Coinfecting Prion Strains Compete for a Limiting Cellular Resource

ABSTRACT Prion strain interference can influence the emergence of a dominant strain from a mixture; however, the mechanisms underlying prion strain interference are poorly understood. In our model of strain interference, inoculation of the sciatic nerve with the drowsy (DY) strain of the transmissible mink encephalopathy (TME) agent prior to superinfection with the hyper (HY) strain of TME can completely block HY TME from causing disease. We show here that the deposition of PrPSc, in the absence of neuronal loss or spongiform change, in the central nervous system corresponds with the ability of DY TME to block HY TME infection. This suggests that DY TME agent-induced damage is not responsible for strain interference but rather prions compete for a cellular resource. We show that protein misfolding cyclic amplification (PMCA) of DY and HY TME maintains the strain-specific properties of PrPSc and replicates infectious agent and that DY TME can interfere, or completely block, the emergence of HY TME. DY PrPSc does not convert all of the available PrPC to PrPSc in PMCA, suggesting the mechanism of prion strain interference is due to the sequestering of PrPC and/or other cellular components required for prion conversion. The emergence of HY TME in PMCA was controlled by the initial ratio of the TME agents. A higher ratio of DY to HY TME agent is required for complete blockage of HY TME in PMCA compared to several previous in vivo studies, suggesting that HY TME persists in animals coinfected with the two strains. This was confirmed by PMCA detection of HY PrPSc in animals where DY TME had completely blocked HY TME from causing disease.

Download Full-text

The emergence of classical BSE from atypical/Nor98 scrapie

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1915737116 ◽

2019 ◽

Vol 116 (52) ◽

pp. 26853-26862 ◽

Cited By ~ 6

Author(s):

Alvina Huor ◽

Juan Carlos Espinosa ◽

Enric Vidal ◽

Hervé Cassard ◽

Jean-Yves Douet ◽

...

Keyword(s):

Prion Disease ◽

Protein Misfolding ◽

Small Ruminants ◽

Public Health Perspective ◽

Prion Strain ◽

Low Levels ◽

Insight Into ◽

New Occurrences

Atypical/Nor98 scrapie (AS) is a prion disease of small ruminants. Currently there are no efficient measures to control this form of prion disease, and, importantly, the zoonotic potential and the risk that AS might represent for other farmed animal species remains largely unknown. In this study, we investigated the capacity of AS to propagate in bovine PrP transgenic mice. Unexpectedly, the transmission of AS isolates originating from 5 different European countries to bovine PrP mice resulted in the propagation of the classical BSE (c-BSE) agent. Detection of prion seeding activity in vitro by protein misfolding cyclic amplification (PMCA) demonstrated that low levels of the c-BSE agent were present in the original AS isolates. C-BSE prion seeding activity was also detected in brain tissue of ovine PrP mice inoculated with limiting dilutions (endpoint titration) of ovine AS isolates. These results are consistent with the emergence and replication of c-BSE prions during the in vivo propagation of AS isolates in the natural host. These data also indicate that c-BSE prions, a known zonotic agent in humans, can emerge as a dominant prion strain during passage of AS between different species. These findings provide an unprecedented insight into the evolution of mammalian prion strain properties triggered by intra- and interspecies passage. From a public health perspective, the presence of c-BSE in AS isolates suggest that cattle exposure to small ruminant tissues and products could lead to new occurrences of c-BSE.

Download Full-text

Is the hypotensive effect of clonidine and related drugs due to imidazoline binding sites?

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1997.273.5.r1580 ◽

1997 ◽

Vol 273 (5) ◽

pp. R1580-R1584 ◽

Cited By ~ 15

Author(s):

Patrice G. Guyenet

Keyword(s):

