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1.
To detect prion protein, brains from 5 cattle naturally affected with bovine spongiform encephalopathy (BSE) and 3 sheep naturally affected with scrapie were examined and compared with brains of normal cattle and sheep using a histoblot technique. The technique enabled the in situ distinctive detection of the cellular (PrP(C)) and abnormal (PrP(Sc)) isoforms of the prion protein. In BSE- or scrapie-affected brains, the Prp(C) signal decreased, especially in those areas where the PrP(Sc) signal was detected.  相似文献   

2.
The effect of autolysis on the electron microscopic detection of the characteristic abnormal fibrils, originally called 'scrapie-associated fibrils', was investigated in four different areas of the central nervous system (CNS) from 10 clinically suspect BSE cattle after post mortem delay and compared with the histopathological diagnosis. The tissues for fibril detection were subjected to controlled incubations to simulate autolysis. Fibril detection in all areas sampled from nine animals in which BSE was confirmed by histopathology was not affected by combined post mortem delays and specific controlled treatments. Detection of fibrils from the cervical spinal cord was no less sensitive than from brain areas. Fibrils were not detected in the one suspect case in which histopathology did not reveal lesions of BSE. The study confirms that fibril detection is of diagnostic value in BSE when post mortem autolysis renders CNS material unsuitable for histopathology.  相似文献   

3.
Seventeen clinically suspect scrapie sheep, and twelve suspected BSE-affected cattle were confirmed using routine histopathological examination by the detection of characteristic spongiform change in the medulla brain region taken at the level of the obex. Three sheep and four cows acquired as controls showed no spongiform change. Five aliquots of brain tissue from each of four brain regions were taken (cerebellum, medulla, frontal cerebral cortex and occipital cerebral cortex) from each of the 36 animals. One aliquot was frozen at -70 degrees C, the others were subjected to one of four autolysis regimes at 3 or 7 days at 25 degrees C or 37 degrees C. All samples were tested by Western immunoblotting for detection of PrP(Sc) using the Prionics - Check test (Prionics AG, Zurich, Switzerland). Further samples of medulla from 15 suspect scrapie cases, 10 healthy sheep, 13 suspect BSE cows and 5 healthy cows, were taken adjacent to the obex, and subjected to autolysis at 37 degrees C for 6, 12, 24 and 48 hours before being fixed in 10 per cent formal saline and subsequently examined by a routine immunohistochemical technique for detection of PrP(Sc) protein. The abnormal protein could not be detected in any of the control animals by either technique. PrP(Sc) could be detected by Western immunoblotting in at least one brain area from all the positive animals after autolysis for 7 days at 37 degrees C. The protein could be detected by immunohistochemistry in all cases which were positive by histopathological examination using all autolysis conditions. From the results of this study it is concluded that autolysis does not significantly compromise the diagnosis of scrapie or BSE by either of these diagnostic methods.  相似文献   

4.
The origin and transmission routes of atypical bovine spongiform encephalopathy (BSE) remain unclear. To assess whether the biological and biochemical characteristics of atypical L-type BSE detected in Japanese cattle (BSE/JP24) are conserved during serial passages within a single host, 3 calves were inoculated intracerebrally with a brain homogenate prepared from first-passaged BSE/JP24-affected cattle. Detailed immunohistochemical and neuropathologic analysis of the brains of second-passaged animals, which had developed the disease and survived for an average of 16 months after inoculation, revealed distribution of spongiform changes and disease-associated prion protein (PrP(Sc)) throughout the brain. Although immunolabeled PrP(Sc) obtained from brain tissue was characterized by the presence of PrP plaques and diffuse synaptic granular accumulations, no stellate-type deposits were detected. Western blot analysis suggested no obvious differences in PrP(Sc) molecular mass or glycoform pattern in the brains of first- and second-passaged cattle. These findings suggest failures to identify differences in mean incubation period and biochemical and neuropathologic properties of the BSE/JP24 prion between the first and second passages in cattle.  相似文献   

5.
In 2005, a prion disease identified in a goat from France was reported to be consistent with disease from the bovine spongiform encephalopathy (BSE) agent. Subsequent retrospective examination of UK goat scrapie cases led to the identification of one potentially similar, but as yet unconfirmed, case from Scotland. These findings strengthened concerns that small ruminant populations exposed to the BSE agent have become infected. The lack of data relating specifically to scrapie in goats has been contributory to past assumptions that, in general, sheep and goats respond similarly to prion infections. In this study, brain material from 22 archived caprine scrapie cases from the UK was reviewed by histopathology and by immunohistochemical examination for accumulations of disease-specific prion protein (PrP(Sc)) to provide additional data on the lesions of caprine scrapie and to identify any BSE-like features. The vacuolar change observed in the goats was characteristic of transmissible spongiform encephalopathies in general. PrP(Sc) immunohistochemical morphologic forms described in scrapie and experimental BSE infections of sheep were demonstrable in the goats, but these were generally more extensive and variable in PrP(Sc) accumulation. None of the cases examined showed a PrP(Sc) immunohistochemical pattern indicative of BSE.  相似文献   

