Classical BSE dismissed as the cause of CWD in Norwegian red deer despite strain similarities between both prion agents

The first case of CWD in a Norwegian red deer was detected by a routine ELISA test and confirmed by western blotting and immunohistochemistry in the brain stem of the animal. Two different western blotting tests were conducted independently in two different laboratories, showing that the red deer glycoprofile was different from the Norwegian CWD reindeer and CWD moose and from North American CWD. The isolate showed nevertheless features similar to the classical BSE (BSE-C) strain. Furthermore, BSE-C could not be excluded based on the PrPSc immunohistochemistry staining in the brainstem and the absence of detectable PrPSc in the lymphoid tissues. Because of the known ability of BSE-C to cross species barriers as well as its zoonotic potential, the CWD red deer isolate was submitted to the EURL Strain Typing Expert Group (STEG) as a BSE-C suspect for further investigation. In addition, different strain typing in vivo and in vitro strategies aiming at identifying the BSE-C strain in the red deer isolate were performed independently in three research groups and BSE-C was not found in it. These results suggest that the Norwegian CWD red deer case was infected with a previously unknown CWD type and further investigation is needed to determine the characteristics of this potential new CWD strain.

A Protein Misfolding Shaking Amplification-based method for the spontaneous generation of hundreds of bona fide prions

Prion diseases are a group of rapidly progressing neurodegenerative disorders caused by the misfolding of the endogenous prion protein (PrPC) into a pathogenic form (PrPSc). This process, despite being the central event underlying these disorders, remains largely unknown at a molecular level, precluding the prediction of new potential outbreaks or interspecies transmission incidents. In this work, we present a method to generate bona fide recombinant prions de novo, allowing a comprehensive analysis of protein misfolding across a wide range of prion proteins from mammalian species. We study more than 380 different prion proteins from mammals and classify them according to their spontaneous misfolding propensity and their conformational variability. This study aims to address fundamental questions in the prion research field such as defining infectivity determinants, interspecies transmission barriers or the structural influence of specific amino acids and provide invaluable information for future diagnosis and therapy applications.

Erratum: A tetracationic porphyrin with dual anti-prion activity

[This corrects the article DOI: 10.1016/j.isci.2023.107480.].

A tetracationic porphyrin with dual anti-prion activity

Prions are deadly infectious agents made of PrPSc, a misfolded variant of the cellular prion protein (PrPC) which self-propagates by inducing misfolding of native PrPC. PrPSc can adopt different pathogenic conformations (prion strains), which can be resistant to potential drugs, or acquire drug resistance, hampering the development of effective therapies. We identified Zn(II)-BnPyP, a tetracationic porphyrin that binds to distinct domains of native PrPC, eliciting a dual anti-prion effect. Zn(II)-BnPyP binding to a C-terminal pocket destabilizes the native PrPC fold, hindering conversion to PrPSc; Zn(II)-BnPyP binding to the flexible N-terminal tail disrupts N- to C-terminal interactions, triggering PrPC endocytosis and lysosomal degradation, thus reducing the substrate for PrPSc generation. Zn(II)-BnPyP inhibits propagation of different prion strains in vitro, in neuronal cells and organotypic brain cultures. These results identify a PrPC-targeting compound with an unprecedented dual mechanism of action which might be exploited to achieve anti-prion effects without engendering drug resistance.

Understanding the key features of the spontaneous formation of bona fide prions through a novel methodology that enables their swift and consistent generation

Among transmissible spongiform encephalopathies or prion diseases affecting humans, sporadic forms such as sporadic Creutzfeldt-Jakob disease are the vast majority. Unlike genetic or acquired forms of the disease, these idiopathic forms occur seemingly due to a random event of spontaneous misfolding of the cellular PrP (PrPC) into the pathogenic isoform (PrPSc). Currently, the molecular mechanisms that trigger and drive this event, which occurs in approximately one individual per million each year, remain completely unknown. Modelling this phenomenon in experimental settings is highly challenging due to its sporadic and rare occurrence. Previous attempts to model spontaneous prion misfolding in vitro have not been fully successful, as the spontaneous formation of prions is infrequent and stochastic, hindering the systematic study of the phenomenon. In this study, we present the first method that consistently induces spontaneous misfolding of recombinant PrP into bona fide prions within hours, providing unprecedented possibilities to investigate the mechanisms underlying sporadic prionopathies. By fine-tuning the Protein Misfolding Shaking Amplification method, which was initially developed to propagate recombinant prions, we have created a methodology that consistently produces spontaneously misfolded recombinant prions in 100% of the cases. Furthermore, this method gives rise to distinct strains and reveals the critical influence of charged surfaces in this process.

Analysis of a large case series of fatal familial insomnia to determine tests with the highest diagnostic value

Fatal familial insomnia (FFI) is a rare prionopathy with unusually high incidence in the Basque Country. We report detailed data on clinical, diagnostic, histopathological, and biochemical characteristics of a recent FFI case series. The Basque Brain Bank database was screened for patients diagnosed from 2010 to 2021 with standard genetic and/or neuropathological criteria. This series includes 16 patients, 25% without family history, with 12 cases from 9 unrelated (but geographically-linked, Basque country) kindreds, onset ranging from 36 to 70 years, and disease course from 7 to 11.5 months. Insomnia was the initial symptom in most cases, with consistent polysomnography in 92% of the cases. In contrast, 14-3-3 and RT-QuIC from cerebrospinal fluid were negative. Most patients were homozygous for methionine. Gliosis and neuronal loss in basal ganglia and thalamus were the main histopathological findings; Western blotting identified preferentially the protease-resistant prion protein (PrPres) type 2, although detection of the scrapie isoform of the prion protein (PrPSc) identified using brain tissue RT-QuIC was more successful. This is one of the largest current studies on FFI patients performed to provide improvements in diagnostic reliability. Among the analyzed tests, polysomnography and the genetic study show the highest diagnostic value in FFI.

Bona fide atypical scrapie faithfully reproduced for the first time in a rodent model

Atypical Scrapie, which is not linked to epidemics, is assumed to be an idiopathic spontaneous prion disease in small ruminants. Therefore, its occurrence is unlikely to be controlled through selective breeding or other strategies as it is done for classical scrapie outbreaks. Its spontaneous nature and its sporadic incidence worldwide is reminiscent of the incidence of idiopathic spontaneous prion diseases in humans, which account for more than 85% of the cases in humans. Hence, developing animal models that consistently reproduce this phenomenon of spontaneous PrP misfolding, is of importance to study the pathobiology of idiopathic spontaneous prion disorders. Transgenic mice overexpressing sheep PrP^C with I112 polymorphism (TgShI112, 1-2 × PrP levels compared to sheep brain) manifest clinical signs of a spongiform encephalopathy spontaneously as early as 380 days of age. The brains of these animals show the neuropathological hallmarks of prion disease and biochemical analyses of the misfolded prion protein show a ladder-like PrP^res pattern with a predominant 7-10 kDa band. Brain homogenates from spontaneously diseased transgenic mice were inoculated in several models to assess their transmissibility and characterize the prion strain generated: TgShI112 (ovine I112 ARQ PrP^C), Tg338 (ovine VRQ PrP^C), Tg501 (ovine ARQ PrP^C), Tg340 (human M129 PrP^C), Tg361 (human V129 PrP^C), TgVole (bank vole I109 PrP^C), bank vole (I109I PrP^C), and sheep (AHQ/ARR and AHQ/AHQ churra-tensina breeds). Our analysis of the results of these bioassays concludes that the strain generated in this model is indistinguishable to that causing atypical scrapie (Nor98). Thus, we present the first faithful model for a bona fide, transmissible, ovine, atypical scrapie prion disease.

