, Canada
| | - Anne Peterson
- One Health Division, Public Health Agency of Canada, National Microbiology Laboratory, Winnipeg, Manitoba, Canada
| | - David Knox
- One Health Division, Public Health Agency of Canada, National Microbiology Laboratory, Winnipeg, Manitoba, Canada
| | - Gerard H Jansen
- Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Michael B Coulthart
- Canadian Creutzfeldt-Jakob Disease Surveillance System, Public Health Agency of Canada, Ottawa, Ontario, Canada
| | - Stephanie A Booth
- One Health Division, Public Health Agency of Canada, National Microbiology Laboratory, Winnipeg, Manitoba, Canada; Department of Medical Microbiology and Infectious Diseases, Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada.
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4
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Nafe R, Arendt CT, Hattingen E. Human prion diseases and the prion protein - what is the current state of knowledge? Transl Neurosci 2023; 14:20220315. [PMID: 37854584 PMCID: PMC10579786 DOI: 10.1515/tnsci-2022-0315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 09/07/2023] [Accepted: 09/15/2023] [Indexed: 10/20/2023] Open
Abstract
Prion diseases and the prion protein are only partially understood so far in many aspects. This explains the continued research on this topic, calling for an overview on the current state of knowledge. The main objective of the present review article is to provide a comprehensive up-to-date presentation of all major features of human prion diseases bridging the gap between basic research and clinical aspects. Starting with the prion protein, current insights concerning its physiological functions and the process of pathological conversion will be highlighted. Diagnostic, molecular, and clinical aspects of all human prion diseases will be discussed, including information concerning rare diseases like prion-associated amyloidoses and Huntington disease-like 1, as well as the question about a potential human threat due to the transmission of prions from prion diseases of other species such as chronic wasting disease. Finally, recent attempts to develop future therapeutic strategies will be addressed.
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Affiliation(s)
- Reinhold Nafe
- Department of Neuroradiology, Clinics of Johann Wolfgang-Goethe University, Schleusenweg 2-16, 60528Frankfurt am Main, Germany
| | - Christophe T. Arendt
- Department of Neuroradiology, Clinics of Johann Wolfgang-Goethe University, Schleusenweg 2-16, 60528Frankfurt am Main, Germany
| | - Elke Hattingen
- Department of Neuroradiology, Clinics of Johann Wolfgang-Goethe University, Schleusenweg 2-16, 60528Frankfurt am Main, Germany
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Igel A, Fornara B, Rezaei H, Béringue V. Prion assemblies: structural heterogeneity, mechanisms of formation, and role in species barrier. Cell Tissue Res 2022; 392:149-166. [PMID: 36399162 PMCID: PMC10113350 DOI: 10.1007/s00441-022-03700-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 11/03/2022] [Indexed: 11/19/2022]
Abstract
AbstractPrions are proteinaceous pathogens responsible for a wide range of neurodegenerative diseases in animal and human. Prions are formed from misfolded, ß-sheet rich, and aggregated conformers (PrPSc) of the host-encoded prion protein (PrPC). Prion replication stems from the capacity of PrPSc to self-replicate by templating PrPC conversion and polymerization. The question then arises about the molecular mechanisms of prion replication, host invasion, and capacity to contaminate other species. Studying these mechanisms has gained in recent years further complexity with evidence that PrPSc is a pleiomorphic protein. There is indeed compelling evidence for PrPSc structural heterogeneity at different scales: (i) within prion susceptible host populations with the existence of different strains with specific biological features due to different PrPSc conformers, (ii) within a single infected host with the co-propagation of different strains, and (iii) within a single strain with evidence for co-propagation of PrPSc assemblies differing in their secondary to quaternary structure. This review summarizes current knowledge of prion assembly heterogeneity, potential mechanisms of formation during the replication process, and importance when crossing the species barrier.