6.
Resistance of cattle to scrapie by the oral route.   总被引：2，自引：0，他引：2  
Early epidemiological information indicated that bovine spongiform encephalopathy (BSE) originated from scrapie in sheep. The question arose if scrapie in North America would induce a BSE-like disease in cattle. Six years ago, we reported that brain tissue from sheep with scrapie caused a neurologic disease when injected directly into the brains of cattle, but the disease induced was different from BSE as it occurs in the United Kingdom and Europe. Here, we report that cattle fed raw brain or meat and bone meal and tallow prepared from sheep with scrapie remained normal for 8 years after exposure. This work indicates that cattle are highly resistant to North American scrapie by the oral route.  相似文献   

7.
An assessment was made of the risks of bovine spongiform encephalopathy (BSE) occurring in Argentina. Most of the factors associated with the origin and development of the BSE epidemic in the UK are essentially absent. For example, Argentina's large sheep and cattle industries are based on low-cost production systems using grass. Concentrated feeds are not used for sheep, rarely for beef cattle and to a comparatively modest extent for dairy cows. Particularly important are the facts that scrapie (and BSE) has never been reported in Argentina—very small amounts of waste tissues from sheep are rendered to produce meat and bone meal (MBM)—and MBM is not used in concentrated feeds for cattle. We conclude that Argentina has an exceptionally low risk of BSE due to scrapie. There is a very small risk of BSE having been introduced via live animals imported from countries with BSE, but this could only give rise to isolated cases because MBM is not fed to cattle.

A surveillance programme has been carried out based largely on a histological examination of brains from three categories of old dairy cows: animals reported on the suspicion of having neurological disease; animals in poor condition at slaughter; healthy animals randomly selected in the abattoir. No evidence of transmissible spongiform encephalopathy was seen in several sections from each of a total of 1019 brains. We conclude that, for most practical purposes, Argentina may be considered to be free from BSE.  相似文献   


8.
A 19-month-old greater kudu (Tragelaphus strepsiceros), whose dam had died 15 months earlier with spongiform encephalopathy, required euthanasia after developing severe ataxia and depression with an apparently sudden onset. No macroscopic abnormalities were detected on post mortem examination but a scrapie-like spongiform encephalomyelopathy was apparent on histopathological examination of brain and segments of spinal cord. Negative stain electron microscopy of proteinase K-treated detergent extracts of tissue from the brain stem revealed the presence of scrapie associated fibrils, and a 25 to 28 kDa band comparable with that identified as abnormal PrP (prion protein) from the brains of domestic cattle with spongiform encephalopathy was detected using rabbit antiserum raised against mouse PrP. The animal was born nine months after the statutory ban on the inclusion of ruminant-derived protein in ruminant feeds and, as no other possible sources of the disease were apparent, it appears likely that the infection was acquired from the dam.  相似文献   

9.
Extracts from the cervical spinal cord and from the medulla, thalamus, cerebellum and cerebral cortex of the brains of 10 sheep, histopathologically confirmed as cases of scrapie, were examined by electron microscopy for the presence of scrapie-associated fibrils. Characteristic fibrils were observed in all the extracts except for that from the thalamus of one sheep. No fibrils were found in any extracts from three control sheep. A comparison of these results with a similar study of 22 cases of bovine spongiform encephalopathy (BSE) suggests that in cases of scrapie the area of the brain chosen for the detection of fibrils is less critical than in cases of BSE, in which fibrils are more readily extracted from areas of the brain stem.  相似文献   

10.
Diagnosis of bovine spongiform encephalopathy: a review   总被引：1，自引：0，他引：1  
Cows affected with bovine spongiform encephalopathy (BSE) display chronic neurological signs consisting of behavioural changes, abnormalities of posture and movement, and/or hyperaesthesia. At present, there are no laboratory test available to diagnose BSE in the live animal. In this article, we describe the post-mortem diagnostic examination of brains from BSE-suspected cattle as currently performed at ID-Lelystad. The routine laboratory diagnosis of BSE consists of histopathological examination of the brain and detection of the modified prion protein, PrP(BSE), in brain tissue. These tests, however, have the disadvantage of being laborious and time consuming, so that results are available only after several days. Recently, at ID-Lelystad a new post-mortem test has been developed that enables screening of larger volumes of brain samples for PrP(BSE) within 1 day. This BSE test is especially suited for slaughterline monitoring. A preliminary validation study has shown that both sensitivity and specificity are 100% compared to the gold diagnostic standard of histopathology.  相似文献   