Glycans are not necessary to maintain the pathobiological features of bovine spongiform encephalopathy

The role of the glycosylation status of PrPC in the conversion to its pathological counterpart and on cross-species transmission of prion strains has been widely discussed. Here, we assessed the effect on strain characteristics of bovine spongiform encephalopathy (BSE) isolates with different transmission histories upon propagation on a model expressing a non-glycosylated human PrPC. Bovine, ovine and porcine-passaged BSE, and variant Creutzfeldt-Jakob disease (vCJD) isolates were used as seeds/inocula in both in vitro and in vivo propagation assays using the non-glycosylated human PrPC-expressing mouse model (TgNN6h). After protein misfolding cyclic amplification (PMCA), all isolates maintained the biochemical characteristics of BSE. On bioassay, all PMCA-propagated BSE prions were readily transmitted to TgNN6h mice, in agreement with our previous in vitro results. TgNN6h mice reproduced the characteristic neuropathological and biochemical hallmarks of BSE, suggesting that the absence of glycans did not alter the pathobiological features of BSE prions. Moreover, back-passage of TgNN6h-adapted BSE prions to BoTg110 mice recovered the full BSE phenotype, confirming that the glycosylation of human PrPC is not essential for the preservation of the human transmission barrier for BSE prions or for the maintenance of BSE strain properties.

Description of the first Spanish case of Gerstmann-Sträussler-Scheinker disease with A117V variant: clinical, histopathological and biochemical characterization

Gerstmann–Sträussler–Scheinker disease (GSS) is a rare neurodegenerative illness that belongs to the group of hereditary or familial Transmissible Spongiform Encephalopathies (TSE). Due to the presence of different pathogenic alterations in the prion protein (PrP) coding gene, it shows an enhanced proneness to misfolding into its pathogenic isoform, leading to prion formation and propagation. This aberrantly folded protein is able to induce its conformation to the native counterparts forming amyloid fibrils and plaques partially resistant to protease degradation and showing neurotoxic properties. PrP with A117V pathogenic variant is the second most common genetic alteration leading to GSS and despite common phenotypic and neuropathological traits can be defined for each specific variant, strikingly heterogeneous manifestations have been reported for inter-familial cases bearing the same pathogenic variant or even within the same family. Given the scarcity of cases and their clinical, neuropathological, and biochemical variability, it is important to characterize thoroughly each reported case to establish potential correlations between clinical, neuropathological and biochemical hallmarks that could help to define disease subtypes. With that purpose in mind, this manuscript aims to provide a detailed report of the first Spanish GSS case associated with A117V variant including clinical, genetic, neuropathological and biochemical data, which could help define in the future potential disease subtypes and thus, explain the high heterogeneity observed in patients suffering from these maladies.

Homozygous R136S mutation in PRNP gene causes inherited early onset prion disease

BACKGROUND

More than 40 pathogenic heterozygous PRNP mutations causing inherited prion diseases have been identified to date. Recessive inherited prion disease has not been described to date.

METHODS

We describe the clinical and neuropathological data of inherited early-onset prion disease caused by the rare PRNP homozygous mutation R136S. In vitro PrPSc propagation studies were performed using recombinant-adapted protein misfolding cyclic amplification technique. Brain material from two R136S homozygous patients was intracranially inoculated in TgMet129 and TgVal129 transgenic mice to assess the transmissibility of this rare inherited form of prion disease.

RESULTS

The index case presented symptoms of early-onset dementia beginning at the age of 49 and died at the age of 53. Neuropathological evaluation of the proband revealed abundant multicentric PrP plaques and Western blotting revealed a ~ 8 kDa protease-resistant, unglycosylated PrPSc fragment, consistent with a Gerstmann-Sträussler-Scheinker phenotype. Her youngest sibling suffered from progressive cognitive decline, motor impairment, and myoclonus with onset in her late 30s and died at the age of 48. Genetic analysis revealed the presence of the R136S mutation in homozygosis in the two affected subjects linked to homozygous methionine at codon 129. One sibling carrying the heterozygous R136S mutation, linked to homozygous methionine at codon 129, is still asymptomatic at the age of 74. The inoculation of human brain homogenates from our index case and an independent case from a Portuguese family with the same mutation in transgenic mice expressing human PrP and in vitro propagation of PrPSc studies failed to show disease transmissibility.

CONCLUSION

In conclusion, biallelic R136S substitution is a rare variant that produces inherited early-onset human prion disease with a Gerstmann-Sträussler-Scheinker neuropathological and molecular signature. Even if the R136S variant is predicted to be "probably damaging", heterozygous carriers are protected, at least from an early onset providing evidence for a potentially recessive pattern of inheritance in human prion diseases.

Biosemiotics comprehension of PrP code and prion disease

Prions or PrP^Sc (prion protein, Scrapie isoform) are proteins with an aberrant three-dimensional conformation that present the ability to alter the three-dimensional structure of natively folded PrP^C (prion protein, cellular isoform) inducing its abnormal folding, giving raise to neurological diseases known as Transmissible spongiforms encephalopathies (TSEs) or prion diseases. In this work, through a biosemiotic study, we will analyze the molecular code of meanings that are known in the molecular pathway of PrP^C and how it is altered in prion diseases. This biosemiotic code presents a socio-semiotic correlate in organisms that could be unraveled with the ultimate goal of understanding the code of signs that mediates the process. Finally, we will study recent works that indicate possible relationships in the code between prion proteins and other proteins such as the tau protein and alpha-synuclein to evaluate if it is possible that there is a semiotic expansion of the PrP code and prion diseases in the meaning recently expounded by Prusiner, winner of the Nobel Prize for describing these unusual pathological processes.

Sporadic Creutzfeldt-Jakob disease with extremely long 14-year survival period

Background and purpose

Sporadic Creutzfeldt–Jakob disease is a rapidly progressing and highly variable neurodegenerative disease with heterogeneous clinical presentation and a median survival time from diagnosis to death of 4–6 months.

Methods

We report a rare case of a 61‐year‐old woman with a history of initially rapidly progressive dementia, with subsequent development of pyramidal and extrapyramidal signs and with an unusually long survival period of 14 years. Initial magnetic resonance imaging evaluation, single‐photon emission computed tomography, and electroencephalogram did not show relevant alterations.

Results

The postmortem examination of the brain showed diffuse spongiform change, gliosis, and neuronal loss along with abnormal immunostaining of prion protein in the grey matter, especially in the cerebellum. Indirect PRNP genetic analysis was negative.

Conclusions

This case is, to our knowledge, the sporadic Creutzfeldt–Jakob disease patient with the longest survival period ever documented. This surprisingly long duration highlights the importance of histopathological confirmation with brain autopsies for suspected cases, as the disease can easily be misdiagnosed in such slowly progressing cases.

[First wave of the COVID-19 pandemic in Navarre, Spain, February-June 2020]

BACKGROUND

The COVID-19 pandemic was declared in 2020. The shortage of diagnostic tests limited monitoring of the first wave of the pandemic. This study estimates and describes the wave in Navarre (Spain).

METHODS

Enhanced epidemiological surveillance, seroepidemiological survey estimates and mortality registries were used to characterise the first wave of the COVID-19 pandemic from February to June 2020 in Navarre.

