Perméabilité des barrières de transmission et évaluation du risque iatrogène associé aux agents responsables des Encéphalopathies Spongiformes Transmissibles

Les Encéphalopathies Spongiformes transmissibles (EST) sont des maladies neurodégénératives fatales caractérisées par l’accumulation d’un conformère anormal (PrPSc) d’une protéine de l’hôte (PrP). Chez l’homme, plusieurs centaines de cas de transmissions iatrogènes de la maladie de Creutzfeldt Jakob (MCJ) ont été identifiées, notamment chez des patients ayant fait l’objetd’ une greffe de dure-mère, de cornée ou des injections d’hormones de croissance extractives. Plus récemment, plusieurs cas du variant de la maladie de Creutzfeldt Jakob (vMCJ) ont été observés chez des patients transfusés avec des produits sanguins issus de donneurs en incubation de la maladie. D’un point de vue sanitaire, l’évaluation du risque de contamination interindividuelle par des tissus ou des fluides biologiques issus de patients atteints représente un enjeu important en matière de santé publique. La première partie de notre travail a consisté à comparer la sensibilité relative de modèles de souris transgéniques sur-exprimant la PrP à celle de l’hôte conventionnel exprimant la même séquence. Les résultats obtenus ont validé le concept d’une absence d’impact du niveau d’expression de la PrP ou du fond génétique de l’hôte sur la sensibilité finale du modèle à l’infection. A l’aide de ces modèles de souris transgéniques, nous avons alors mesuré les niveaux d’infectiosité dans le sang de patients atteints de différentes formes d’’EST. Chez un patient atteint de vMCJ, nous avons mis en évidence de faibles niveaux d’infectiosité dans les concentrés de globules rouges, les leucocytes et le plasma. Nous avons également pu détecter de l’infectiosité dans le plasma issu de 2 patients atteints de sMCJ sur 4 testés. Parallèlement à ces expériences, nous avons démontré dans un modèle expérimental d’infection chez le mouton, que l’administration de 104 à 105 leucocytes suffisent à transmettre par voire transfusionnelle la maladie. Ces résultats soulignent l’intérêt et les limites de la leuco-déplétion appliquée de manière standard en médicine transfusionnelle, pour limiter les risques de transmission du vMCJ. Enfin, nous avons testé la capacité de différents outils in vitro à détecter la présence des Prions dans le sang. ABSTRACT : Transmissible spongiform encephalopathies (TSE) are fatal neurodegenerative disorders occurring in a wide spectrum of animals. They are characterized by accumulation of abnormally folded conformers (PrPSc) derived from normal cellular PrP protein (PrP) of the host. In human, many iatrogenic transmissions of Creutzfeldt Jakob disease (CJD) have been reported after dura mater graft, corneal graft or extractive growth hormone injections, prepared from affected donors. More recently, several cases of vCJD transmissions were reported in individuals that were transfused with blood from asymptomatic donors that subsequently developed vCJD. Risk assessment of interindividual transmission with contaminated tissues or body fluids remains a major public health issue. In a first part, we validated the final pertinence of infectious titers as measured in mice overexpressing PrP to the risk of transmitting the disease in the natural host species. In a second time, we used this model to evaluate the presence of infectivity in blood from TSE affected patients. We were able to detect the presence of infectivity in erythrocytes, leukocytes, and plasma of 1 person with vCJD and in the plasma of 2 out of 4 persons whose tests were positive for sporadic CJD. We then demonstrated in a sheep TSE model, that intravenous administration of 104 to 105 leucocytes was sufficient to cause disease in recipient sheep, underlying the efficacy and potential limits of leuko-reduction processes that are currently applied in transfusion medicine to mitigate the TSE transmission risk. Finally, using the same model, we tested different in vitro methods to detect prions in blood

Infections à Riemerella anatipestifer chez le canard mulard : analyse des facteurs de risque et des mesures de contrôle