11.
The transmissible spongiform encephalopathies of domesticated animals, scrapie in-sheep and bovine spongiform encephalopathy (BSE), and transmissible mink encephalopathy are more than a scientific curiosity; under certain circumstances their impact on commercial activities can be calamitous. Knowledge of their causation and pathogenesis is still rudimentary, but many consider than an unconventional agent, the prion (a brain protein, PrP), that is not associated with nucleic acid is involved in both. Others believe that conventional viruses, which replicate by virtue of their nucleic acid-defined genes, are involved in the causation and progression of the encephalopathies but that technical problems have prevented their identification. Others postulate even more exotic causative agents. While this paper will particularly address the possibility of a viral aetiology for these diseases, it is also emphasized that our knowledge of the state of the immune system in animals with encephalopathy needs broadening. There are remarkable gaps in our knowledge of the histopathology of these diseases, particularly the nature of the characteristic vacuoles. Much further work is needed on the biochemical changes in the brain and the serum, particularly of the latter as it could lead to an additional means of recognizing clinical cases without waiting for the animal to die with subsequent examination of the brain for characteristic lesions and the presence of protease-K-resistant PrP.Abbreviations AI artificial insemination - BSE bovine spongiform encephalopathy - CJD Creutzfeldt-Jakob disease - ET embryo transfer - GSSD Gerstmann-Sträussler-Scheinker disease - HDV hepatitis delta virus - MCF mink cell focus - PK proteinase K - PrP prion protein - PrPSc scrapie prion protein - PrP-C the proteinase-K sensitive homologue in normal brain - SAF scrapie-associated fibrils - TME transmissible mink encephalopathy  相似文献   

12.
Bovine spongiform encephalopathy (BSE) is a fatal neurodegenerative disorder of cattle characterized by accumulation of the disease-associated prion protein (PrP(Sc)) in the central nervous system (CNS). The immunohistochemical patterns and distribution of PrP(Sc) were investigated in the CNS, brains, and spinal cords of 7 naturally occurring BSE cases confirmed by the fallen stock surveillance program in Japan. No animals showed characteristic clinical signs of the disease. Coronal slices of 14 different brain areas in each case were immunohistochemically analyzed using an anti-prion protein antibody. Immunolabeled PrP(Sc) deposition was widely observed throughout each brain and spinal cord. Intense PrP(Sc) deposition was greater in the thalamus, brainstem, and spinal cord of the gray matter than in the neocortices. The topographical distribution pattern and severity of PrP(Sc) accumulation were mapped and plotted as immunohistochemical profiles of the different brain areas along the caudal-rostral axis of the brain. The distribution pattern and severity of the immunolabeled PrP(Sc) in the CNS were almost the same among the 7 cases analyzed, suggesting that the naturally occurring cases in this study were at the preclinical stage of the disease. Immunohistochemical mapping of the PrP(Sc) deposits will be used to clarify the different stages of BSE in cattle.  相似文献   

13.
Brain tissue from a case of bovine spongiform encephalopathy (BSE) from Alberta was subjected to a Western immunoblotting technique to ascertain the molecular profile of any disease-specific, abnormal prion protein, that is, prion protein that is protease-resistant (PrP(res)). This technique can discriminate between isolates from BSE, ovine scrapie, and sheep experimentally infected with BSE. Isolates of brain tissue from the BSE case in Alberta, 3 farmed elk with chronic wasting disease (CWD) from different parts of Saskatchewan, and 1 farmed white-tailed deer with CWD from Edmonton, Alberta, were examined alongside isolates of brain tissue from BSE, ovine scrapie, and sheep experimentally infected with BSE from the United Kingdom (UK). The molecular weights of PrP(res) and the cross reactions to 2 specific monoclonal antibodies (mAbs) were determined for each sample. The BSE isolates from Canada and the UK had very similar PrP(res) molecular weights and reacted with only 1 of the 2 mAbs. The PrP(res) isolated from both elk and white-tailed deer with CWD had a higher molecular weight profile than did the corresponding PrP(res) from the scrapie and BSE isolates. The PrP(res) from CWD cases cross reacted with both mAbs, a property shared with PrP(res) in isolates from scrapie but not with PrP(res) isolates from BSE or sheep experimentally infected with BSE. The results from this study seem to confirm that the PrP(res) isolated from the BSE case in Alberta has similar molecular properties to the PrP(res) isolated from a BSE case in the UK, and that it differs in its molecular and immunological characteristics from the CWD and scrapie cases studied.  相似文献   