RESULTS

A total of 10,358 persons (1.6?% of population) were confirmed with COVID-19, 1,943 cases were hospitalized (3 per 1,000 inhabitants), 139 were admitted to the ICU (21 per 100,000 inhabitants), and 529 people died from confirmed COVID-19 (80 per 100,000). Mortality increased exponentially with age, exceeding 1?% in people over 85 years. 58?% of deaths occurred amongst nursing home residents. The mortality registry received reporting of 733 confirmed or probable COVID-19 deaths, while the excess deaths during this period were 613 (20.9?%) concentrated from mid-March to the end of April. It is estimated that, at the end of June, 6.7?% (n?=?44,000) of the population had detectable antibodies against SARS-CoV-2 and 10.3?% had had the infection. The estimates of SARS-CoV-2 infection incidence increased sharply in the first half of March and decreased quickly during the home lockdown in the second half of March.

CONCLUSIONS

The first wave of the pandemic produced a high number of cases, hospitalizations and deaths in Navarre in a few weeks. The pronounced decrease of SARS-CoV-2 infections during the home lockdown suggests considerable efficacy and impact of this measure for transmission control.

Detection of chronic wasting disease in mule and white-tailed deer by RT-QuIC analysis of outer ear

Efforts to contain the spread of chronic wasting disease (CWD), a fatal, contagious prion disease of cervids, would be aided by the availability of additional diagnostic tools. RT-QuIC assays allow ultrasensitive detection of prion seeds in a wide variety of cervid tissues, fluids and excreta. The best documented antemortem diagnostic test involving RT-QuIC analysis targets lymphoid tissue in rectal biopsies. Here we have tested a more easily accessed specimen, ear pinna punches, using an improved RT-QuIC assay involving iron oxide magnetic extraction to detect CWD infections in asymptomatic mule and white-tailed deer. Comparison of multiple parts of the ear pinna indicated that a central punch spanning the auricular nerve provided the most consistent detection of CWD infection. When compared to results obtained from gold-standard retropharyngeal lymph node specimens, our RT-QuIC analyses of ear samples provided apparent diagnostic sensitivity (81%) and specificity (91%) that rivaled, or improved upon, those observed in previous analyses of rectal biopsies using RT-QuIC. These results provide evidence that RT-QuIC analysis of ear pinna punches may be a useful approach to detecting CWD infections in cervids.

Prion-Associated Neurodegeneration Causes Both Endoplasmic Reticulum Stress and Proteasome Impairment in a Murine Model of Spontaneous Disease

Prion diseases are a group of neurodegenerative disorders that can be spontaneous, familial or acquired by infection. The conversion of the prion protein PrP^C to its abnormal and misfolded isoform PrP^Sc is the main event in the pathogenesis of prion diseases of all origins. In spontaneous prion diseases, the mechanisms that trigger the formation of PrP^Sc in the central nervous system remain unknown. Several reports have demonstrated that the accumulation of PrP^Sc can induce endoplasmic reticulum (ER) stress and proteasome impairment from the early stages of the prion disease. Both mechanisms lead to an increment of PrP aggregates in the secretory pathway, which could explain the pathogenesis of spontaneous prion diseases. Here, we investigate the role of ER stress and proteasome impairment during prion disorders in a murine model of spontaneous prion disease (TgVole) co-expressing the Ub^G76V-GFP reporter, which allows measuring the proteasome activity in vivo. Spontaneously prion-affected mice showed a significantly higher accumulation of the PKR-like ER kinase (PERK), the ER chaperone binding immunoglobulin protein (BiP/Grp78), the ER protein disulfide isomerase (PDI) and the Ub^G76V-GFP reporter than age-matched controls in certain brain areas. The upregulation of PERK, BiP, PDI and ubiquitin was detected from the preclinical stage of the disease, indicating that ER stress and proteasome impairment begin at early stages of the spontaneous disease. Strong correlations were found between the deposition of these markers and neuropathological markers of prion disease in both preclinical and clinical mice. Our results suggest that both ER stress and proteasome impairment occur during the pathogenesis of spontaneous prion diseases.

Evaluation of the Influence of Astrocytes on In Vitro Blood-Brain Barrier Models

In vitro blood-brain barrier (BBB) models are a useful tool to screen the permeability and toxicity of new drugs. Currently, many different in vitro BBB models coexist, but none stands out as being notably better than the rest. Therefore, there is still a need to evaluate the quality of BBB models under various conditions and assess their ability to mimic the in vivo situation. In this study, two brain endothelial cell lines (bEnd.3 and hCMEC/D3) and two epithelial-like cell lines (MDCKII and Caco-2) were selected for BBB modelling purposes. They were grown as monolayers of a single cell type, under the following conditions: in coculture with either primary or immortalised astrocytes; or in the presence of primary or immortalised astrocyte-derived conditioned media. A total of 20 different BBB models were established in this manner, in order to assess the effects of the astroglial components on the BBB phenotype in each case. To this end, six parameters were studied: the expression of selected tight junction proteins; the enzyme activities of alkaline phosphatase and of gamma glutamyl transpeptidase; the transendothelial/transepithelial electrical resistance (TEER); restriction in paracellular transport; and efflux transporter inhibition were each evaluated and correlated. The results showed that coculturing with either primary or immortalised astrocytes led to a general improvement in all parameters studied, evidencing the contribution of this cell type to effective BBB formation. Furthermore, the permeability coefficient (P _e) of the tracer molecule, Lucifer Yellow, correlated with three of the six parameters studied. In addition, this study highlights the potential for the use of the Lucifer Yellow P _e value as an indicator of barrier integrity in in vitro BBB models, which could be useful for screening the permeability of new drugs.

A Novel, Reliable and Highly Versatile Method to Evaluate Different Prion Decontamination Procedures

Transmissible spongiform encephalopathies (TSEs) are a group of invariably fatal neurodegenerative disorders. The causal agent is an aberrantly folded isoform (PrP^Sc or prion) of the endogenous prion protein (PrP^C) which is neurotoxic and amyloidogenic and induces misfolding of its physiological counterpart. The intrinsic physical characteristics of these infectious proteinaceous pathogens makes them highly resistant to the vast majority of physicochemical decontamination procedures used typically for standard disinfection. This means prions are highly persistent in contaminated tissues, the environment (surfaces) and, of great concern, on medical and surgical instruments. Traditionally, decontamination procedures for prions are tested on natural isolates coming from the brain of infected individuals with an associated high heterogeneity resulting in highly variable results. Using our novel ability to produce highly infectious recombinant prions in vitro we adapted the system to enable recovery of infectious prions from contaminated materials. This method is easy to perform and, importantly, results in highly reproducible propagation in vitro. It exploits the adherence of infectious prion protein to beads of different materials allowing accurate and repeatable assessment of the efficacy of disinfectants of differing physicochemical natures to eliminate infectious prions. This method is technically easy, requires only a small shaker and a standard biochemical technique and could be performed in any laboratory.

Autoantibodies against the prion protein in individuals with PRNP mutations

OBJECTIVE

To determine whether naturally occurring autoantibodies against the prion protein are present in individuals with genetic prion disease mutations and controls, and if so, whether they are protective against prion disease.

METHODS

In this case-control study, we collected 124 blood samples from individuals with a variety of pathogenic PRNP mutations and 78 control individuals with a positive family history of genetic prion disease but lacking disease-associated PRNP mutations. Antibody reactivity was measured using an indirect ELISA for the detection of human immunoglobulin G_1-4 antibodies against wild-type human prion protein. Multivariate linear regression models were constructed to analyze differences in autoantibody reactivity between (1) PRNP mutation carriers vs controls and (2) asymptomatic vs symptomatic PRNP mutation carriers. Robustness of results was examined in matched cohorts.