Les infections à Riemerella anatipestifer sont actuellement une dominante pathologique majeure chez le canard mulard. Cette entité est un syndrome multifactoriel complexe incluant des facteurs de risques techniques voire viraux. L'objectif de ce travail est de réaliser une synthèse des données épidémiologiques disponibles sur la base d'une enquête rétrospective, pour évaluer la dynamique de l'infection, l'évolution des nombreux sérotypes isolés et la relation entre les sérotypes isolés sur des sujets porteurs sains et ceux isolés de cas cliniques. Cette enquête est basée sur l'ensemble des cas apparus au cours de l'hiver 2006 dans le Sud-ouest de la France. Elle a permis de dégager un profil technique et sanitaire des lots touchés mais n'explique pas à elle seule la résurgence actuelle de cas. Ces critères devront être analysés au travers d'une étude longitudinale sur des sites d'élevage présentant un profil à risque, donnant lieu à l'étude du rôle immunodépresseur éventuel d'infections virales pouvant expliquer des cas récurrents ou des échecs de vaccination

Differential astrocyte and oligodendrocyte vulnerability in murine Creutzfeldt-Jakob disease

Glial vulnerability to prions is assessed in murine Creutzfeldt-Jakob disease (CJD) using the tg340 mouse line expressing four-fold human PrP M129 levels on a mouse PrP null background at different days following intracerebral inoculation of sCJD MM1 brain tissues homogenates. The mRNA expression of several astrocyte markers, including glial fibrillary acidic protein (gfap), aquaporin-4 (aqp4), solute carrier family 16, member 4 (mct4), mitochondrial pyruvate carrier 1 (mpc1) and solute carrier family 1, member 2 (glial high-affinity glutamate transporter, slc1a2) increases at 120 and 180 dpi. In contrast, the mRNA expression of oligodendrocyte and myelin markers oligodendrocyte transcription factor 1 (olig1), olig2, neural/glial antigen 2 (cspg), solute carrier family 16, member 1 (mct1), myelin basic protein (mbp), myelin oligodendrocyte glycoprotein (mog) and proteolipid protein 1 (plp1) is preserved. Yet, myelin regulatory factor (myrf) mRNA is increased at 180 dpi. In the striatum, a non-significant increase in the number of GFAP-positive astrocytes and Iba1-immunoreactive microglia occurs at 160 dpi; a significant increase in the number of astrocytes and microglia, and a significant reduction in the number of Olig2-immunoreactive oligodendrocytes occur at 180 dpi. A decrease of MBP, but not PLP1, immunoreactivity is also observed in the striatal fascicles. These observations confirm the vulnerability and the reactive responses of astrocytes, together with the microgliosis at middle stages of prion diseases. More importantly, these findings show oligodendrocyte vulnerability and myelin alterations at advanced stages of murine CJD. They confirm oligodendrocyte involvement in the pathogenesis of CJD

Distribution and quantitative estimates of variant Creutzfeldt Jakob Diseases prions in the tissues of clinical and asymptomatic patients

In the United-Kingdom, ≈1 of 2,000 persons could be infected with variant Creutzfeldt-Jakob disease (vCJD). Therefore, risk of transmission of vCJD by medical procedures remains a major concern for public health authorities. In this study, we used in vitro amplification of prions by protein misfolding cyclic amplification (PMCA) to estimate distribution and level of the vCJD agent in 21 tissues from 4 patients who died of clinical vCJD and from 1 asymptomatic person with vCJD. PMCA identified major levels of vCJD prions in a range of tissues, including liver, salivary gland, kidney, lung, and bone marrow. Bioassays confirmed that the quantitative estimate of levels of vCJD prion accumulation provided by PMCA are indicative of vCJD infectivity levels in tissues. Findings provide critical data for the design of measures to minimize risk for iatrogenic transmission of vCJD

The emergence of classical BSE from atypical/Nor98 scrapie

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.info:eu-repo/semantics/acceptedVersio

The emergence of classical BSE from atypical/Nor98 scrapie.

