All procedures involving mouse brains and spleens were performed as described Brain cells begin to die off in massive numbers, eventually leading to the microscopic appearance of "holes" in the brain, degeneration of physical and mental abilities, and ultimately death.
La BSE crée le système de transactions le plus rapide au monde
We studied the behavior and stability of the atypical BSE-H during propagation into a bovine PrP background, thus in the absence of a species barrier. The longer survival times for some mice infected with BSE-H isolates could reflect a lower infectivity of this isolate consistent with the reduction of survival time observed on subpassages, approaching that for BSE-C or BSE-H isolates of presumably higher titer i. Although all BSE-H—inoculated mice showed homogeneous survival times, a phenotypic divergence was observed in a few animals infected with 2 of the BSE-H isolates.
Surprisingly, these few mice showed phenotypic features clearly distinct from those in most of the BSE-H—infected mice but similar to those of BSE-C propagated onto the same mice, according to various criteria. First, a PrP res profile indistinguishable from that produced by BSE-C agent in these mice but clearly distinct from that of BSE-H in cattle, in terms of 1 apparent molecular mass of PrP res , 2 PrP res glycosylation pattern, 3 immunoreactivity with 12B2 mAb, and 4 pattern of labeling with Saf84 antibody.
Second, the vacuolation profile essentially overlapped that in mice infected with BSE-C, with slight differences only in the mesencephalic tegmentum area. These similarities with BSE-C were fully retained after a second passage by using brain homogenate from mice with C-like features, whereas a BSE-H strain phenotype was maintained in mice inoculated with mouse brains homogenates containing H-type PrP res. However, C-like features emerged in only 2 of the 5 isolates tested.
However, a divergent evolution of the BSE agent has been reported after trans-species transmission in both wild-type 11 and human PrP transgenic mice 12 , 39 , Although further studies are required to clarify the mechanisms associated with the emergence of distinct phenotypes among individual mice, several factors would be expected to influence the probability of detecting such a variant through mouse bioassay.
These factors are 1 amount or regions of cattle brain tissue taken for inoculum preparation, 2 physicochemical treatment during inoculum preparation e. Because samples used in this study were prepared from the same region brainstem following the same precise protocol and under identical conditions, differences in inoculum preparation and conditions are unlikely.
However, the possibility that the observations might be influenced by the precise neuroanatomic origin of the inoculated bovine brainstem homogenate or by other mouse bioassay—related factors cannot be excluded. The possible cross-contamination of the BSE-H isolates material and 45 from 2 laboratories in different countries by a BSE-C infectious source was judged highly improbable for several reasons.
These reasons are 1 the strict biosafety procedures followed for sample collection, preparation of the inocula, inoculation scheme, and care of mice; 2 the absence of C-type PrP Sc in the BSE-H inocula used for transmissions as deduced by Western blot analysis; and 3 2 independent transmission experiments, involving separate batches of both incriminated isolates, all produced consistent results.
Together, these observations support 2 possible hypotheses. First, a minor strain component might be present in BSE-H isolates that could emerge on subsequent transmission in Tg mice. In both instances, emergence of the new strain, either in the original cattle or during propagation in Tg mice, could be promoted by specific propagation conditions or by physicochemical treatment of the inoculum.
In this regard, acquisition of novel properties by a sporadic cattle transmissible spongiform encephalopathy agent by a physicochemical treatment, such as that applied to carcass-derived products, has been invoked as a possible origin for the BSE epidemic 7. This agent, however, acquired phenotypic traits intriguingly similar to those of the BSE agent during trans-species transmission in either transgenic mice expressing ovine PrP 28 or inbred mouse lines.
On the basis of these observations, the BSE-C agent already has been speculated to have originated from atypical BSE-L after conversion in an intermediate host such as a sheep.
However, the capacity of these BSE-L—derived agents to retain BSE phenotypic traits after reinoculation to bovine PrP transgenic mice is a key question, remaining to be demonstrated, to show whether the observed convergence truly reflects a permanent strain shift of the BSE-L agent rather than a phenotypic convergence in an experimental model.
In contrast, our results suggest that prion strain divergence might occur on propagation of atypical BSE-H in a homologous bovine PrP context and that this strain divergence could result from a permanent strain shift of the BSE-H agent toward a C-like agent that is stable in subsequent passages.
These findings emphasize the potential capacity of prion diversification during propagation, even in the absence of any species barrier, and represent an experimental demonstration of the capability of an atypical, presumably sporadic, bovine prion to acquire C-like properties during propagation in a homologous bovine PrP context.