RESULTS

We found that antibody reactivity was present in a subset of both PRNP mutation carriers and controls. Autoantibody levels were not influenced by PRNP mutation status or clinical manifestation of prion disease. Post hoc analyses showed anti-PrP^C autoantibody titers to be independent of personal history of autoimmune disease and other immunologic disorders, as well as PRNP codon 129 polymorphism.

CONCLUSIONS

Pathogenic PRNP variants do not notably stimulate antibody-mediated anti-PrP^C immunity. Anti-PrP^C immunoglobulin G autoantibodies are not associated with the onset of prion disease. The presence of anti-PrP^C autoantibodies in the general population without any disease-specific association suggests that relatively high titers of naturally occurring antibodies are well-tolerated.

CLINICALTRIALSGOV IDENTIFIER

NCT02837705.

Dogs are resistant to prion infection, due to the presence of aspartic or glutamic acid at position 163 of their prion protein

Unlike other species, prion disease has never been described in dogs even though they were similarly exposed to the bovine spongiform encephalopathy (BSE) agent. This resistance prompted a thorough analysis of the canine PRNP gene and the presence of a negatively charged amino acid residue in position 163 was readily identified as potentially fundamental as it differed from all known susceptible species. In the present study, the first transgenic mouse model expressing dog prion protein (PrP) was generated and challenged intracerebrally with a panel of prion isolates, none of which could infect them. The brains of these mice were subjected to in vitro prion amplification and failed to find even minimal amounts of misfolded prions providing definitive experimental evidence that dogs are resistant to prion disease. Subsequently, a second transgenic model was generated in which aspartic acid in position 163 was substituted for asparagine (the most common in prion susceptible species) resulting in susceptibility to BSE-derived isolates. These findings strongly support the hypothesis that the amino acid residue at position 163 of canine cellular prion protein (PrP^C ) is a major determinant of the exceptional resistance of the canidae family to prion infection and establish this as a promising therapeutic target for prion diseases.

Development of a new largely scalable in vitro prion propagation method for the production of infectious recombinant prions for high resolution structural studies

The resolution of the three-dimensional structure of infectious prions at the atomic level is pivotal to understand the pathobiology of Transmissible Spongiform Encephalopathies (TSE), but has been long hindered due to certain particularities of these proteinaceous pathogens. Difficulties related to their purification from brain homogenates of disease-affected animals were resolved almost a decade ago by the development of in vitro recombinant prion propagation systems giving rise to highly infectious recombinant prions. However, lack of knowledge about the molecular mechanisms of the misfolding event and the complexity of systems such as the Protein Misfolding Cyclic Amplification (PMCA), have limited generating the large amounts of homogeneous recombinant prion preparations required for high-resolution techniques such as solid state Nuclear Magnetic Resonance (ssNMR) imaging. Herein, we present a novel recombinant prion propagation system based on PMCA that substitutes sonication with shaking thereby allowing the production of unprecedented amounts of multi-labeled, infectious recombinant prions. The use of specific cofactors, such as dextran sulfate, limit the structural heterogeneity of the in vitro propagated prions and makes possible, for the first time, the generation of infectious and likely homogeneous samples in sufficient quantities for studies with high-resolution structural techniques as demonstrated by the preliminary ssNMR spectrum presented here. Overall, we consider that this new method named Protein Misfolding Shaking Amplification (PMSA), opens new avenues to finally elucidate the three-dimensional structure of infectious prions.

Repurposing ciclopirox as a pharmacological chaperone in a model of congenital erythropoietic porphyria

Congenital erythropoietic porphyria is a rare autosomal recessive disease produced by deficient activity of uroporphyrinogen III synthase, the fourth enzyme in the heme biosynthetic pathway. The disease affects many organs, can be life-threatening, and currently lacks curative treatments. Inherited mutations most commonly reduce the enzyme's stability, altering its homeostasis and ultimately blunting intracellular heme production. This results in uroporphyrin by-product accumulation in the body, aggravating associated pathological symptoms such as skin photosensitivity and disfiguring phototoxic cutaneous lesions. We demonstrated that the synthetic marketed antifungal ciclopirox binds to the enzyme, stabilizing it. Ciclopirox targeted the enzyme at an allosteric site distant from the active center and did not affect the enzyme's catalytic role. The drug restored enzymatic activity in vitro and ex vivo and was able to alleviate most clinical symptoms of congenital erythropoietic porphyria in a genetic mouse model of the disease at subtoxic concentrations. Our findings establish a possible line of therapeutic intervention against congenital erythropoietic porphyria, which is potentially applicable to most of deleterious missense mutations causing this devastating disease.

[Qualitative analysis of the social and family impact of human transmissible spongiform encephalopathies]

INTRODUCTION

Human transmissible spongiform encephalopathies are pathologies related to the misfolding of the cellular prion protein. When these diseases manifest, they are characterized by a rapid and invariably fatal neurodegeneration.

AIM

To gain insight on the social, personal and family reality of the people in close contact with these disorders.

PATIENTS AND METHODS

Qualitative interviews were conducted online through semi-structured questionnaires open to carriers and first-degree relatives of those affected. The information was anonymous and the responses were requested to be broad.

RESULTS

The sample consisted on 47 interviewees, seven confirmed carriers and 40 relatives that might be carriers or not. The majority of the informants were women aged between 30 and 50. The discourse analysis focused on their perception of the disease, time to diagnosis, and their uncertainties/needs allowed establishing four semantic fields: suffering/loss, temporality, medical/clinical and daily life. However, other important elements were also found. Only eight relatives considered necessary to increase research efforts. Relatives also presented a higher rate of uncertainty, while confirmed carriers did not show such uncertainty about their future.

CONCLUSIONS

Socio-biomedical studies related to prion pathologies are rare. In this work, our knowledge on the social reality of the affected people and their close relatives is extended. These pathologies lead those in close contact with them to extremely complicated social situations with utmost psychosocial management difficulties.

Insights into the Bidirectional Properties of the Sheep-Deer Prion Transmission Barrier

The large chronic wasting disease (CWD)-affected cervid population in the USA and Canada, and the risk of the disease being transmitted to humans through intermediate species, is a highly worrying issue that is still poorly understood. In this case, recombinant protein misfolding cyclic amplification was used to determine, in vitro, the relevance of each individual amino acid on cross-species prion transmission. Others and we have found that the β2-α2 loop is a key modulator of transmission barriers between species and markedly influences infection by sheep scrapie, bovine spongiform encephalopathy (BSE), or elk CWD. Amino acids that differentiate ovine and deer normal host prion protein (PrP^C) and associated with structural rigidity of the loop β2-α2 (S173N, N177T) appear to confer resistance to some prion diseases. However, addition of methionine at codon 208 together with the previously described rigid loop substitutions seems to hide a key in this species barrier, as it makes sheep recombinant prion protein highly susceptible to CWD-induced misfolding. These studies indicate that interspecies prion transmission is not only governed just by the β2-α2 loop amino acid sequence but also by its interactions with the α3-helix as shown by substitution I208M. Transmissible spongiform encephalopathies, characterized by long incubation periods and spongiform changes associated with neuronal loss in the brain, have been described in several mammalian species appearing either naturally (scrapie in sheep and goats, bovine spongiform encephalopathy in cattle, chronic wasting disease in cervids, Creutzfeldt-Jakob disease in humans) or by experimental transmission studies (scrapie in mice and hamsters). Much of the pathogenesis of the prion diseases has been determined in the last 40 years, such as the etiological agent or the fact that prions occur as different strains that show distinct biological and physicochemical properties. However, there are many unanswered questions regarding the strain phenomenon and interspecies transmissibility. To assess the risk of interspecies transmission between scrapie and chronic wasting disease, an in vitro prion propagation method has been used. This technique allows to predict the amino acids preventing the transmission between sheep and deer prion diseases.