14.
To compare clinicopathologic findings of transmissible mink encephalopathy (TME) with other transmissible spongiform encephalopathies (TSE, prion diseases) that have been shown to be experimentally transmissible to cattle (sheep scrapie and chronic wasting disease [CWD]), two groups of calves (n = 4 each) were intracerebrally inoculated with TME agents from two different sources (mink with TME and a steer with TME). Two uninoculated calves served as controls. Within 15.3 months postinoculation, all animals from both inoculated groups developed clinical signs of central nervous system (CNS) abnormality; their CNS tissues had microscopic spongiform encephalopathy (SE); and abnormal prion protein (PrP(res)) as detected in their CNS tissues by immunohistochemistry (IHC) and Western blot (WB) techniques. These findings demonstrate that intracerebrally inoculated cattle not only amplify TME PrP(res) but also develop clinical CNS signs and extensive lesions of SE. The latter has not been shown with other TSE agents (scrapie and CWD) similarly inoculated into cattle. The findings also suggest that the diagnostic techniques currently used for confirmation of bovine spongiform encephalopathy (BSE) would detect TME in cattle should it occur naturally. However, it would be a diagnostic challenge to differentiate TME in cattle from BSE by clinical signs, neuropathology, or the presence of PrP(res) by IHC and WB.  相似文献   

15.
Scrapie and bovine spongiform encephalopathy (BSE) are both prion diseases affecting ruminants, and these diseases do not share the same public health concerns. Surveillance of the BSE agent in small ruminants has been a great challenge, and the recent identification of diverse prion diseases in ruminants has led to the development of new methods for strain typing. In our study, using immunohistochemistry (IHC), we assessed the distribution of PrP(d) in the brains of 2 experimentally BSE-infected sheep with the ARQ/ARQ genotype. Distribution of PrP(d) in the brain, from the spinal cord to the frontal cortex, was remarkably similar in the 2 sheep despite different inoculation routes and incubation periods. Comparatively, overall PrP(d) brain distribution, evaluated by IHC, in 19 scrapie cases with the ARQ/ARQ, ARQ/VRQ, and VRQ/VRQ genotypes, in some cases showed similarities to the experimentally BSE-infected sheep. There was no exclusive neuroanatomical site with a characteristic and specific PrP(d) type of accumulation induced by the BSE agent. However, a detailed analysis of the topography, types, and intensity of PrP(d) deposits in the frontal cortex, striatum, piriform cortex, hippocampus, mesencephalon, and cerebellum allowed the BSE-affected sheep group to be distinguished from the 19 scrapie cases analyzed in our study. These results strengthen and emphasize the potential interest of PrP(d) brain mapping to help in identifying prion strains in small ruminants.  相似文献   

16.
Bovine spongiform encephalopathy (BSE) is a transmissible spongiform encephalopathy of cattle, first detected in 1986 in the United Kingdom and subsequently in other countries. It is the most likely cause of variant Creutzfeldt-Jakob disease (vCJD) in humans, but the origin of BSE has not been elucidated so far. This report describes the identification and characterization of two cases of BSE diagnosed in the United States. Case 1 (December 2003) exhibited spongiform changes in the obex area of the brainstem and the presence of the abnormal form of the prion protein, PrP(Sc), in the same brain area, by immunohistochemistry (IHC) and Western blot analysis. Initial suspect diagnosis of BSE for case 2 (November 2004) was made by a rapid ELISA-based BSE test. Case 2 did not exhibit unambiguous spongiform changes in the obex area, but PrP(Sc) was detected by IHC and enrichment Western blot analysis in the obex. Using Western blot analysis, PrP(Sc) from case 1 showed molecular features similar to typical BSE isolates, whereas PrP(Sc) from case 2 revealed an unusual molecular PrP(Sc) pattern: molecular mass of the unglycosylated and monoglycosylated isoform was higher than that of typical BSE isolates and case 2 was strongly labeled with antibody P4, which is consistent with a higher molecular mass. Sequencing of the prion protein gene of both BSE-positive animals revealed that the sequences of both animals were within [corrected] the range of the prion protein gene sequence diversity previously reported for cattle.  相似文献   

