Polymorphisms of the prion gene promoter region that influence classical bovine spongiform encephalopathy susceptibility are not applicable to other transmissible spongiform encephalopathies in cattle.

Two regulatory region polymorphisms in the prion gene of cattle have been reported to have an association with resistance to classical bovine spongiform encephalopathy (BSE). However, it is not known if this association also applies to other transmissible spongiform encephalopathies (TSE) in cattle. In this report, we compare the relationship between these 2 polymorphisms and resistance in cattle affected with naturally occurring atypical BSE as well as in cattle experimentally inoculated with either scrapie, chronic wasting disease, or transmissible mink encephalopathy. Our analysis revealed no association between genotype and resistance to atypical BSE or experimentally inoculated TSE. This indicates the promoter polymorphism correlation is specific to classical BSE and that atypical BSE and experimentally inoculated TSE are bypassing the site of influence of the polymorphisms. This genetic discrepancy demonstrates that atypical BSE progresses differently in the host relative to classical BSE. These results are consistent with the notion that atypical BSE originates spontaneously in cattle.

Atypical transmissible spongiform encephalopathies (TSEs) in ruminants.

Transmissible spongiform encephalopathies (TSEs) are associated with the accumulation in infected tissues of a disease-associated form of a host-encoded protein, the prion protein (PrP). Contrary to the normal form of the protein, this form of PrP is partially resistant to protease digestion (PrP(res)). Detailed characterisation of PrP(res) has been intensively investigated in recent years to try and decipher the diversity of TSEs in human and animals. This considerably and unexpectedly enlarged our knowledge about such diseases in ruminants. Previously, such a diversity was essentially shown by the demonstration that scrapie from sheep and goats could have different biological behaviours following transmission of the disease in mice, unlike bovine spongiform encephalopathy from cattle (BSE) which showed a distinct and unique behaviour. The properties of the BSE agent were also demonstrated to be very stable, following transmission to a variety of different species. Molecular studies of PrP(res), followed by transmission studies to mice, gave the first evidence for the accidental transmission of the BSE agent to humans where it induced a variant form of the fatal Creutzfeldt-Jakob disease (CJD) and also to different animal species including a goat in France. This last case was found among a few unusual cases of TSEs in small ruminants that showed some molecular similarities with BSE and which are currently under investigation by transmission studies in mice. The application of the molecular methods to characterise PrP(res) has most recently led to the unexpected discovery of deviant BSE forms in a few affected cattle in Europe and in the United States, which raises the question of a possible different origin at least of some cases of BSE in cattle. Finally, considerable numbers of a new TSE form in small ruminants, referred to as "atypical scrapie" or "Nor98", have meanwhile been identified in most European countries by TSE rapid testing using an assay which recognizes also comparatively less PK resistant PrP(res).

Atypical BSE in Germany--proof of transmissibility and biochemical characterization.

Intensive active surveillance has uncovered two atypical German BSE cases in older cattle which resemble the two different atypical BSE phenotypes that have recently been described in France (designated H-type) and Italy (designated L-type or BASE). The H-type is characterized by a significantly higher molecular size, but a conventional glycopattern of the proteinase K treated abnormal prion protein (PrP(Sc)), while the L-type PrP(Sc) has only a slightly lower molecular size and a distinctly different glycopattern. In this paper we describe the successful transmission of both German atypical BSE cases to transgenic mice overexpressing bovine PrP(C). Upon challenge with the L-type, these mice developed BSE after a substantially shorter incubation period than any classical BSE transmission using these mice to date. In contrast, the incubation period was distinctly prolonged when these mice were challenged with the H-type. PrP(Sc) accumulated in the brains of these mice were of the same atypical BSE type that had been used for the transmission. These atypical cases suggest the possible existence of sporadic BSE cases in bovines. It is thus feasible that the BSE epidemic in the UK could have also been initiated by an intraspecies transmission from a sporadic BSE case.

Estimates of the prevalence of transmissible spongiform encephalopathies in sheep and goats in France in 2002.

An active surveillance programme for transmissible spongiform encephalopathies (TSES) in sheep and goats was implemented in France in 2002 at abattoirs and rendering plants. The analysis of the results of this programme highlighted three biases: a potentially non-random sampling scheme in both rendering plants and abattoirs, a heterogeneous geographical sampling ratio, and the use of two diagnostic tests of unequal sensitivity. Simulations were run to estimate the prevalence of TSES by taking these biases into account. A comparison of the prevalence of TSES calculated from the raw data with the simulation results showed that the effects of non-random sampling were minor in comparison with the effects of the heterogeneous geographical sampling ratio and the use of two diagnostic tests.

Atypical scrapie cases in Germany and France are identified by discrepant reaction patterns in BSE rapid tests.

The intensified surveillance of scrapie in small ruminants in the European Union (EU) has resulted in a substantial increase of the number of diagnosed cases. Four rapid tests which have passed the EU evaluation for BSE testing of cattle are also recommended currently and used for the testing of small ruminants by the EU authorities. These tests include an indirect ELISA (cELISA), a colorimetric sandwich ELISA (sELISA I), a chemiluminescent sandwich ELISA (sELISA II), and a Western blot (WB). To this point, the majority of samples have been screened by using either sELISA I (predominantly in Germany) or WB (predominantly in France). In this study, it is shown that a number of the German and French scrapie cases show inconsistent results using rapid and confirmatory test methods. Forty-eight German sheep, 209 French sheep and 19 French goat transmissible spongiform encephalopathy (TSE) cases were tested. All cases were recognised by the sELISA I and either one of the confirmatory methods (scrapie-associated fibrils (SAF)-immunoblot or immunohistochemistry). Surprisingly, three rapid tests failed to detect a significant number of scrapie cases (29 in France and 24 in Germany). The possible reasons for these inconsistent reaction patterns of scrapie cases are discussed. Similar discrepancies have not been observed during rapid testing of cattle for BSE, the disease for which all diagnostic methods applied have been evaluated.