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Gerstmann-Sträussler-Scheinker Disease with F198S Mutation Induces Independent Tau and Prion Protein Pathologies in Bank Voles. Biomolecules 2022; 12:biom12101537. [PMID: 36291746 PMCID: PMC9599806 DOI: 10.3390/biom12101537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 11/16/2022] Open
Abstract
Gerstmann–Sträussler–Scheinker disease (GSS) is a rare genetic prion disease. A large GSS kindred linked to the serine-for-phenylalanine substitution at codon 198 of the prion protein gene (GSS-F198S) is characterized by conspicuous accumulation of prion protein (PrP)-amyloid deposits and neurofibrillary tangles. Recently, we demonstrated the transmissibility of GSS-F198S prions to bank vole carrying isoleucine at 109 PrP codon (BvI). Here we investigated: (i) the transmissibility of GSS-F198S prions to voles carrying methionine at codon 109 (BvM); (ii) the induction of hyperphosphorylated Tau (pTau) in two vole lines, and (iii) compared the phenotype of GSS-F198S-induced pTau with pTau induced in BvM following intracerebral inoculation of a familial Alzheimer’s disease case carrying Presenilin 1 mutation (fAD-PS1). We did not detect prion transmission to BvM, despite the high susceptibility of BvI previously observed. Immunohistochemistry established the presence of induced pTau depositions in vole brains that were not affected by prions. Furthermore, the phenotype of pTau deposits in vole brains was similar in GSS-F198S and fAD-PS1. Overall, results suggest that, regardless of the cause of pTau deposition and its relationship with PrPSc in GSS-F198S human-affected brains, the two components possess their own seeding properties, and that pTau deposition is similarly induced by GSS-F198S and fAD-PS1.
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Pirisinu L, Di Bari MA, D’Agostino C, Vanni I, Riccardi G, Marcon S, Vaccari G, Chiappini B, Benestad SL, Agrimi U, Nonno R. A single amino acid residue in bank vole prion protein drives permissiveness to Nor98/atypical scrapie and the emergence of multiple strain variants. PLoS Pathog 2022; 18:e1010646. [PMID: 35731839 PMCID: PMC9255773 DOI: 10.1371/journal.ppat.1010646] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 07/05/2022] [Accepted: 06/03/2022] [Indexed: 12/03/2022] Open
Abstract
Prions are infectious agents that replicate through the autocatalytic misfolding of the cellular prion protein (PrPC) into infectious aggregates (PrPSc) causing fatal neurodegenerative diseases in humans and animals. Prions exist as strains, which are encoded by conformational variants of PrPSc. The transmissibility of prions depends on the PrPC sequence of the recipient host and on the incoming prion strain, so that some animal prion strains are more contagious than others or are transmissible to new species, including humans. Nor98/atypical scrapie (AS) is a prion disease of sheep and goats reported in several countries worldwide. At variance with classical scrapie (CS), AS is considered poorly contagious and is supposed to be spontaneous in origin. The zoonotic potential of AS, its strain variability and the relationships with the more contagious CS strains remain largely unknown. We characterized AS isolates from sheep and goats by transmission in ovinised transgenic mice (tg338) and in two genetic lines of bank voles, carrying either methionine (BvM) or isoleucine (BvI) at PrP residue 109. All AS isolates induced the same pathological phenotype in tg338 mice, thus proving that they encoded the same strain, irrespective of their geographical origin or source species. In bank voles, we found that the M109I polymorphism dictates the susceptibility to AS. BvI were susceptible and faithfully reproduced the AS strain, while the transmission in BvM was highly inefficient and was characterized by a conformational change towards a CS-like prion strain. Sub-passaging experiments revealed that the main strain component of AS is accompanied by minor CS-like strain components, which can be positively selected during replication in both AS-resistant or AS-susceptible animals. These findings add new clues for a better comprehension of strain selection dynamics in prion infections and have wider implications for understanding the origin of contagious prion strains, such as CS. Prions are transmissible agents responsible for fatal neurodegenerative diseases in humans and animals. Prions exist as strains, exhibiting distinct disease phenotypes and transmission properties. Some prion diseases occur sporadically with a supposedly spontaneous origin, while others are contagious and give rise to epidemics, mainly in animals. We investigated the strain properties of Nor98/atypical scrapie (AS), a sporadic prion disease of small ruminants. We found that AS was faithfully reproduced not only in a homologous context, i.e. ovinised transgenic mice, but also in an unrelated animal species, the bank vole. A natural polymorphism of the bank vole prion protein, coding for methionine (BvM) or for isoleucine (BvI) at codon 109, dictated the susceptibility of voles to AS, with BvI being highly susceptible to AS and BvM rather resistant. Most importantly, the M109I polymorphism mediated the emergence of AS-derived mutant prion strains resembling classical scrapie (CS), a contagious prion disease. Finally, by sub-passages in bank voles, we found that the main strain component of AS is accompanied by minor CS-like strain components, which can be positively selected during replication in both AS-resistant or AS-susceptible vole lines. These findings allow a better understanding of strain selection dynamics and suggest a link between sporadic and contagious prion diseases.