Results in transgenic mouse models cannot be directly extrapolated to the natural host. However, our observations are consistent with the view that the BSE agent could have originated from a cattle prion, such as BSE-H, and provide new insights into the nature of the events that could have led to the appearance of this agent.
His research interests include prion strain characterization and evolution and the pathogenesis of prion diseases and their effects on human and animal health. Suggested citation for this article: Classical bovine spongiform encephalopathy by transmission of H-type prion in homologous prion protein context. Emerg Infect Dis [serial on the Internet]. National Center for Biotechnology Information , U. Journal List Emerg Infect Dis v. This article has been cited by other articles in PMC.
Histopathologic Analysis All procedures involving mouse brains and spleens were performed as described Open in a separate window. Discussion We studied the behavior and stability of the atypical BSE-H during propagation into a bovine PrP background, thus in the absence of a species barrier. Footnotes Suggested citation for this article: Bruce ME Scrapie strain variation and mutation. Evidence for the conformation of the pathologic isoform of the prion protein enciphering and propagating prion diversity.
Aguzzi A, Glatzel M Prion infections, blood and transfusions. Nat Clin Pract Neurol. BSE transmission to macaques. Compelling transgenetic evidence for transmission of bovine spongiform encephalopathy prions to humans. Transmission of atypical bovine prions to mice transgenic for human prion protein. Curr Top Microbiol Immunol. Molecular discrimination of atypical bovine spongiform encephalopathy strains from a geographical region spanning a wide area in Europe.
Atypical proteinase K—resistant prion protein PrPres observed in an apparently healthy month-old Holstein steer. Jpn J Infect Dis. Biological and biochemical characterization of L-type-like bovine spongiform encephalopathy BSE detected in Japanese black beef cattle.
Identification and characterization of two bovine spongiform encephalopathy cases diagnosed in the United States. J Vet Diagn Invest. Molecular, biochemical and genetic characteristics of BSE in Canada. Atypical scrapie cases in Germany and France are identified by discrepant reaction patterns in BSE rapid tests. Identification of a second bovine amyloidotic spongiform encephalopathy: Atypical BSE in Germany—proof of transmissibility and biochemical characterization.
Isolation from cattle of a prion strain distinct from that causing bovine spongiform encephalopathy. A bovine prion acquires an epidemic bovine spongiform encephalopathy strain-like phenotype on interspecies transmission. Screening of anti-PrP monoclonal antibodies for their capacity to inhibit PrP Sc replication in infected cells. M [ PubMed ] [ Cross Ref ]. Detection of type 1 prion protein in variant Creutzfeldt-Jakob disease. PrP Sc accumulation in placentas of ewes exposed to natural scrapie: Fraser H, Dickinson AG The sequential development of the brain lesion of scrapie in three strains of mice.
PrP Sc accumulation in myocytes from sheep incubating natural scrapie. Sheep-passaged bovine spongiform encephalopathy agent exhibits altered pathobiological properties in bovine-PrP transgenic mice. Different behavior toward bovine spongiform encephalopathy infection of bovine prion protein transgenic mice with one extra repeat octapeptide insert mutation.
Predicting susceptibility and incubation time of human-to-human transmission of vCJD. La nouvelle plateforme de transactions offre une meilleure efficacité opérationnelle, ainsi qu'un déploiement et une maintenance simplifiés, ce qui permet ainsi à la BSE de répondre aux besoins des traders modernes.
La transition vers le nouveau système s'est faite en toute transparence, sans temps d'arrêt, grâce aux services d'assistance Red Hat. Depuis l'adoption de la solution Red Hat, le volume des transactions traitées par la BSE est passé de 10 millions à millions d'ordres par jour. La vitesse de transaction a été multipliée par plus de 1 , faisant de la plateforme de transactions de la BSE la plus rapide au monde.
Les traders peuvent aussi profiter de services innovants, comme les échanges de devises. Le nombre d'opérations manuelles a également beaucoup diminué. Des tâches qui pouvaient prendre jusqu'à 4 heures sont aujourd'hui effectuées en moins d'une heure. Grâce à cela, la BSE a pu réduire ses besoins en personnel informatique. Quand je pense à Red Hat, la première chose qui me vient à l'esprit, c'est la confiance Chaque fois que nous avons eu besoin d'aide, nous en avons obtenu.
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