Binding Sites ◽

Hypotensive Effect ◽

Genetically Engineered ◽

Therapeutic Effects ◽

Genetically Engineered Mice ◽

Wide Range ◽

The Central Nervous System ◽

Imidazoline Binding Sites ◽

Cellular Components

Clonidine and related α2-adrenergic receptor (α2AR) agonists lower arterial pressure primarily by an action within the central nervous system. These drugs also have varying degrees of affinity for other cellular components called nonadrenergic imidazoline binding sites (NAIBS). For over 20 years, the α2AR agonist activity of clonidine-like drugs was thought to account for their therapeutic effects (α2 theory). However, several groups have recently proposed a competing “imidazoline theory” according to which the hypotensive effect of clonidine-like drugs would in fact owe more to their affinity for one type of NAIBS, called I1receptors. The α2-theory is strongly supported by four main types of congruent data. First, the hypotensive effect of systemically administered clonidine is blocked by α2AR antagonists that are without affinity for I1 NAIBs. Second, the hypotensive effect of intravenous clonidine is absent in genetically engineered mice in which a defective α2AAR has been substituted for the normal one. Third, the sympatholytic effect of clonidine is consistent with the presence of conventional inhibitory α2ARs on sympathetic preganglionic neurons and on their main excitatory inputs in the medulla oblongata. Fourth, the first I1 ligand without affinity for α2ARs was found to be biologically inactive. The imidazoline theory is supported by a limited repertoire of whole animal “in vivo” pharmacological experiments that remain open to a wide range of interpretations. In conclusion, the bulk of the evidence strongly supports a largely predominant role of α2AR mechanisms in the action of most clonidine-like agents at therapeutically relevant doses or concentrations. Even the small pharmacological differences between these agents cannot yet be linked with certainty to their relative affinity for I1 NAIBS.

Download Full-text

A New Cell Model for Investigating Prion Strain Selection and Adaptation

Viruses ◽

10.3390/v11100888 ◽

2019 ◽

Vol 11 (10) ◽

pp. 888

Author(s):

Alexandra Philiastides ◽

Juan Manuel Ribes ◽

Daniel Chun-Mun Yip ◽

Christian Schmidt ◽

Iryna Benilova ◽

...

Keyword(s):

Molecular Mechanisms ◽

Cell Model ◽

Prion Diseases ◽

Neuroblastoma Cell ◽

Neuroblastoma Cell Line ◽

Strain Selection ◽

Prion Strain ◽

Prion Strains

Prion diseases are fatal neurodegenerative diseases that affect humans and animals. Prion strains, conformational variants of misfolded prion proteins, are associated with distinct clinical and pathological phenotypes. Host-strain interactions result in the selective damage of distinct brain areas and they are responsible for strain selection and/or adaptation, but the underlying molecular mechanisms are unknown. Prion strains can be distinguished by their cell tropism in vivo and in vitro, which suggests that susceptibility to distinct prion strains is determined by cellular factors. The neuroblastoma cell line PK1 is refractory to the prion strain Me7, but highly susceptible to RML. We challenged a large number of clonal PK1 lines with Me7 and successfully selected highly Me7-susceptible subclones (PME) to investigate whether the prion strain repertoire of PK1 can be expanded. Notably, the Me7-infected PME clones were more protease-resistant when compared to RML-infected PME clones, which suggested that cell-adapted Me7 and RML are distinct prion strains. Strikingly, Me7-refractory cells, including PK1 and astrocytes in cortico-hippocampal cultures, are highly susceptible to prions, being derived from homogenates of Me7-infected PME cells, suggesting that the passage of Me7 in PME cells leads to an extended host range. Thus, PME clones represent a compelling cell model for strain selection and adaptation.

Download Full-text

Emergence of multiple prion strains from single isolates of ovine scrapie

Journal of General Virology ◽

10.1099/vir.0.028886-0 ◽

2011 ◽

Vol 92 (6) ◽

pp. 1482-1491 ◽

Cited By ~ 47

Author(s):

Alana M. Thackray ◽

Lee Hopkins ◽

Richard Lockey ◽

John Spiropoulos ◽

Raymond Bujdoso

Keyword(s):