Targeted surveillance to assess the prevalence of BSE in high-risk populations in western France and the associated risk factors.

A pilot study was set up for the first time in France in August 2000, to obtain more precise estimates on the BSE epidemic in France. Three categories of cattle at risk of BSE (found dead on-farm, euthanased and emergency slaughtered) were sampled exhaustively from August 7 to December 22, 2000, in the three regions assumed to be the most affected with BSE in France (Basse-Normandie, Bretagne and Pays de la Loire). The samples were checked by using Prionics tests, and positive samples were confirmed by Western blot or immunohistochemistry. The overall prevalence of positive cattle was 0.16 per cent. Multifactorial logistic regression showed that there was a significantly higher prevalence among cattle from the birth cohorts July 1993 to June 1994 and July 1994 to June 1995, than among those born before July 1993, and among the categories 'euthanased' and 'emergency slaughtered' than among the category 'dead on-farm, and a higher prevalence in the regions Pays de la Loire and Bretagne than in Basse-Normandie. No significant differences in the prevalence of BSE were observed between dairy, beef suckler and mixed herds.

[Hashimoto's encephalopathy: an anatomicoclinical observation]. / Encéphalopathie d'Hashimoto: une observation anatomo-clinique.

Hashimoto's encephalopathy (HE) is a rare neurological complication of chronic lymphocytic thyroiditis. As its clinical presentation is aspecific, other etiologies of acute encephalopathy have to be ruled out. We report the case of a 29-year old woman with neuropsychiatric signs preceding coma, myoclonus and epileptic seizures. Clinical and electroencephalographic features were consistent with the diagnosis of new variant of Creutzfeldt-Jakob disease. However, high titres of antithyroid antibodies in serum directed towards the diagnosis of HE. Despite oral steroids, the patient died five months later. Neuropathological findings ruled out spongiform encephalopathy and disclosed aspecific activated microglia. Our observation suggests that this process could be involved in the pathogenesis of HE. Even in the absence of clinical dysthyroidism, HE diagnosis has to be suspected in the settings of acute encephalopathy associated with seric antithyroid antibodies.

Molecular analysis of the abnormal prion protein during coinfection of mice by bovine spongiform encephalopathy and a scrapie agent.

Molecular features of the proteinase K-resistant prion protein (PrP res) may discriminate among prion strains, and a specific signature could be found during infection by the infectious agent causing bovine spongiform encephalopathy (BSE). To investigate the molecular basis of BSE adaptation and selection, we established a model of coinfection of mice by both BSE and a sheep scrapie strain (C506M3). We now show that the PrP res features in these mice, characterized by glycoform ratios and electrophoretic mobilities, may be undistinguishable from those found in mice infected with scrapie only, including when mice were inoculated by both strains at the same time and by the same intracerebral inoculation route. Western blot analysis using different antibodies against sequences near the putative N-terminal end of PrP res also demonstrated differences in the main proteinase K cleavage sites between mice showing either the BSE or scrapie PrP res profile. These results, which may be linked to higher levels of PrP res associated with infection by scrapie, were similar following a challenge by a higher dose of the BSE agent during coinfection by both strains intracerebrally. Whereas PrP res extraction methods used allowed us to distinguish type 1 and type 2 PrP res, differing, like BSE and scrapie, by their electrophoretic mobilities, in the same brain region of some patients with Creutzfeldt-Jakob disease, analysis of in vitro mixtures of BSE and scrapie brain homogenates did not allow us to distinguish BSE and scrapie PrP res. These results suggest that the BSE agent, the origin of which remains unknown so far but which may have arisen from a sheep scrapie agent, may be hidden by a scrapie strain during attempts to identify it by molecular studies and following transmission of the disease in mice.

[Non-familial Creutzfeldt-Jakob disease: a study of 53 cases]. / Maladie de Creutzfeldt-Jakob non familiale certaine: étude de 53 observations.

Creutzfeldt-Jakob disease (CJD) is the most frequent human spongiform encephalopathy. We have analyzed 53 cases of definite non familial CJD over a study period of 28 years. All were autopsied in the same neuropathological unit. Clinical and epidemiological data were in accordance with previous studies: low incidence of CJD under the age of 40, high incidence around the sixty years of age (26%) a sex ratio at 0.65 and high frequency of myoclonus, dementia and cerebellar ataxia during evolution (78%). This study highlights the rapidity at the onset of the disease (within 24 hours) in 16% of the cases. EEG disclosed typical pseudoperiodic activity in only 53% of cases and cerebral MRI showed high T2 signal intensity in basal nuclei in 15%. This regional study is the second of its nature to be carried out in France, the first one covering the area of Paris.

Protection of personnel and environment against Creutzfeldt-Jakob disease in pathology laboratories.

Most neuropathology laboratories have been faced with the question of dealing with cases of Creutzfeldt-Jakob disease (CJD) which is a rare neurodegenerative disorder. Neuropathologists have been long aware of the transmissibility and unique properties of the agent which make it resistant to conventional inactivating reagents. The emergence of iatrogenic cases and of the bovine spongiform encephalopathy (BSE) crisis has induced anxiety among laboratory staff and raised questions about the efficiency of safety measures and procedures hitherto applied in pathology laboratories. This article aims at presenting an overview of the risk involved in handling CJD material. It gives practical advice and a key to more detailed procedures, guidelines and recommendations available in scientific literature and through government agencies. Neuropathologists and biochemists are at a higher potential risk than others since the diagnosing of CJD involves the handling of nervous tissue which contains the highest levels of infectivity.