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Affiliation(s)
- Laura Pirisinu
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Michele Angelo Di Bari
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Claudia D’Agostino
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Ilaria Vanni
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Geraldina Riccardi
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Stefano Marcon
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Gabriele Vaccari
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Barbara Chiappini
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | | | - Umberto Agrimi
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
| | - Romolo Nonno
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Rome, Italy
- * E-mail:
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Transmission of cervid prions to humanized mice demonstrates the zoonotic potential of CWD. Acta Neuropathol 2022; 144:767-784. [PMID: 35996016 PMCID: PMC9468132 DOI: 10.1007/s00401-022-02482-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 08/05/2022] [Accepted: 08/07/2022] [Indexed: 01/28/2023]
Abstract
Prions cause infectious and fatal neurodegenerative diseases in mammals. Chronic wasting disease (CWD), a prion disease of cervids, spreads efficiently among wild and farmed animals. Potential transmission to humans of CWD is a growing concern due to its increasing prevalence. Here, we provide evidence for a zoonotic potential of CWD prions, and its probable signature using mice expressing human prion protein (PrP) as an infection model. Inoculation of these mice with deer CWD isolates resulted in atypical clinical manifestation with prion seeding activity and efficient transmissible infectivity in the brain and, remarkably, in feces, but without classical neuropathological or Western blot appearances of prion diseases. Intriguingly, the protease-resistant PrP in the brain resembled that found in a familial human prion disease and was transmissible upon second passage. Our results suggest that CWD might infect humans, although the transmission barrier is likely higher compared to zoonotic transmission of cattle prions. Notably, our data suggest a different clinical presentation, prion signature, and tissue tropism, which causes challenges for detection by current diagnostic assays. Furthermore, the presence of infectious prions in feces is concerning because if this occurs in humans, it is a source for human-to-human transmission. These findings have strong implications for public health and CWD management.
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Carta M, Aguzzi A. Molecular foundations of prion strain diversity. Curr Opin Neurobiol 2021; 72:22-31. [PMID: 34416480 DOI: 10.1016/j.conb.2021.07.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 07/09/2021] [Accepted: 07/14/2021] [Indexed: 12/15/2022]
Abstract
Despite being caused by a single protein, prion diseases are strikingly heterogenous. Individual prion variants, known as strains, possess distinct biochemical properties, form aggregates with characteristic morphologies and preferentially seed certain brain regions, causing markedly different disease phenotypes. Strain diversity is determined by protein structure, post-translational modifications and the presence of extracellular matrix components, with single amino acid substitutions or altered protein glycosylation exerting dramatic effects. Here, we review recent advances in the study of prion strains and discuss how a deeper knowledge of the molecular origins of strain heterogeneity is providing a foundation for the development of anti-prion therapeutics.