Transgenic Mice ◽

Incubation Time ◽

Infectious Agent ◽

Serial Passage ◽

Molecular Profile ◽

Strain Typing ◽

Wild Type ◽

Diverse Range ◽

Prion Strain ◽

Prion Strains

The infectious agent associated with prion diseases such as ovine scrapie shows strain diversity. Ovine prion strains have typically been identified by their transmission properties in wild-type mice. However, strain typing of ovine scrapie isolates in wild-type mice may not reveal properties of the infectious prion agent as they exist in the original host. This could be circumvented if ovine scrapie isolates are passaged in ovine prion protein (PrP)-transgenic mice. This study used incubation time, lesion profile, immunohistochemistry of the disease-associated PrP (PrPSc) and molecular profile to compare the range of ovine prion strains that emerged from sheep scrapie isolates following serial passage in wild-type and ovine PrP transgenic mice. It was found that a diverse range of ovine prion strains emerged from homozygous ARQ and VRQ scrapie isolates passaged in wild-type and ovine PrP transgenic mice. However, strain-specific PrPSc deposition and PrP27–30 molecular profile patterns were identified in ovine PrP transgenic mice that were not detected in wild-type mice. Significantly, it was established that the individual mouse brain selected for transmission during prion strain typing had a significant influence on strain definition. Serial passage of short- and long-incubation-time animals from the same group of scrapie-inoculated mice revealed different prion strain phenotypes. These observations are consistent with the possibility that some scrapie isolates contain more than one prion strain.

Download Full-text

Prion Strain Targeting Independent of Strain-Specific Neuronal Tropism

Journal of Virology ◽

10.1128/jvi.01745-08 ◽

2008 ◽

Vol 83 (1) ◽

pp. 81-87 ◽

Cited By ~ 26

Author(s):

Jacob I. Ayers ◽

Anthony E. Kincaid ◽

Jason C. Bartz

Keyword(s):

Differential Susceptibility ◽

Underlying Mechanism ◽

Clinical Disease ◽

Prion Strain ◽

Deposition Patterns ◽

Prion Infection ◽

The Central Nervous System ◽

Motor Tracts ◽

Spongiform Degeneration ◽

Transmissible Mink Encephalopathy

ABSTRACT While neuropathological features that define prion strains include spongiform degeneration and deposition patterns of PrPSc, the underlying mechanism for the strain-specific differences in PrPSc targeting is not known. To investigate prion strain targeting, we inoculated hamsters in the sciatic nerve with either the hyper (HY) or drowsy (DY) strain of the transmissible mink encephalopathy (TME) agent. Both TME strains were initially retrogradely transported in the central nervous system (CNS) exclusively by four descending motor tracts. The locations of HY and DY PrPSc deposition were identical throughout the majority of the incubation period. However, differences in PrPSc deposition between these strains were observed upon development of clinical disease. The differences observed were unlikely to be due to strain-specific neuronal tropism, since comparison of PrPSc deposition patterns by different routes of infection indicated that all brain areas were susceptible to prion infection by both TME strains. These findings suggest that prion transport and differential susceptibility to prion infection are not solely responsible for prion strain targeting. The data suggest that differences in PrPSc distribution between strains during clinical disease are due to differences in the length of time that PrPSc has to spread in the CNS before the host succumbs to disease.

Download Full-text

No influence of amyloid-β-degrading neprilysin activity on prion pathogenesis

Journal of General Virology ◽

10.1099/vir.0.80811-0 ◽

2005 ◽

Vol 86 (6) ◽

pp. 1861-1867 ◽

Cited By ~ 4

Author(s):

Markus Glatzel ◽

M. Hasan Mohajeri ◽

Raphael Poirier ◽

Roger M. Nitsch ◽

Petra Schwarz ◽

...

Keyword(s):

Gene Dosage ◽

Amyloid Β ◽

Infectious Agent ◽

Transmissible Spongiform Encephalopathies ◽

Substantial Evidence ◽

Spongiform Encephalopathies ◽

Amyloidogenic Proteins ◽

The Central Nervous System ◽

Rule Out

Transmissible spongiform encephalopathies are characterized by the accumulation of PrPSc, a protease-resistant form of a host-derived protein termed PrPC. Substantial evidence indicates that PrPSc represents an essential component of the infectious agent, which is termed prion. The accumulation of PrPSc within the central nervous system of prion-infected organisms is a dynamic process that is regulated both by production and by clearance of PrPSc. Although several proteases have been implicated in proteolysis of PrPC, the mechanisms underlying proteolysis of PrPSc remain unclear. Here, it was investigated whether neprilysin, a metalloprotease known to degrade extracellular amyloidogenic proteins such as amyloid-β, plays a role in prion pathogenesis in vivo. As neprilysin has a broad substrate specificity and is localized subcellularly in the vicinity of PrP, it represents a plausible candidate for prion degradation. Prions were therefore administered to mice lacking or overexpressing neprilysin in brain. However, the gene dosage of neprilysin did not modulate accumulation of PrPSc in brain. Also, incubation times and clinical course of prion disease, as well as brain infectivity titres at terminal stage, were unaffected. These data rule out neprilysin as a major modulator of PrPSc accumulation and prion pathogenesis.