Compositional analysis of dietary patterns

Instead of looking at individual nutrients or foods, dietary pattern analysis has emerged as a promising approach to examine the relationship between diet and health outcomes. Despite dietary patterns being compositional (i.e. usually a higher intake of some foods implies that less of other foods are being consumed), compositional data analysis has not yet been applied in this setting. We describe three compositional data analysis approaches (compositional principal component analysis, balances and principal balances) that enable the extraction of dietary patterns by using control subjects from the Spanish multicase-control (MCC-Spain) study. In particular, principal balances overcome the limitations of purely data-driven or investigator-driven methods and present dietary patterns as trade-offs between eating more of some foods and less of others.

A Quick Method to Evaluate the Effect of the Amino Acid Sequence in the Misfolding Proneness of the Prion Protein

Prion diseases or transmissible spongiform encephalopathies (TSEs) are a group of neurodegenerative diseases where the misfolding of the prion protein (PrP) is a crucial event. Based on studies in TSE-affected humans and the generation of transgenic mouse models overexpressing different mutated versions of the PrP, we conclude that both wild-type and mutated PrPs exhibit differential propensity to misfold in vivo. Here, we describe a new method in vitro to assess and quantify the PrP misfolding phenomenon in order to better understand the molecular mechanisms involved in this process.

iPS Cell Cultures from a Gerstmann-Sträussler-Scheinker Patient with the Y218N PRNP Mutation Recapitulate tau Pathology

Gerstmann-Sträussler-Scheinker (GSS) syndrome is a fatal autosomal dominant neurodegenerative prionopathy clinically characterized by ataxia, spastic paraparesis, extrapyramidal signs and dementia. In some GSS familiar cases carrying point mutations in the PRNP gene, patients also showed comorbid tauopathy leading to mixed pathologies. In this study we developed an induced pluripotent stem (iPS) cell model derived from fibroblasts of a GSS patient harboring the Y218N PRNP mutation, as well as an age-matched healthy control. This particular PRNP mutation is unique with very few described cases. One of the cases presented neurofibrillary degeneration with relevant Tau hyperphosphorylation. Y218N iPS-derived cultures showed relevant astrogliosis, increased phospho-Tau, altered microtubule-associated transport and cell death. However, they failed to generate proteinase K-resistant prion. In this study we set out to test, for the first time, whether iPS cell-derived neurons could be used to investigate the appearance of disease-related phenotypes (i.e, tauopathy) identified in the GSS patient.

Behind the potential evolution towards prion resistant species

Historically, the observation of naturally occurring cases of prion disease led to the classification of different susceptibility grades and to the designation of prion resistant species. However, the development of highly efficient in vitro prion propagation systems and the generation of ad hoc transgenic models allowed determining that leporidae and equidae families have been erroneously considered resistant to prion infection. On the contrary, similar approaches revealed an unexpected high level of resistance of the canidae family. In PLoS Pathogens [ 1 ], we describe experiments directed toward elucidating which are the determinants of the alleged prion resistance of this family. Studies based on the sequence of the canine prion protein coupled with structural in silico analysis identified a key residue probably implicated in this resistance. Cell and brain-based PMCA highlighted that the presence of aspartic or glutamic acid at codon 163 of the canid PrP, strongly inhibits prion replication in vitro. Transgenic animals carrying this substitution in mouse PrP were resistant to prion infection after intracerebral challenge with different mouse prion strains. The confirmation of the importance of this substitution and its exclusivity in this family, suggests it could have been evolutionarily favored, due to their diet based on carrion and small ruminants.

Recombinant PrPSc shares structural features with brain-derived PrPSc: Insights from limited proteolysis

Very solid evidence suggests that the core of full length PrPSc is a 4-rung β-solenoid, and that individual PrPSc subunits stack to form amyloid fibers. We recently used limited proteolysis to map the β-strands and connecting loops that make up the PrPSc solenoid. Using high resolution SDS-PAGE followed by epitope analysis, and mass spectrometry, we identified positions ~116/118, 133-134, 141, 152-153, 162, 169 and 179 (murine numbering) as Proteinase K (PK) cleavage sites in PrPSc. Such sites likely define loops and/or borders of β-strands, helping us to predict the threading of the β-solenoid. We have now extended this approach to recombinant PrPSc (recPrPSc). The term recPrPSc refers to bona fide recombinant prions prepared by PMCA, exhibiting infectivity with attack rates of ~100%. Limited proteolysis of mouse and bank vole recPrPSc species yielded N-terminally truncated PK-resistant fragments similar to those seen in brain-derived PrPSc, albeit with varying relative yields. Along with these fragments, doubly N- and C-terminally truncated fragments, in particular ~89/97-152, were detected in some recPrPSc preparations; similar fragments are characteristic of atypical strains of brain-derived PrPSc. Our results suggest a shared architecture of recPrPSc and brain PrPSc prions. The observed differences, in particular the distinct yields of specific PK-resistant fragments, are likely due to differences in threading which result in the specific biochemical characteristics of recPrPSc. Furthermore, recombinant PrPSc offers exciting opportunities for structural studies unachievable with brain-derived PrPSc.

An Amino Acid Substitution Found in Animals with Low Susceptibility to Prion Diseases Confers a Protective Dominant-Negative Effect in Prion-Infected Transgenic Mice

While prion diseases have been described in numerous species, some, including those of the Canidae family, appear to show resistance or reduced susceptibility. A better understanding of the factors underlying prion susceptibility is crucial for the development of effective treatment and control measures. We recently demonstrated resistance to prion infection in mice overexpressing a mutated prion protein (PrP) carrying a specific amino acid substitution characteristic of canids. Here, we show that coexpression of this mutated PrP and wild-type mouse PrP in transgenic mice inoculated with different mouse-adapted prion strains (22 L, ME7, RML, and 301C) significantly increases survival times (by 45 to 113%). These data indicate that this amino acid substitution confers a dominant-negative effect on PrP, attenuating the conversion of PrP^C to PrP^Sc and delaying disease onset without altering the neuropathological properties of the prion strains. Taken together, these findings have important implications for the development of new treatment approaches for prion diseases based on dominant-negative proteins.

Recombinant PrP and Its Contribution to Research on Transmissible Spongiform Encephalopathies

The misfolding of the cellular prion protein (PrPC) into the disease-associated isoform (PrPSc) and its accumulation as amyloid fibrils in the central nervous system is one of the central events in transmissible spongiform encephalopathies (TSEs). Due to the proteinaceous nature of the causal agent the molecular mechanisms of misfolding, interspecies transmission, neurotoxicity and strain phenomenon remain mostly ill-defined or unknown. Significant advances were made using in vivo and in cellula models, but the limitations of these, primarily due to their inherent complexity and the small amounts of PrPSc that can be obtained, gave rise to the necessity of new model systems. The production of recombinant PrP using E. coli and subsequent induction of misfolding to the aberrant isoform using different techniques paved the way for the development of cell-free systems that complement the previous models. The generation of the first infectious recombinant prion proteins with identical properties of brain-derived PrPSc increased the value of cell-free systems for research on TSEs. The versatility and ease of implementation of these models have made them invaluable for the study of the molecular mechanisms of prion formation and propagation, and have enabled improvements in diagnosis, high-throughput screening of putative anti-prion compounds and the design of novel therapeutic strategies. Here, we provide an overview of the resultant advances in the prion field due to the development of recombinant PrP and its use in cell-free systems.

