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Experimental transmission of bovine spongiform encephalopathy to European red deer (Cervus elaphus elaphus).

Dagleish MP, Martin S, Steele P, Finlayson J, Sisó S, Hamilton S, Chianini F, Reid HW, González L, Jeffrey M - BMC Vet. Res. (2008)

Bottom Line: Spongiform changes typical of TSE infections were present in brain and accumulation of the disease-associated abnormal prion protein (PrPd) was present in the central and peripheral nervous systems, but not in lymphoid or other tissues.However, the di-, mono- and unglycosylated bands migrated significantly (p < 0.001) further in the samples from the clinically affected deer when compared to BSE infected brains of cattle and sheep.Thus the assessment of risk posed by cervine BSE as a human pathogen or for environmental contamination should await the outcome of ongoing oral challenge experiments.

View Article: PubMed Central - HTML - PubMed

Affiliation: Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Near Edinburgh, EH26 0PZ, UK. mark.dagleish@moredun.ac.uk

ABSTRACT

Background: Bovine spongiform encephalopathy (BSE), a member of the transmissible spongiform encephalopathies (TSE), primarily affects cattle. Transmission is via concentrate feed rations contaminated with infected meat and bone meal (MBM). In addition to cattle, other food animal species are susceptible to BSE and also pose a potential threat to human health as consumption of infected meat products is the cause of variant Creutzfeldt-Jakob disease in humans, which is invariably fatal. In the UK, farmed and free ranging deer were almost certainly exposed to BSE infected MBM in proprietary feeds prior to legislation banning its inclusion. Therefore, although BSE has never been diagnosed in any deer species, a possible risk to human health remains via ingestion of cervine products. Chronic wasting disease (CWD), also a TSE, naturally infects several cervid species in North America and is spreading rapidly in both captive and free-ranging populations.

Results: Here we show that European red deer (Cervus elaphus elaphus) are susceptible to intra-cerebral (i/c) challenge with BSE positive cattle brain pool material resulting in clinical neurological disease and weight loss by 794-1290 days and the clinical signs are indistinguishable to those reported in deer with CWD. Spongiform changes typical of TSE infections were present in brain and accumulation of the disease-associated abnormal prion protein (PrPd) was present in the central and peripheral nervous systems, but not in lymphoid or other tissues. Western immunoblot analysis of brain material showed a similar glycosylation pattern to that of BSE derived from infected cattle and experimentally infected sheep with respect to protease-resistant PrP isoforms. However, the di-, mono- and unglycosylated bands migrated significantly (p < 0.001) further in the samples from the clinically affected deer when compared to BSE infected brains of cattle and sheep.

Conclusion: This study shows that deer are susceptible to BSE by intra-cerebral inoculation and display clinical signs and vacuolar pathology that are similar to those of CWD. These findings highlight the importance of preventing the spread to Europe of CWD from North America as this may necessitate even more extensive testing of animal tissues destined for human consumption within the EU. Although the absence of PrPd in lymphoid and other non-neurological tissues potentially limits the risk of transmission to humans, the replication of TSE agents in peripheral tissues following intra-cerebral challenge is often limited. Thus the assessment of risk posed by cervine BSE as a human pathogen or for environmental contamination should await the outcome of ongoing oral challenge experiments.

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Spongiform change in the obex of the brain from a clinically affected BSE challenged deer. Note the optically empty vacuoles in both neuronal perikarya (black arrows), occasionally containing membranous debris, and also the neuropil (red arrows). Haematoxylin and eosin. Bar = 50 μm.
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Figure 1: Spongiform change in the obex of the brain from a clinically affected BSE challenged deer. Note the optically empty vacuoles in both neuronal perikarya (black arrows), occasionally containing membranous debris, and also the neuropil (red arrows). Haematoxylin and eosin. Bar = 50 μm.

Mentions: Spongiform change characterized by vacuolation of both neuronal perikarya and grey matter neuropil was prominent in the brains of all six clinically affected deer (Figure 1). Optically empty, round or oval vacuoles were present in neuropil while neuronal perikaryonal vacuoles were sometimes loculated and sometimes contained membranous debris. The appearance and distribution of the vacuoles are thus indistinguishable from those of other classical TSEs, including CWD. Lesions predominantly affected the brain stem, thalamus and striate body, as well as the molecular layer of the cerebellum and cerebrocortical layers V and VI.