Download Full-text

Central inhibition of P2Y12R differentially regulates survival and neuronal loss in MPTP-induced Parkinsonism in mice

10.1101/2021.02.03.256941 ◽

2021 ◽

Author(s):

András Iring ◽

Adrián Tóth ◽

Mária Baranyi ◽

Lilla Otrokocsi ◽

László V. Módis ◽

...

Keyword(s):

Disease Progression ◽

Disease Onset ◽

Neuronal Loss ◽

Cell Loss ◽

P2y12 Receptor ◽

Mapk Activity ◽

Central Inhibition ◽

The Central Nervous System ◽

And Control

AbstractParkinson’s disease (PD) is a chronic, progressive neurodegenerative condition; characterized with the degeneration of the nigrostriatal dopaminergic pathway and neuroinflammation. During PD progression, microglia, the resident immune cells in the central nervous system (CNS) display altered activity, but their role in maintaining PD development has remained unclear to date. The purinergic P2Y12 receptor (P2Y12R), which is exclusively expressed on the microglia in the CNS has been shown to regulate microglial activity and responses; however, the function of the P2Y12R in PD is unknown. Here we show that while pharmacological or genetic targeting of P2Y12R previous to disease onset augments acute mortality, these interventions protect against neurodegenerative cell loss and the development of neuroinflammation in vivo. Pharmacological inhibition of receptors during disease development reverses the symptoms of PD and halts disease progression. We found that P2Y12R regulate ROCK and p38 MAPK activity and control cytokine production. Understanding protective and detrimental P2Y12 receptor-mediated actions in the CNS may reveal novel approaches to control neuroinflammation and modify disease progression in PD.

Download Full-text

Porcine Prion Protein as a Paradigm of Limited Susceptibility to Prion Strain Propagation

The Journal of Infectious Diseases ◽

10.1093/infdis/jiz646 ◽

2020 ◽

Cited By ~ 2

Author(s):

Juan Carlos Espinosa ◽

Alba Marín-Moreno ◽

Patricia Aguilar-Calvo ◽

Sylvie L Benestad ◽

Olivier Andreoletti ◽

...

Keyword(s):

Prion Protein ◽

Protein Misfolding ◽

Prion Diseases ◽

Conformational Flexibility ◽

Cellular Prion Protein ◽

Spongiform Encephalopathy ◽

Prion Strain ◽

Experimental Transmission ◽

Prion Strains ◽

Jakob Disease

Abstract Although experimental transmission of bovine spongiform encephalopathy (BSE) to pigs and transgenic mice expressing pig cellular prion protein (PrPC) (porcine PrP [PoPrP]–Tg001) has been described, no natural cases of prion diseases in pig were reported. This study analyzed pig-PrPC susceptibility to different prion strains using PoPrP-Tg001 mice either as animal bioassay or as substrate for protein misfolding cyclic amplification (PMCA). A panel of isolates representatives of different prion strains was selected, including classic and atypical/Nor98 scrapie, atypical-BSE, rodent scrapie, human Creutzfeldt-Jakob-disease and classic BSE from different species. Bioassay proved that PoPrP-Tg001-mice were susceptible only to the classic BSE agent, and PMCA results indicate that only classic BSE can convert pig-PrPC into scrapie-type PrP (PrPSc), independently of the species origin. Therefore, conformational flexibility constraints associated with pig-PrP would limit the number of permissible PrPSc conformations compatible with pig-PrPC, thus suggesting that pig-PrPC may constitute a paradigm of low conformational flexibility that could confer high resistance to the diversity of prion strains.