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.This work was funded by FEDER POCTEFA TRANSPRION (EFA282/13) and REDPRION (EFA148/16), by the UK Food Standards Agency Exploring permeability of the species barrier (M03043 and FS231051), by the European Union through FP7 222887 “Priority”, the Spanish Ministerio de Economía y Competitividad [AGL2016-78054-R (AEI/FEDER, UE). A.M.-M. was supported by a fellowship from the INIA (FPI-SGIT-2015-02), and P.A.-C. was supported by a fellowship from the Spanish Ministerio de Economía y Competitividad (BES-2010-040922)

Submicroscopic Deletions at 13q32.1 Cause Congenital Microcoria.

International audienceCongenital microcoria (MCOR) is a rare autosomal-dominant disorder characterized by inability of the iris to dilate owing to absence of dilator pupillae muscle. So far, a dozen MCOR-affected families have been reported worldwide. By using whole-genome oligonucleotide array CGH, we have identified deletions at 13q32.1 segregating with MCOR in six families originating from France, Japan, and Mexico. Breakpoint sequence analyses showed nonrecurrent deletions in 5/6 families. The deletions varied from 35 kbp to 80 kbp in size, but invariably encompassed or interrupted only two genes: TGDS encoding the TDP-glucose 4,6-dehydratase and GPR180 encoding the G protein-coupled receptor 180, also known as intimal thickness-related receptor (ITR). Unlike TGDS which has no known function in muscle cells, GPR180 is involved in the regulation of smooth muscle cell growth. The identification of a null GPR180 mutation segregating over two generations with iridocorneal angle dysgenesis, which can be regarded as a MCOR endophenotype, is consistent with the view that deletions of this gene, with or without the loss of elements regulating the expression of neighboring genes, are the cause of MCOR

Allelic Interference in Prion Replication Is Modulated by the Convertibility of the Interfering PrPC and Other Host-Specific Factors

17 Pág.Early studies in transgenic mouse lines have shown that the coexpression of endogenous murine prion protein (PrPC) and transgenic PrPC from another species either inhibits or allows the propagation of prions, depending on the infecting prion strain and interacting protein species. The way whereby this phenomenon, so-called "interference," is modulated remains to be determined. In this study, different transgenic mouse lines were crossbred to produce mice coexpressing bovine and porcine PrPC, bovine and murine PrPC, or murine and porcine PrPC These animals and their respective hemizygous controls were inoculated with several prion strains from different sources (cattle, mice, and pigs) to examine the effects of the simultaneous presence of PrPC from two different species. Our results indicate interference with the infection process, manifested as extended survival times and reduced attack rates. The interference with the infectious process was reduced or absent when the potentiality interfering PrPC species was efficiently converted by the inoculated agent. However, the propagation of the endogenous murine PrPSc was favored, allowing us to speculate that host-specific factors may disturb the interference caused by the coexpression of an exogenous second PrPC IMPORTANCE Prion propagation can be interfered with by the expression of a second prion protein in the host. In the present study, we investigated prion propagation in a host expressing two different prion protein genes. Our findings indicate that the ability of the second prion protein to interfere with prion propagation is related to the transmissibility of the prion in the host expressing only the interfering prion protein. The interference detected occurs in a prion strain-dependent manner. Interestingly, a bias favoring the propagation of the murine PrP allele has been observed. These results open the door to future studies in order to determine the role of host factors other than the PrP amino acid sequence in the interference in prion propagation.This work was funded by EU Projects FOOD-CT-2006-36353 (Goat-BSE) and CT2009-222887 (Priority) and by the Spanish Ministerio de Economía y Competitividad (grant AGL2016-78054-R [AEI/FEDER, UE]) and a fellowship (BES-2010-040922) to P.A.-C. A.M.-M. was supported by a fellowship from the INIA (FPI-SGIT-2015-02).Peer reviewe