Unraveling the key to the resistance of canids to prion diseases

One of the characteristics of prions is their ability to infect some species but not others and prion resistant species have been of special interest because of their potential in deciphering the determinants for susceptibility. Previously, we developed different in vitro and in vivo models to assess the susceptibility of species that were erroneously considered resistant to prion infection, such as members of the Leporidae and Equidae families. Here we undertake in vitro and in vivo approaches to understand the unresolved low prion susceptibility of canids. Studies based on the amino acid sequence of the canine prion protein (PrP), together with a structural analysis in silico, identified unique key amino acids whose characteristics could orchestrate its high resistance to prion disease. Cell- and brain-based PMCA studies were performed highlighting the relevance of the D163 amino acid in proneness to protein misfolding. This was also investigated by the generation of a novel transgenic mouse model carrying this substitution and these mice showed complete resistance to disease despite intracerebral challenge with three different mouse prion strains (RML, 22L and 301C) known to cause disease in wild-type mice. These findings suggest that dog D163 amino acid is primarily, if not totally, responsible for the prion resistance of canids.

Detection of individuals or whole species resistant to any infectious disease is vital to understand the determinants of susceptibility and to develop appropriate therapeutic and preventative strategies. Canids have long been considered resistant to prion infection given the absence of clinical disease despite exposure to the causal agent. Through extensive analysis of the canine prion protein we have detected a key amino acid that might be responsible for their universal resistance to prion disease. Using in vitro and in vivo models we demonstrated that the presence of this residue confers resistance to prion infection when introduced to susceptible animals, opening the way to develop a new therapeutic approach against these, at present, untreatable disorders.

Soluble polymorphic bank vole prion proteins induced by co-expression of quiescin sulfhydryl oxidase in E. coli and their aggregation behaviors

Background

The infectious prion protein (PrP^Sc or prion) is derived from its cellular form (PrP^C) through a conformational transition in animal and human prion diseases. Studies have shown that the interspecies conversion of PrP^C to PrP^Sc is largely swayed by species barriers, which is mainly deciphered by the sequence and conformation of the proteins among species. However, the bank vole PrP^C (BVPrP) is highly susceptible to PrP^Sc from different species. Transgenic mice expressing BVPrP with the polymorphic isoleucine (109I) but methionine (109M) at residue 109 spontaneously develop prion disease.

Results

To explore the mechanism underlying the unique susceptibility and convertibility, we generated soluble BVPrP by co-expression of BVPrP with Quiescin sulfhydryl oxidase (QSOX) in Escherichia coli. Interestingly, rBVPrP-109M and rBVPrP-109I exhibited distinct seeded aggregation pathways and aggregate morphologies upon seeding of mouse recombinant PrP fibrils, as monitored by thioflavin T fluorescence and electron microscopy. Moreover, they displayed different aggregation behaviors induced by seeding of hamster and mouse prion strains under real-time quaking-induced conversion.

Conclusions

Our results suggest that QSOX facilitates the formation of soluble prion protein and provide further evidence that the polymorphism at residue 109 of QSOX-induced BVPrP may be a determinant in mediating its distinct convertibility and susceptibility.

Cause of death in hospitalized patients with laboratory-confirmed influenza

BACKGROUND

We analyzed the underlying cause of death recorded in hospitalized patients with laboratory-confirmed influenza.

METHODS

The present study included all patients with a laboratory-confirmed diagnosis of influenza during the influenza seasons 2009-2010 to 2013-2014 who were attended to in hospital and died. Their underlying cause of death according to the International Classification of Diseases 10th Revision was obtained from the Navarre Mortality Registry.

RESULTS

Among 49 patients studied, the underlying causes of death were 35% influenza, 4% pneumonia, 14% other respiratory diseases, 10% circulatory disease and 37% other causes.

CONCLUSIONS

Non-cardiorespiratory causes accounted for a third of deaths in patients with confirmed influenza, thus all-cause mortality should be considered in estimating the full burden of influenza mortality.

Generation of a new infectious recombinant prion: a model to understand Gerstmann-Sträussler-Scheinker syndrome

Human transmissible spongiform encephalopathies (TSEs) or prion diseases are a group of fatal neurodegenerative disorders that include Kuru, Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker syndrome (GSS), and fatal familial insomnia. GSS is a genetically determined TSE caused by a range of mutations within the prion protein (PrP) gene. Several animal models, based on the expression of PrPs carrying mutations analogous to human heritable prion diseases, support that mutations might predispose PrP to spontaneously misfold. An adapted Protein Misfolding Cyclic Amplification methodology based on the use of human recombinant PrP (recPMCA) generated different self-propagating misfolded proteins spontaneously. These were characterized biochemically and structurally, and the one partially sharing some of the GSS PrP^Sc molecular features was inoculated into different animal models showing high infectivity. This constitutes an infectious recombinant prion which could be an invaluable model for understanding GSS. Moreover, this study proves the possibility to generate recombinant versions of other human prion diseases that could provide a further understanding on the molecular features of these devastating disorders.

An antipsychotic drug exerts anti-prion effects by altering the localization of the cellular prion protein

Prion diseases are neurodegenerative conditions characterized by the conformational conversion of the cellular prion protein (PrP^C), an endogenous membrane glycoprotein of uncertain function, into PrP^Sc, a pathological isoform that replicates by imposing its abnormal folding onto PrP^C molecules. A great deal of evidence supports the notion that PrP^C plays at least two roles in prion diseases, by acting as a substrate for PrP^Sc replication, and as a mediator of its toxicity. This conclusion was recently supported by data suggesting that PrP^C may transduce neurotoxic signals elicited by other disease-associated protein aggregates. Thus, PrP^C may represent a convenient pharmacological target for prion diseases, and possibly other neurodegenerative conditions. Here, we sought to characterize the activity of chlorpromazine (CPZ), an antipsychotic previously shown to inhibit prion replication by directly binding to PrP^C. By employing biochemical and biophysical techniques, we provide direct experimental evidence indicating that CPZ does not bind PrP^C at biologically relevant concentrations. Instead, the compound exerts anti-prion effects by inducing the relocalization of PrP^C from the plasma membrane. Consistent with these findings, CPZ also inhibits the cytotoxic effects delivered by a PrP mutant. Interestingly, we found that the different pharmacological effects of CPZ could be mimicked by two inhibitors of the GTPase activity of dynamins, a class of proteins involved in the scission of newly formed membrane vesicles, and recently reported as potential pharmacological targets of CPZ. Collectively, our results redefine the mechanism by which CPZ exerts anti-prion effects, and support a primary role for dynamins in the membrane recycling of PrP^C, as well as in the propagation of infectious prions.

[Effectiveness of second-generation direct-acting antivirals in chronic hepatitis C]

BACKGROUND

Second-generation direct-acting antivirals (DAA) have shown high sustained virologic response (SVR) for the treatment of chronic hepatitis C in clinical trials. The objective of this study is to estimate DAA effectiveness in treatment of this disease.