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Affiliation(s)
- Manfredi Carta
- Institute of Neuropathology, University Hospital of Zurich, University of Zurich, Schmelzbergstrasse 12, 8091 Zurich, Switzerland
| | - Adriano Aguzzi
- Institute of Neuropathology, University Hospital of Zurich, University of Zurich, Schmelzbergstrasse 12, 8091 Zurich, Switzerland.
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Hannaoui S, Triscott E, Duque Velásquez C, Chang SC, Arifin MI, Zemlyankina I, Tang X, Bollinger T, Wille H, McKenzie D, Gilch S. New and distinct chronic wasting disease strains associated with cervid polymorphism at codon 116 of the Prnp gene. PLoS Pathog 2021; 17:e1009795. [PMID: 34310662 PMCID: PMC8341689 DOI: 10.1371/journal.ppat.1009795] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/05/2021] [Accepted: 07/12/2021] [Indexed: 11/18/2022] Open
Abstract
Chronic wasting disease (CWD) is a prion disease affecting cervids. Polymorphisms in the prion protein gene can result in extended survival of CWD-infected animals. However, the impact of polymorphisms on cellular prion protein (PrPC) and prion properties is less understood. Previously, we characterized the effects of a polymorphism at codon 116 (A>G) of the white-tailed deer (WTD) prion protein and determined that it destabilizes PrPC structure. Comparing CWD isolates from WTD expressing homozygous wild-type (116AA) or heterozygous (116AG) PrP, we found that 116AG-prions were conformationally less stable, more sensitive to proteases, with lower seeding activity in cell-free conversion and reduced infectivity. Here, we aimed to understand CWD strain emergence and adaptation. We show that the WTD-116AG isolate contains two different prion strains, distinguished by their host range, biochemical properties, and pathogenesis from WTD-116AA prions (Wisc-1). Serial passages of WTD-116AG prions in tg(CerPrP)1536+/+ mice overexpressing wild-type deer-PrPC revealed two populations of mice with short and long incubation periods, respectively, and remarkably prolonged clinical phase upon inoculation with WTD-116AG prions. Inoculation of serially diluted brain homogenates confirmed the presence of two strains in the 116AG isolate with distinct pathology in the brain. Interestingly, deglycosylation revealed proteinase K-resistant fragments with different electrophoretic mobility in both tg(CerPrP)1536+/+ mice and Syrian golden hamsters infected with WTD-116AG. Infection of tg60 mice expressing deer S96-PrP with 116AG, but not Wisc-1 prions induced clinical disease. On the contrary, bank voles resisted 116AG prions, but not Wisc-1 infection. Our data indicate that two strains co-existed in the WTD-116AG isolate, expanding the variety of CWD prion strains. We argue that the 116AG isolate does not contain Wisc-1 prions, indicating that the presence of 116G-PrPC diverted 116A-PrPC from adopting a Wisc-1 structure. This can have important implications for their possible distinct capacities to cross species barriers into both cervids and non-cervids. Chronic wasting disease belongs to the family of prion diseases. It is considered the most contagious prion disease and the only one that affects free ranging wildlife. The disease range is expanding in North America and Northern Europe. This work describes the emergence and characterization of new chronic wasting disease strains related to a polymorphism in the prion protein gene. It supports the concept that strains are a dynamic mixture of substrains that can influence and interfere with each other. Because transmission barriers are governed by the compatibility of a particular prion strain with the new host’s prion protein, it is critical to understand the emergence and variety of chronic wasting disease strains circulating in wild animals and their ability to infect new host species including humans.