17.
Chronic wasting disease   总被引：10，自引：0，他引：10  
Chronic wasting disease (CWD) is a unique transmissible spongiform encephalopathy (TSE) of mule deer (Odocoileus hemionus), white-tailed deer (O. virginianus), and Rocky Mountain elk (Cervus elaphus nelsoni). The natural history of CWD is incompletely understood, but it differs from scrapie and bovine spongiform encephalopathy (BSE) by virtue of its occurrence in nondomestic and free-ranging species. CWD has many features in common with scrapie, including early widespread distribution of disease-associated prion protein (PrP(d)) in lymphoid tissues, with later involvement of central nervous system (CNS) and peripheral tissues. This distribution likely contributes to apparent efficiency of horizontal transmission and, in this, is similar to scrapie and differs from BSE. Clinical features and lesions of CWD are qualitatively similar to the other animal TSEs. Microscopically, marked spongiform lesions occur in the central nervous system (CNS) after a prolonged incubation period and variable course of clinical disease. During incubation, PrP(d) can be identified in tissues by antibody-based detection systems. Although CWD can be transmitted by intracerebral inoculation to cattle, sheep, and goats, ongoing studies have not demonstrated that domestic livestock are susceptible via oral exposure, the presumed natural route of exposure to TSEs. Surveillance efforts for CWD in captive and free-ranging cervids will continue in concert with similar activities for scrapie and BSE. Eradication of CWD in farmed cervids is the goal of state, federal, and industry programs, but eradication of CWD from free-ranging populations of cervids is unlikely with currently available management techniques.  相似文献   

18.
A food-borne origin of the transmission of bovine spongiform encephalopathy (BSE) to cattle is commonly assumed. However, the fate of infectious prion protein during polygastric digestion remains unclear. It is unknown at present, whether infectious prion proteins, considered to be very stable, are degraded or inactivated by microbial processes in the gastrointestinal tract of cattle. In this study, rumen and colon contents from healthy cattle, taken immediately after slaughter, were used to assess the ability of these microbial consortia to degrade PrP(Sc). Therefore, the consortia were incubated with brain homogenates of scrapie (strain 263K) infected hamsters under physiological anaerobic conditions at 37 degrees C. Within 20 h, PrP(Sc) was digested both with ruminal and colonic microbiota up to immunochemically undetectable levels. Especially polymyxin resistant (mainly gram-positive) bacteria expressed PrP(Sc) degrading activity. These data demonstrate the ability of bovine gastrointestinal microbiota to degrade PrP(Sc) during digestion.  相似文献   

19.
The brains of 26 Bavarian bovines clinically suspected of bovine spongiform encephalopathy (BSE) were the subject of a neuropathological evaluation containing histopathology and immunohistochemistry. Six animals tested positive for BSE. In these six brains severe histological lesions that correlated with previous reports from the United Kingdom were observed. Immunohistochemistry with prion protein (PrP(Sc)), glial fibrillary acidic protein (GFAP) and synaptophysin were conducted on the mid-brain containing the red nucleus. All BSE-positive brains stained positively for PrP(Sc), and no plaques were observed. The BSE-affected brains showed a substantially more intense staining pattern for GFAP in comparison with the control groups, some of which were diagnosed with severe neuropathological disorders. Synaptophysin staining on BSE-positive brains was substantially reduced in the neuropil of the mid-brain, especially in the red nucleus. Twenty animals tested negative for BSE. The most common diagnoses were listeriosis, viral infections of unknown aetiology, brain oedema and hypomagnesaemia. These disorders may represent the most important clinical differential diagnoses for BSE in Bavaria.  相似文献   

20.
Between 2001 and 2010, 244 clinically suspected cases of bovine spongiform encephalopathy (BSE) were reported in Italy. This report summarizes the neuropathological findings in cattle displaying clinical signs consistent with a diagnosis of BSE. All animal specimens were submitted for confirmatory testing; samples testing negative underwent neuropathological examination to establish the differential diagnosis. Immunohistochemistry for scrapie prion protein (PrPSc) at the level of frontal cortex was carried out to exclude atypical BSE. Neuropathological changes were detected in 34.9% of cases; no histological lesions were found in 52.3% of subjects; 12.8% of samples were found unsuitable for analysis. BSE was detected in one case, but no cases of atypical BSE were observed. This study identified the diseases most commonly encountered in the differential diagnosis of BSE; furthermore, it demonstrated that the surveillance system is necessary for monitoring neuropathological disease in cattle and for the detection of BSE cases.  相似文献   

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