Sensitive protein misfolding cyclic amplification of sporadic Creutzfeldt-Jakob disease prions is strongly seed and substrate dependent.

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 (PrP) 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 PrP amplification during serial PMCA with strong seed- and substrate-dependence.

Neuroinvasion of SARS-CoV-2 in human and mouse brain.

Although COVID-19 is considered to be primarily a respiratory disease, SARS-CoV-2 affects multiple organ systems including the central nervous system (CNS). Yet, there is no consensus on the consequences of CNS infections. Here, we used three independent approaches to probe the capacity of SARS-CoV-2 to infect the brain.

Neuroinvasion of SARS-CoV-2 in human and mouse brain.

Although COVID-19 is considered to be primarily a respiratory disease, SARS-CoV-2 affects multiple organ systems including the central nervous system (CNS). Yet, there is no consensus whether the virus can infect the brain, or what the consequences of CNS infection are. Here, we used three independent approaches to probe the capacity of SARS-CoV-2 to infect the brain.

In vitro Modeling of Prion Strain Tropism.

Prions are atypical infectious agents lacking genetic material. Yet, various strains have been isolated from animals and humans using experimental models. They are distinguished by the resulting pattern of disease, including the localization of PrPsc deposits and the spongiform changes they induce in the brain of affected individuals.

Experimental transfusion of variant CJD-infected blood reveals previously uncharacterised prion disorder in mice and macaque.

Exposure of human populations to bovine spongiform encephalopathy through contaminated food has resulted in <250 cases of variant Creutzfeldt-Jakob disease (vCJD). However, more than 99% of vCJD infections could have remained silent suggesting a long-term risk of secondary transmission particularly through blood. Here, we present experimental evidence that transfusion in mice and non-human primates of blood products from symptomatic and non-symptomatic infected donors induces not only vCJD, but also a different class of neurological impairments.

Region-specific protein misfolding cyclic amplification reproduces brain tropism of prion strains.

Human prion diseases such as Creutzfeldt-Jakob disease are transmissible brain proteinopathies, characterized by the accumulation of a misfolded isoform of the host cellular prion protein (PrP) in the brain. According to the prion model, prions are defined as proteinaceous infectious particles composed solely of this abnormal isoform of PrP (PrP). Even in the absence of genetic material, various prion strains can be propagated in experimental models.

Detection and partial discrimination of atypical and classical bovine spongiform encephalopathies in cattle and primates using real-time quaking-induced conversion assay.

The transmission of classical bovine spongiform encephalopathy (C-BSE) through contaminated meat product consumption is responsible for variant Creutzfeldt-Jakob disease (vCJD) in humans. More recent and atypical forms of BSE (L-BSE and H-BSE) have been identified in cattle since the C-BSE epidemic. Their low incidence and advanced age of onset are compatible with a sporadic origin, as are most cases of Creutzfeldt-Jakob disease (CJD) in humans.

Molecular modeling of prion transmission to humans.

Using different prion strains, such as the variant Creutzfeldt-Jakob disease agent and the atypical bovine spongiform encephalopathy agents, and using transgenic mice expressing human or bovine prion protein, we assessed the reliability of protein misfolding cyclic amplification (PMCA) to model interspecies and genetic barriers to prion transmission. We compared our PMCA results with in vivo transmission data characterized by attack rates, i.e.

Cycline efficacy on the propagation of human prions in primary cultured neurons is strain-specific.

In prion diseases, a major issue in therapeutic research is the variability of the effect between strains. Stimulated by the report of an antiprion effect in a scrapie model and by ongoing international clinical trials using doxycycline, we studied the efficacy of cyclines against the propagation of human prions. First, we successfully propagated various Creutzfeldt-Jakob disease (CJD) isolates (sporadic, variant, and iatrogenic CJD) in neuronal cultures expressing the human prion protein.

Prion propagation and toxicity occur in vitro with two-phase kinetics specific to strain and neuronal type.

Prion diseases, or transmissible spongiform encephalopathies (TSEs), are fatal neurodegenerative disorders that occur in humans and animals. The neuropathological hallmarks of TSEs are spongiosis, glial proliferation, and neuronal loss. The only known specific molecular marker of TSEs is the abnormal isoform (PrP(Sc)) of the host-encoded prion protein (PrP(C)), which accumulates in the brain of infected subjects and forms infectious prion particles.

Substitutions at residue 211 in the prion protein drive a switch between CJD and GSS syndrome, a new mechanism governing inherited neurodegenerative disorders.

Human prion diseases are a heterogeneous group of fatal neurodegenerative disorders, characterized by the deposition of the partially protease-resistant prion protein (PrP(res)), astrocytosis, neuronal loss and spongiform change in the brain. Among inherited forms that represent 15% of patients, different phenotypes have been described depending on the variations detected at different positions within the prion protein gene. Here, we report a new mechanism governing the phenotypic variability of inherited prion diseases.