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Affiliation(s)
- Samia Hannaoui
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine; Hotchkiss Brain Institute; University of Calgary, Calgary, Canada
| | - Elizabeth Triscott
- Department of Biological Sciences, Center for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Canada
| | - Camilo Duque Velásquez
- Department of Biological Sciences, Center for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Canada
| | - Sheng Chun Chang
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine; Hotchkiss Brain Institute; University of Calgary, Calgary, Canada
| | - Maria Immaculata Arifin
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine; Hotchkiss Brain Institute; University of Calgary, Calgary, Canada
| | - Irina Zemlyankina
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine; Hotchkiss Brain Institute; University of Calgary, Calgary, Canada
| | - Xinli Tang
- Department of Biochemistry, Center for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Canada
| | - Trent Bollinger
- Western College of Veterinary Medicine, University of Saskatchewan, Canadian Wildlife Health Cooperative (CWHC), Saskatoon, Saskatchewan, Canada
| | - Holger Wille
- Department of Biochemistry, Center for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Canada
| | - Debbie McKenzie
- Department of Biological Sciences, Center for Prions and Protein Folding Diseases, University of Alberta, Edmonton, Canada
| | - Sabine Gilch
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine; Hotchkiss Brain Institute; University of Calgary, Calgary, Canada
- * E-mail:
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11
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Gambetti P. Autobiography Series: A Life of Anecdotes. J Neuropathol Exp Neurol 2021. [DOI: 10.1093/jnen/nlab021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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12
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Further Characterization of Glycoform-Selective Prions of Variably Protease-Sensitive Prionopathy. Pathogens 2021; 10:pathogens10050513. [PMID: 33922765 PMCID: PMC8146342 DOI: 10.3390/pathogens10050513] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/10/2021] [Accepted: 04/15/2021] [Indexed: 11/17/2022] Open
Abstract
Prion is an infectious protein (PrPSc) that is derived from a cellular glycoprotein (PrPC) through a conformational transition and associated with a group of prion diseases in animals and humans. Characterization of proteinase K (PK)-resistant PrPSc by western blotting has been critical to diagnosis and understanding of prion diseases including Creutzfeldt-Jakob disease (CJD) and Gerstmann-Sträussler-Scheinker (GSS) disease in humans. However, formation as well as biochemical and biological properties of the glycoform-selective PrPSc in variably protease-sensitive prionopathy (VPSPr) remain poorly understood. Here we reveal that formation of the ladder-like PrPSc in VPSPr is a PK-dependent two-step process, which is enhanced by basic pH. Two sets of PrPSc fragments can be identified with antibodies directed against an intermediate or a C-terminal domain of the protein. Moreover, antibodies directed against specific PrP glycoforms reveal faster electrophoretic migrations of PrP fragments mono-glycosylated at residue 181 and 197 in VPSPr than those in sporadic CJD (sCJD). Finally, RT-QuIC assay indicates that PrPSc-seeding activity is lower and its lag time is longer in VPSPr than in sCJD. Our results suggest that the glycoform-selective PrPSc in VPSPr is associated with altered glycosylation, resulting in different PK-truncation and aggregation seeding activity compared to PrPSc in sCJD.
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13
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Huntington's disease: lessons from prion disorders. J Neurol 2021; 268:3493-3504. [PMID: 33625583 DOI: 10.1007/s00415-021-10418-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 02/06/2023]
Abstract
Decades of research on the prion protein and its associated diseases have caused a paradigm shift in our understanding of infectious agents. More recent years have been marked by a surge of studies supporting the application of these findings to a broad array of neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Here, we present evidence to suggest that Huntington's disease, a monogenic disorder of the central nervous system, shares features with prion disorders and that, it too, may be governed by similar mechanisms. We further posit that these similarities could suggest that, like other common neurodegenerative disorders, sporadic forms of Huntington's disease may exist.