METHODS

Hepatitis C virus (HCV) monoinfected patients and HCV-human immunodeficiency virus (HIV) coinfected pa-tients who started interferon-free DAA based regimens during 2015 were included. The primary effectiveness outcome was SVR, defined as an undetectable viral load 12 weeks after the end of treatment.

RESULTS

A total of 293 patients were enrolled, and 52 (17.7%) were HIV coinfected. HCV 1b genotype was the most prevalent in monoinfected patients (41.5%) and 1a in HIV coinfected patients (40.4%). The proportion of cirrhosis was higher among HIV coinfected patients (69.2% vs 41.1%; p<0.0001), mostly Child-Pugh A. SVR was achieved by 96.9% of patients (284/293), in an intention-to-treat analysis (CI 95%: 94.9-98.9), in which just 4 people had virologic failure. Both naïve and pretreated patients had SVR higher than 95%, and in most of subgroups, according to the presence of cirrhosis, HIV coinfection and HVC genotype, effectiveness rates were near or above 90%.

CONCLUSIONS

DAA are highly effective, with similar or higher rates of SVR than that found in clinical trials, and even among difficult to treat populations.

Protein misfolding cyclic amplification corroborates the absence of PrPSc accumulation in placenta from foetuses with the ARR/ARQ genotype in natural scrapie

Ovine scrapie is a worldwide spread prion disease that is transmitted horizontally under field conditions. Placenta from scrapie-infected ewes is an important source of infection, since this tissue can accumulate high amounts of PrP^Sc depending on the foetal genotype. Therefore, placentas carrying susceptible foetuses can accumulate PrP^Sc but there is not PrP^Sc accumulation in presence of foetuses with at least one ARR haplotype. In scrapie eradication programs, ARR/ARR males are used for breeding to increase the resistant progeny and reduce the horizontal transmission of the disease through the placenta. The development of highly sensitive techniques, that allow the detection of minimal amounts of PrP^Sc, has caused many secretions/excretions and tissues that had previously been deemed negative to be relabeled as positive for PrP^Sc. This has raised concerns about the possible presence of minimal amounts of PrP^Sc in placentas from ARR foetuses that conventional techniques had indicated were negative. In the present study we examined 30 placentas from a total of 23 gestations; 15 gestations resulted from naturally ARQ/ARQ scrapie-infected ewes mated with ARR/ARR rams. The absence of PrP^Sc in placentas carrying the foetal ARR haplotype (n=19) was determined by IDEXX HerdChek scrapie/BSE Antigen EIA Test, Prionics^®-Check WESTERN and corroborated by the highly sensitive Protein Misfolding Cyclic Amplification technique (PMCA). By immunohistochemistry, several unspecific stainings that might mislead a diagnosis were observed. The results of the present study support that using ARR/ARR males in scrapie eradication programs efficiently decreases the spreading of the agent in the environment via shed placentas.

Factors associated with seminal impairment in HIV-infected men under antiretroviral therapy

STUDY QUESTION

How do semen parameters of HIV-infected men under antiretroviral treatment compare with WHO parameters of normal semen, and what factors are associated with any differences?

SUMMARY ANSWER

Semen quality in most HIV-infected patients under antiretroviral treatment exceeds WHO limits, but the number falling below them is higher than would be expected in a healthy population. Exposure to efavirenz has a significant association with dysmotility.

WHAT IS KNOWN ALREADY

Dysmotility is the most frequently described sperm alteration related to HIV infection, and it has recently been linked to treatment with non-nucleoside reverse transcriptase inhibitors, particularly to efavirenz.

STUDY DESIGN, SIZE, DURATION

Prospective cohort study. Between March 2002 and December 2013, 139 HIV-infected men undergoing antiretroviral therapy were enrolled.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants were male members of serodiscordant couples who attended a clinic for sexually transmitted infections (STIs) in Madrid and requested reproductive counselling. Sociodemographic, behavioural and clinical data were collected. CD4⁺ lymphocyte count, HIV viral load, serology/viral load of hepatitis B and C viruses, syphilis serology and other STIs diagnosis were performed. Semen parameters were assessed through standard sperm analysis and were compared with WHO 2010 reference values. Factors associated with impaired semen parameters were evaluated by bivariate and multivariate analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

The median values of all assessed semen parameters were within a normal range, but in up to 19% of HIV-positive males, at least one parameter of semen quality was below the normal range. A significant association between treatment with efavirenz and the presence of dysmotility was detected in the multivariate analysis.

LIMITATIONS, REASONS FOR CAUTION

Our results cannot demonstrate a causal relationship between exposure to efavirenz and impaired motility. We do not have a real comparison group as the WHO cohort is international and may not reflect local variations in semen characteristics. Subjects who requested reproductive counselling might not be representative of HIV-positive men in general.

WIDER IMPLICATIONS OF THE FINDINGS

Since efavirenz is still widely used in current therapeutic regimens may be affecting fertility in seropositive men who desire procreation.

STUDY FUNDING/COMPETING INTERESTS

No external funding was used for this study. The authors have no conflict of interest to declare.

The architecture of prions: how understanding would provide new therapeutic insights

Compelling evidence from the last three decades clearly shows that transmissible spongiform encephalopathies (TSEs) develop as a result of a poorly understood misfolding event that converts the cellular prion protein (PrPC) to an isoform known as PrPSc which is aggregated, protease resistant and able to impose its aberrant conformation onto PrPC, leading to its accumulation in the central nervous system. Despite all the knowledge gathered in more than thirty years of research and the general understanding of the pathological processes, the molecular mechanisms remain elusive, making it difficult to develop rational therapeutic strategies for this group of incurable diseases. In this review article, we give an overview of what is known about prion architecture and how the limited structural information available has been used in the quest for remedies for these devastating disorders.

Prion-like disorders and Transmissible Spongiform Encephalopathies: An overview of the mechanistic features that are shared by the various disease-related misfolded proteins

Prion diseases or Transmissible Spongiform Encephalopathies (TSEs) are a group of fatal neurodegenerative disorders affecting several mammalian species. Its causative agent, disease-associated prion protein (PrP^d), is a self-propagating β-sheet rich aberrant conformation of the cellular prion protein (PrP^C) with neurotoxic and aggregation-prone properties, capable of inducing misfolding of PrP^C molecules. PrP^d is the major constituent of prions and, most importantly, is the first known example of a protein with infectious attributes. It has been suggested that similar molecular mechanisms could be shared by other proteins implicated in diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis or systemic amyloidoses. Accordingly, several terms have been proposed to collectively group all these disorders. Through the stringent evaluation of those aspects that characterise TSE-causing prions, in particular propagation and spread, strain variability or transmissibility, we will discuss whether terms such as "prion", "prion-like", "prionoid" or "propagon" can be used when referring to the aetiological agents of the above other disorders. Moreover, it will also be discussed whether the term "infectious", which defines a prion essential trait, is currently misused when referring to the other misfolded proteins.