Experimental transmission of bovine spongiform encephalopathy to European red deer (Cervus elaphus elaphus).

Dagleish MP, Martin S, Steele P, Finlayson J, Sisó S, Hamilton S, Chianini F, Reid HW, González L, Jeffrey M - BMC Vet. Res. (2008)

Spongiform change in the obex of the brain from a clinically affected BSE challenged deer. Note the optically empty vacuoles in both neuronal perikarya (black arrows), occasionally containing membranous debris, and also the neuropil (red arrows). Haematoxylin and eosin. Bar = 50 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2423184&req=5

Figure 1: Spongiform change in the obex of the brain from a clinically affected BSE challenged deer. Note the optically empty vacuoles in both neuronal perikarya (black arrows), occasionally containing membranous debris, and also the neuropil (red arrows). Haematoxylin and eosin. Bar = 50 μm.
Mentions: Spongiform change characterized by vacuolation of both neuronal perikarya and grey matter neuropil was prominent in the brains of all six clinically affected deer (Figure 1). Optically empty, round or oval vacuoles were present in neuropil while neuronal perikaryonal vacuoles were sometimes loculated and sometimes contained membranous debris. The appearance and distribution of the vacuoles are thus indistinguishable from those of other classical TSEs, including CWD. Lesions predominantly affected the brain stem, thalamus and striate body, as well as the molecular layer of the cerebellum and cerebrocortical layers V and VI.

Bottom Line: Spongiform changes typical of TSE infections were present in brain and accumulation of the disease-associated abnormal prion protein (PrPd) was present in the central and peripheral nervous systems, but not in lymphoid or other tissues.However, the di-, mono- and unglycosylated bands migrated significantly (p < 0.001) further in the samples from the clinically affected deer when compared to BSE infected brains of cattle and sheep.Thus the assessment of risk posed by cervine BSE as a human pathogen or for environmental contamination should await the outcome of ongoing oral challenge experiments.

View Article: PubMed Central - HTML - PubMed

Affiliation: Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Near Edinburgh, EH26 0PZ, UK. mark.dagleish@moredun.ac.uk

ABSTRACT

Background: Bovine spongiform encephalopathy (BSE), a member of the transmissible spongiform encephalopathies (TSE), primarily affects cattle. Transmission is via concentrate feed rations contaminated with infected meat and bone meal (MBM). In addition to cattle, other food animal species are susceptible to BSE and also pose a potential threat to human health as consumption of infected meat products is the cause of variant Creutzfeldt-Jakob disease in humans, which is invariably fatal. In the UK, farmed and free ranging deer were almost certainly exposed to BSE infected MBM in proprietary feeds prior to legislation banning its inclusion. Therefore, although BSE has never been diagnosed in any deer species, a possible risk to human health remains via ingestion of cervine products. Chronic wasting disease (CWD), also a TSE, naturally infects several cervid species in North America and is spreading rapidly in both captive and free-ranging populations.

Results: Here we show that European red deer (Cervus elaphus elaphus) are susceptible to intra-cerebral (i/c) challenge with BSE positive cattle brain pool material resulting in clinical neurological disease and weight loss by 794-1290 days and the clinical signs are indistinguishable to those reported in deer with CWD. Spongiform changes typical of TSE infections were present in brain and accumulation of the disease-associated abnormal prion protein (PrPd) was present in the central and peripheral nervous systems, but not in lymphoid or other tissues. Western immunoblot analysis of brain material showed a similar glycosylation pattern to that of BSE derived from infected cattle and experimentally infected sheep with respect to protease-resistant PrP isoforms. However, the di-, mono- and unglycosylated bands migrated significantly (p < 0.001) further in the samples from the clinically affected deer when compared to BSE infected brains of cattle and sheep.

Conclusion: This study shows that deer are susceptible to BSE by intra-cerebral inoculation and display clinical signs and vacuolar pathology that are similar to those of CWD. These findings highlight the importance of preventing the spread to Europe of CWD from North America as this may necessitate even more extensive testing of animal tissues destined for human consumption within the EU. Although the absence of PrPd in lymphoid and other non-neurological tissues potentially limits the risk of transmission to humans, the replication of TSE agents in peripheral tissues following intra-cerebral challenge is often limited. Thus the assessment of risk posed by cervine BSE as a human pathogen or for environmental contamination should await the outcome of ongoing oral challenge experiments.

Show MeSH
Related in: MedlinePlus