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14
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Bélondrade M, Nicot S, Mayran C, Bruyere-Ostells L, Almela F, Di Bari MA, Levavasseur E, Watts JC, Fournier-Wirth C, Lehmann S, Haïk S, Nonno R, Bougard D. Sensitive protein misfolding cyclic amplification of sporadic Creutzfeldt-Jakob disease prions is strongly seed and substrate dependent. Sci Rep 2021; 11:4058. [PMID: 33603091 PMCID: PMC7893054 DOI: 10.1038/s41598-021-83630-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 02/05/2021] [Indexed: 12/11/2022] Open
Abstract
Unlike variant Creutzfeldt–Jakob disease prions, sporadic Creutzfeldt–Jakob disease prions have been shown to be difficult to amplify in vitro by protein misfolding cyclic amplification (PMCA). We assessed PMCA of pathological prion protein (PrPTSE) from 14 human sCJD brain samples in 3 substrates: 2 from transgenic mice expressing human prion protein (PrP) with either methionine (M) or valine (V) at position 129, and 1 from bank voles. Brain extracts representing the 5 major clinicopathological sCJD subtypes (MM1/MV1, MM2, MV2, VV1, and VV2) all triggered seeded PrPTSE amplification during serial PMCA with strong seed- and substrate-dependence. Remarkably, bank vole PrP substrate allowed the propagation of all sCJD subtypes with preservation of the initial molecular PrPTSE type. In contrast, PMCA in human PrP substrates was accompanied by a PrPTSE molecular shift during heterologous (M/V129) PMCA reactions, with increased permissiveness of V129 PrP substrate to in vitro sCJD prion amplification compared to M129 PrP substrate. Combining PMCA amplification sensitivities with PrPTSE electrophoretic profiles obtained in the different substrates confirmed the classification of 4 distinct major sCJD prion strains (M1, M2, V1, and V2). Finally, the level of sensitivity required to detect VV2 sCJD prions in cerebrospinal fluid was achieved.
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Affiliation(s)
- Maxime Bélondrade
- Pathogenesis and Control of Chronic Infections, Etablissement Français du Sang, Inserm, Université de Montpellier, Montpellier, France
| | - Simon Nicot
- Pathogenesis and Control of Chronic Infections, Etablissement Français du Sang, Inserm, Université de Montpellier, Montpellier, France
| | - Charly Mayran
- Pathogenesis and Control of Chronic Infections, Etablissement Français du Sang, Inserm, Université de Montpellier, Montpellier, France
| | - Lilian Bruyere-Ostells
- Pathogenesis and Control of Chronic Infections, Etablissement Français du Sang, Inserm, Université de Montpellier, Montpellier, France
| | - Florian Almela
- Pathogenesis and Control of Chronic Infections, Etablissement Français du Sang, Inserm, Université de Montpellier, Montpellier, France
| | - Michele A Di Bari
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanita, Rome, Italy
| | - Etienne Levavasseur
- Inserm U 1127, CNRS UMR 7225, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, Sorbonne Universités, Paris, France
| | - Joel C Watts
- Tanz Centre for Research in Neurodegenerative Diseases and Department of Biochemistry, University of Toronto, Toronto, Canada
| | - Chantal Fournier-Wirth
- Pathogenesis and Control of Chronic Infections, Etablissement Français du Sang, Inserm, Université de Montpellier, Montpellier, France
| | - Sylvain Lehmann
- IRMB, INM, INSERM, CHU Montpellier, (LBPC-PPC), Univ Montpellier, Montpellier, France
| | - Stéphane Haïk
- Inserm U 1127, CNRS UMR 7225, UPMC Université Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, Sorbonne Universités, Paris, France
| | - Romolo Nonno
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanita, Rome, Italy
| | - Daisy Bougard
- Pathogenesis and Control of Chronic Infections, Etablissement Français du Sang, Inserm, Université de Montpellier, Montpellier, France.