Variant Creutzfeldt-Jakob disease in France and the United Kingdom: Evidence for the same agent strain.

Objective: Variant Creutzfeldt-Jakob disease (vCJD) was first reported in the United Kingdom in 1996. Since then, the majority of cases have been observed in the United Kingdom where there was a major epidemic of bovine spongiform encephalopathy. France was the second country affected.

Regulating factors of PrP glycosylation in Creutzfeldt-Jakob disease--implications for the dissemination and the diagnosis of human prion strains.

Objective: The glycoprofile of pathological prion protein (PrP(res)) is widely used as a diagnosis marker in Creutzfeldt-Jakob disease (CJD) and is thought to vary in a strain-specific manner. However, that the same glycoprofile of PrP(res) always accumulates in the whole brain of one individual has been questioned. We aimed to determine whether and how PrP(res) glycosylation is regulated in the brain of patients with sporadic and variant Creutzfeldt-Jakob disease.

Experimental scrapie in 'plt' mice: an assessment of the role of dendritic-cell migration in the pathogenesis of prion diseases.

Peripherally acquired transmissible spongiform encephalopathies display strikingly long incubation periods, during which increasing amounts of prions can be detected in lymphoid tissues. While precise sites of peripheral accumulation have been described, the mechanisms of prion transport from mucosa and skin to lymphoid and nervous tissues remain unknown. Because of unique functional abilities, dendritic cells (DCs) have been suspected to participate in prion pathogenesis.

Oral scrapie infection modifies the homeostasis of Peyer's patches' dendritic cells.

In transmitted prion diseases the immune system supports the replication and the propagation of the pathogenic agent (PrPSc). DCs, which are mobile cells present in large numbers within lymph organs, are suspected to carry prions through the lymphoid system and to transfer them towards the peripheral nervous system. In this study, C57Bl/6 mice were orally inoculated with PrPSc (scrapie strain 139A) and sacrificed at the preclinical stages of the disease.

Potential role of microglia in retinal blood vessel formation.

Purpose: The role of microglia, present in the retina early in development before vascularization, remains ill defined. The authors investigated whether microglia are implicated in retinal blood vessel formation.

Methods: The microglia and vasculature of developing human fetal and rodent retinas were examined by labeling the endothelial cells with lectin and the microglia with CD18 antibody or green fluorescent protein driven by the promoter of the chemokine receptor CX(3)CR1.

Functional implication of cellular prion protein in antigen-driven interactions between T cells and dendritic cells.

The cellular prion protein (PrPC) is a host-encoded, GPI-anchored cell surface protein, expressed on a wide range of tissues including neuronal and lymphoreticular cells. PrPC may undergo posttranslational conversion, giving rise to scrapie PrP, the pathogenic conformer considered as responsible for prion diseases. Despite intensive studies, the normal function of PrPC is still enigmatic.

High resolution fundus imaging by confocal scanning laser ophthalmoscopy in the mouse.

We evaluated fundus imaging using a modified confocal scanning laser ophthalmoscope (cSLO) in mice. Examinations were performed in conscious, untrained mice. The largest field of view measured 1,520 x 1,520 mu, with a significant interindividual variability, itself correlated to biometric variability.

Astrocytes accumulate 4-hydroxynonenal adducts in murine scrapie and human Creutzfeldt-Jakob disease.

Scrapie-infected mice are considered a model for study in prion diseases, which are characterized by the progressive accumulation in the brain of an abnormal isoform (PrPsc) of the normal cellular prion protein (PrPc). Increasing data suggest that the neurodegenerative process in prion diseases may result, at least partially, from a defect in antioxidant function, but so far in vivo oxidative stress remains poorly documented. We report here that 4-hydroxynonenal, a lipid peroxidation by-product, forms protein adducts in brains of scrapie-infected mice and of Creutzfeldt-Jakob disease affected patients.

Phenotyping of protein-prion (PrPsc)-accumulating cells in lymphoid and neural tissues of naturally scrapie-affected sheep by double-labeling immunohistochemistry.

Transmissible spongiform encephalopathies are fatal neurodegenerative diseases characterized by amyloid deposition of protein-prion (PrPsc), the pathogenic isoform of the host cellular protein PrPc, in the immune and central nervous systems. In the absence of definitive data on the nature of the infectious agent, PrPsc immunohistochemistry (IHC) constitutes one of the main methodologies for pathogenesis studies of these diseases. In situ PrPsc immunolabeling requires formalin fixation and paraffin embedding of tissues, followed by post-embedding antigen retrieval steps such as formic acid and hydrated autoclaving treatments.