Download Full-text

Incongruity between Prion Conversion and Incubation Period following Coinfection

Journal of Virology ◽

10.1128/jvi.00409-16 ◽

2016 ◽

Vol 90 (12) ◽

pp. 5715-5723 ◽

Cited By ~ 7

Author(s):

Katie A. Langenfeld ◽

Ronald A. Shikiya ◽

Anthony E. Kincaid ◽

Jason C. Bartz

Keyword(s):

Sciatic Nerve ◽

Incubation Period ◽

Single Strain ◽

Prion Strains ◽

Incubation Periods ◽

Growing Body ◽

Transneuronal Transport ◽

Transmissible Mink Encephalopathy ◽

Definition Of ◽

Prion Conversion

ABSTRACTWhen multiple prion strains are inoculated into the same host, they can interfere with each other. Strains with long incubation periods can suppress conversion of strains with short incubation periods; however, nothing is known about the conversion of the long-incubation-period strain during strain interference. To investigate this, we inoculated hamsters in the sciatic nerve with long-incubation-period strain 139H prior to superinfection with the short-incubation-period hyper (HY) strain of transmissible mink encephalopathy (TME). First, we found that 139H is transported along the same neuroanatomical tracks as HY TME, adding to the growing body of evidence indicating that PrPScfavors retrograde transneuronal transport. In contrast to a previous report, we found that 139H interferes with HY TME infection, which is likely due to both strains targeting the same population of neurons following sciatic nerve inoculation. Under conditions where 139H blocked HY TME from causing disease, the strain-specific properties of PrPSccorresponded with the strain that caused disease, consistent with our previous findings. In the groups of animals where incubation periods were not altered, we found that the animals contained a mixture of 139H and HY TME PrPSc. This finding expands the definition of strain interference to include conditions where PrPScformation is altered yet disease outcome is unaltered. Overall, these results contradict the premise that prion strains are static entities and instead suggest that strain mixtures are dynamic regardless of incubation period or clinical outcome of disease.IMPORTANCEPrions can exist as a mixture of strains in naturally infected animals, where they are able to interfere with the conversion of each other and to extend incubation periods. Little is known, however, about the dynamics of strain conversion under conditions where incubation periods are not affected. We found that inoculation of the same animal with two strains can result in the alteration of conversion of both strains under conditions where the resulting disease was consistent with infection with only a single strain. These data challenge the idea that prion strains are static and suggests that strain mixtures are more dynamic than previously appreciated. This observation has significant implications for prion adaptation.

Download Full-text

Chronic wasting disease (CWD) prion strains evolve via adaptive diversification of conformers in hosts expressing prion protein polymorphisms

Journal of Biological Chemistry ◽

10.1074/jbc.ra120.012546 ◽

2020 ◽

Vol 295 (15) ◽

pp. 4985-5001 ◽

Cited By ~ 2

Author(s):

Camilo Duque Velásquez ◽

Chae Kim ◽

Tracy Haldiman ◽

Chiye Kim ◽

Allen Herbst ◽

...

Keyword(s):

Prion Protein ◽

Protein Misfolding ◽

Chronic Wasting Disease ◽

Cellular Prion Protein ◽

Wasting Disease ◽

Prion Strain ◽

Adaptive Diversification ◽

Prion Strains ◽

Prion Transmission ◽

Conformation Stability

Chronic wasting disease (CWD) is caused by an unknown spectrum of prions and has become enzootic in populations of cervid species that express cellular prion protein (PrPC) molecules varying in amino acid composition. These PrPC polymorphisms can affect prion transmission, disease progression, neuropathology, and emergence of new prion strains, but the mechanistic steps in prion evolution are not understood. Here, using conformation-dependent immunoassay, conformation stability assay, and protein-misfolding cyclic amplification, we monitored the conformational and phenotypic characteristics of CWD prions passaged through deer and transgenic mice expressing different cervid PrPC polymorphisms. We observed that transmission through hosts with distinct PrPC sequences diversifies the PrPCWD conformations and causes a shift toward oligomers with defined structural organization, replication rate, and host range. When passaged in host environments that restrict prion replication, distinct co-existing PrPCWD conformers underwent competitive selection, stabilizing a new prion strain. Nonadaptive conformers exhibited unstable replication and accumulated only to low levels. These results suggest a continuously evolving diversity of CWD conformers and imply a critical interplay between CWD prion plasticity and PrPC polymorphisms during prion strain evolution.

Download Full-text