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15
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Nonno R, Di Bari MA, Pirisinu L, D'Agostino C, Vanni I, Chiappini B, Marcon S, Riccardi G, Tran L, Vikøren T, Våge J, Madslien K, Mitchell G, Telling GC, Benestad SL, Agrimi U. Studies in bank voles reveal strain differences between chronic wasting disease prions from Norway and North America. Proc Natl Acad Sci U S A 2020; 117:31417-31426. [PMID: 33229531 PMCID: PMC7733848 DOI: 10.1073/pnas.2013237117] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 11/03/2020] [Indexed: 12/19/2022] Open
Abstract
Chronic wasting disease (CWD) is a relentless epidemic disorder caused by infectious prions that threatens the survival of cervid populations and raises increasing public health concerns in North America. In Europe, CWD was detected for the first time in wild Norwegian reindeer (Rangifer tarandus) and moose (Alces alces) in 2016. In this study, we aimed at comparing the strain properties of CWD prions derived from different cervid species in Norway and North America. Using a classical strain typing approach involving transmission and adaptation to bank voles (Myodes glareolus), we found that prions causing CWD in Norway induced incubation times, neuropathology, regional deposition of misfolded prion protein aggregates in the brain, and size of their protease-resistant core, different from those that characterize North American CWD. These findings show that CWD prion strains affecting Norwegian cervids are distinct from those found in North America, implying that the highly contagious North American CWD prions are not the proximate cause of the newly discovered Norwegian CWD cases. In addition, Norwegian CWD isolates showed an unexpected strain variability, with reindeer and moose being caused by different CWD strains. Our findings shed light on the origin of emergent European CWD, have significant implications for understanding the nature and the ecology of CWD in Europe, and highlight the need to assess the zoonotic potential of the new CWD strains detected in Europe.
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Affiliation(s)
- Romolo Nonno
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy;
| | - Michele A Di Bari
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Laura Pirisinu
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Claudia D'Agostino
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Ilaria Vanni
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Barbara Chiappini
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Stefano Marcon
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Geraldina Riccardi
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
| | - Linh Tran
- World Organization for Animal Health Reference Laboratory for Chronic Wasting Disease, Norwegian Veterinary Institute, N-0106 Oslo, Norway
| | - Turid Vikøren
- World Organization for Animal Health Reference Laboratory for Chronic Wasting Disease, Norwegian Veterinary Institute, N-0106 Oslo, Norway
| | - Jørn Våge
- World Organization for Animal Health Reference Laboratory for Chronic Wasting Disease, Norwegian Veterinary Institute, N-0106 Oslo, Norway
| | - Knut Madslien
- World Organization for Animal Health Reference Laboratory for Chronic Wasting Disease, Norwegian Veterinary Institute, N-0106 Oslo, Norway
| | - Gordon Mitchell
- National and World Organization for Animal Health Reference Laboratory for Scrapie and Chronic Wasting Disease, Canadian Food Inspection Agency, Ottawa, ON K2H 8P9, Canada
| | - Glenn C Telling
- Prion Research Center, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80525
| | - Sylvie L Benestad
- World Organization for Animal Health Reference Laboratory for Chronic Wasting Disease, Norwegian Veterinary Institute, N-0106 Oslo, Norway
| | - Umberto Agrimi
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, 00161 Rome, Italy
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16
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Arshad H, Bourkas MEC, Watts JC. The utility of bank voles for studying prion disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 175:179-211. [PMID: 32958232 DOI: 10.1016/bs.pmbts.2020.08.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The transmission of prions between species is typically an inefficient process due to the species barrier, which represents incompatibility between prion seed and substrate molecules. Bank voles (Myodes glareolus) are an exception to this rule, as they are susceptible to a diverse range of prion strains from many different animal species. In particular, bank voles can be efficiently infected with most types of human prions and have played a critical role in validating variably protease-sensitive prionopathy (VPSPr) and certain forms of Gerstmann-Sträussler-Scheinker (GSS) disease as bona fide prion disorders rather than non-transmissible proteinopathies. The bank vole prion protein (BVPrP) confers a "universal prion acceptor" phenotype when expressed in mice and when used as a substrate for in vitro prion amplification assays, indicating that the unique prion transmission properties of bank voles are mediated by BVPrP. Over-expression of BVPrP in mice can also promote the spontaneous development of prion disease, indicating that BVPrP is intrinsically prone to both spontaneous and template-directed misfolding. Here, we discuss the utility of bank voles and BVPrP for prion research and how they have provided new tools for establishing rapid animal bioassays, modeling spontaneous prion disease, standardizing prion diagnostics, and understanding the molecular basis of the species barrier.