Characterization of mesenchymal stem cells in sheep naturally infected with scrapie

Mesenchymal stem cells (MSCs) can be infected with prions and have been proposed as in vitro cell-based models for prion replication. In addition, autologous MSCs are of interest for cell therapy in neurodegenerative diseases. To the best of our knowledge, the effect of prion diseases on the characteristics of these cells has never been investigated. Here, we analysed the properties of MSCs obtained from bone marrow (BM-MSCs) and peripheral blood (PB-MSCs) of sheep naturally infected with scrapie — a large mammal model for the study of prion diseases. After three passages of expansion, MSCs derived from scrapie animals displayed similar adipogenic, chondrogenic and osteogenic differentiation ability as cells from healthy controls, although a subtle decrease in the proliferation potential was observed. Exceptionally, mesenchymal markers such as CD29 were significantly upregulated at the transcript level compared with controls. Scrapie MSCs were able to transdifferentiate into neuron-like cells, but displayed lower levels of neurogenic markers at basal conditions, which could limit this potential .The expression levels of cellular prion protein (PrPC) were highly variable between cultures, and no significant differences were observed between control and scrapie-derived MSCs. However, during neurogenic differentiation the expression of PrPC was upregulated in MSCs. This characteristic could be useful for developing in vitro models for prion replication. Despite the infectivity reported for MSCs obtained from scrapie-infected mice and Creutzfeldt–Jakob disease patients, protein misfolding cyclic amplification did not detect PrPSc in BM- or PB-MSCs from scrapie-infected sheep, which limits their use for in vivo diagnosis for scrapie.

A cationic tetrapyrrole inhibits toxic activities of the cellular prion protein

Prion diseases are rare neurodegenerative conditions associated with the conformational conversion of the cellular prion protein (PrP^C) into PrP^Sc, a self-replicating isoform (prion) that accumulates in the central nervous system of affected individuals. The structure of PrP^Sc is poorly defined, and likely to be heterogeneous, as suggested by the existence of different prion strains. The latter represents a relevant problem for therapy in prion diseases, as some potent anti-prion compounds have shown strain-specificity. Designing therapeutics that target PrP^C may provide an opportunity to overcome these problems. PrP^C ligands may theoretically inhibit the replication of multiple prion strains, by acting on the common substrate of any prion replication reaction. Here, we characterized the properties of a cationic tetrapyrrole [Fe(III)-TMPyP], which was previously shown to bind PrP^C, and inhibit the replication of a mouse prion strain. We report that the compound is active against multiple prion strains in vitro and in cells. Interestingly, we also find that Fe(III)-TMPyP inhibits several PrP^C-related toxic activities, including the channel-forming ability of a PrP mutant, and the PrP^C-dependent synaptotoxicity of amyloid-β (Aβ) oligomers, which are associated with Alzheimer’s Disease. These results demonstrate that molecules binding to PrP^C may produce a dual effect of blocking prion replication and inhibiting PrP^C-mediated toxicity.

Moderate influenza vaccine effectiveness against hospitalisation with A(H3N2) and A(H1N1) influenza in 2013-14: Results from the InNHOVE network

We conducted a multicentre test negative case control study to estimate the 2013-14 influenza vaccine effectiveness (IVE) against hospitalised laboratory confirmed influenza in 12 hospitals in France, Italy and Spain. We included all ≥18 years hospitalised patients targeted by local influenza vaccination campaign reporting an influenza-like illness within 7 days before admission. We defined as cases patients RT-PCR positive for influenza and as controls those negative for all influenza virus. We used a logistic regression to calculate IVE adjusted for country, month of onset, chronic diseases and age. We included 104 A(H1N1)pdm09, 157 A(H3N2) cases and 585 controls. The adjusted IVE was 42.8% (95%CI: 6.3;65;0) against A(H1N1)pdm09. It was respectively 61.4% (95%CI: -1.9;85.4), 39.4% (95%CI: -32.2;72.2) and 19.7% (95%CI:-148.1;74.0) among patients aged 18-64, 65-79 and ≥80 years. The adjusted IVE against A(H3N2) was 38.1% (95%CI: 8.3;58.2) overall. It was respectively 7.8% (95%CI: -145.3;65.4), 25.6% (95%CI: -36.0;59.2) and 55.2% (95%CI: 15.4;76.3) among patients aged 18-64, 65-79 and ≥80 years. These results suggest a moderate and age varying effectiveness of the 2013-14 influenza vaccine to prevent hospitalised laboratory-confirmed influenza. While vaccination remains the most effective prevention measure, developing more immunogenic influenza vaccines is needed to prevent severe outcomes among target groups.

Aluminium salabza complexes for fixation of CO2 to organic carbonates

A highly stable and easy to synthesize aluminium complex bearing a flexible N₂O₂-donor salabza ligand (N,N′-bis(salicylene)-2-aminobenzylamine) in combination with tetrabutylammonium bromide forms an active binary catalytic system for the cycloaddition of CO₂ to epoxides (TOFs 120–3434 h⁻¹) under mild conditions (10 bar, 80 °C) and low catalyst loadings (0.05–0.2 mol%).

Transgenic Mouse Bioassay: Evidence That Rabbits Are Susceptible to a Variety of Prion Isolates

Interspecies transmission of prions is a well-established phenomenon, both experimentally and under field conditions. Upon passage through new hosts, prion strains have proven their capacity to change their properties and this is a source of strain diversity which needs to be considered when assessing the potential risks associated with consumption of prion contaminated protein sources. Rabbits were considered for decades to be a prion resistant species until proven otherwise recently. To determine the extent of rabbit susceptibility to prions and to assess the effects of passage of different prion strains through this species a transgenic mouse model overexpressing rabbit PrPC was developed (TgRab). Intracerebral challenges with prion strains originating from a variety of species including field isolates (ovine SSBP/1 scrapie, Nor98- scrapie; cattle BSE, BSE-L and cervid CWD), experimental murine strains (ME7 and RML) and experimentally obtained ruminant (sheepBSE) and rabbit (de novo NZW) strains were performed. On first passage TgRab were susceptible to the majority of prions (Cattle BSE, SheepBSE, BSE-L, de novo NZW, ME7 and RML) tested with the exception of SSBP/1 scrapie, CWD and Nor98 scrapie. Furthermore, TgRab were capable of propagating strain-specific features such as differences in incubation periods, histological brain lesions, abnormal prion (PrPd) deposition profiles and proteinase-K (PK) resistant western blotting band patterns. Our results confirm previous studies proving that rabbits are not resistant to prion infection and show for the first time that rabbits are susceptible to PrPd originating in a number of other species. This should be taken into account when choosing protein sources to feed rabbits.

Estimating influenza vaccine effectiveness in Spain using sentinel surveillance data

We aimed to estimate influenza vaccine effectiveness (VE) against laboratory-confirmed influenza during three influenza seasons (2010/11 to 2012/2013) in Spain using surveillance data and to compare the results with data obtained by the cycEVA study, the Spanish component of the Influenza Monitoring Vaccine Effectiveness (I-MOVE) network. We used the test-negative case–control design, with data from the Spanish Influenza Sentinel Surveillance System (SISS) or from the cycEVA study. Cases were laboratory-confirmed influenza patients with the predominant influenza virus of each season, and controls were those testing negative for any influenza virus. We calculated the overall and age-specific adjusted VE. Although the number of patients recorded in the SISS was three times higher than that in the cycEVA study, the quality of information for important variables, i.e. vaccination status and laboratory results, was high in both studies. Overall, the SISS and cycEVA influenza VE estimates were largely similar during the study period. For elderly patients (> 59 years), the SISS estimates were slightly lower than those of cycEVA, and estimates for children (0–14 years) were higher using SISS in two of the three seasons studied. Enhancing the SISS by collecting the date of influenza vaccination and reducing the percentage of patients with incomplete information would optimise the system to provide reliable annual influenza VE estimates to guide influenza vaccination policies.