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Affiliation(s)
- Hamza Arshad
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Matthew E C Bourkas
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Joel C Watts
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada; Department of Biochemistry, University of Toronto, Toronto, ON, Canada.
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17
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Krance SH, Luke R, Shenouda M, Israwi AR, Colpitts SJ, Darwish L, Strauss M, Watts JC. Cellular models for discovering prion disease therapeutics: Progress and challenges. J Neurochem 2020; 153:150-172. [PMID: 31943194 DOI: 10.1111/jnc.14956] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/07/2020] [Accepted: 01/08/2020] [Indexed: 12/22/2022]
Abstract
Prions, which cause fatal neurodegenerative disorders such as Creutzfeldt-Jakob disease, are misfolded and infectious protein aggregates. Currently, there are no treatments available to halt or even delay the progression of prion disease in the brain. The infectious nature of prions has resulted in animal paradigms that accurately recapitulate all aspects of prion disease, and these have proven to be instrumental for testing the efficacy of candidate therapeutics. Nonetheless, infection of cultured cells with prions provides a much more powerful system for identifying molecules capable of interfering with prion propagation. Certain lines of cultured cells can be chronically infected with various types of mouse prions, and these models have been used to unearth candidate anti-prion drugs that are at least partially efficacious when administered to prion-infected rodents. However, these studies have also revealed that not all types of prions are equal, and that drugs active against mouse prions are not necessarily effective against prions from other species. Despite some recent progress, the number of cellular models available for studying non-mouse prions remains limited. In particular, human prions have proven to be particularly challenging to propagate in cultured cells, which has severely hindered the discovery of drugs for Creutzfeldt-Jakob disease. In this review, we summarize the cellular models that are presently available for discovering and testing drugs capable of blocking the propagation of prions and highlight challenges that remain on the path towards developing therapies for prion disease.
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Affiliation(s)
- Saffire H Krance
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada.,Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Russell Luke
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Marc Shenouda
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.,Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada
| | - Ahmad R Israwi
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Sarah J Colpitts
- Department of Immunology, University of Toronto, Toronto, ON, Canada
| | - Lina Darwish
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada.,Hurvitz Brain Sciences Program, Sunnybrook Research Institute, Toronto, ON, Canada
| | - Maximilian Strauss
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada.,Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada
| | - Joel C Watts
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Toronto, ON, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON, Canada
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18
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Understanding Prion Strains: Evidence from Studies of the Disease Forms Affecting Humans. Viruses 2019; 11:v11040309. [PMID: 30934971 PMCID: PMC6520670 DOI: 10.3390/v11040309] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 03/25/2019] [Accepted: 03/26/2019] [Indexed: 12/11/2022] Open
Abstract
Prion diseases are a unique group of rare neurodegenerative disorders characterized by tissue deposition of heterogeneous aggregates of abnormally folded protease-resistant prion protein (PrPSc), a broad spectrum of disease phenotypes and a variable efficiency of disease propagation in vivo. The dominant clinicopathological phenotypes of human prion disease include Creutzfeldt–Jakob disease, fatal insomnia, variably protease-sensitive prionopathy, and Gerstmann–Sträussler–Scheinker disease. Prion disease propagation into susceptible hosts led to the isolation and characterization of prion strains, initially operatively defined as “isolates” causing diseases with distinctive characteristics, such as the incubation period, the pattern of PrPSc distribution, and the regional severity of neuropathological changes after injection into syngeneic hosts. More recently, the structural basis of prion strains has been linked to amyloid polymorphs (i.e., variant amyloid protein conformations) and the concept extended to all protein amyloids showing polymorphic structures and some evidence of in vivo or in vitro propagation by seeding. Despite the significant advances, however, the link between amyloid structure and disease is not understood in many instances. Here we reviewed the most significant contributions of human prion disease studies to current knowledge of the molecular basis of phenotypic variability and the prion strain phenomenon and underlined the unsolved issues from the human disease perspective.
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