Experimental Oral Transmission of Atypical Scrapie to Sheep

Simmons, Marion; Moore, Jerry D.; Konold, Timm; Thurston, Lisa; Terry, Linda A.; Thorne, Leigh; Lockey, Richard; Vickery, Chris; Hawkins, S. A. C.; Chaplin, Melanie J.; Spiropoulos, John

doi:10.3201/eid1705.101654

Cited by 45 publications

(65 citation statements)

References 37 publications

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“…Data from an oral challenge study in sheep also indicate that very early exposure (within 24 hours of birth) can lead to transmission of the disease, resulting in clinically affected animals displaying a similar clinic-pathological pattern to those observed in natural cases (Simmons et al, 2010). It is probably too early, therefore, to conclude if this is a spontaneous, non-contagious disorder or if it can behave like other TSE agents circulating in small ruminants.…”

Section: Exposure and Transmissionmentioning

confidence: 93%

“…While the contagiousness of AS under natural conditions is still debated, the transmissibility of the AS agent by the intracerebral route is clearly established in both rodent models (transgenic animals overexpressing the ovine PrP gene (Le Dur et al, 2005)) and in sheep (Simmons et al, 2007;Simmons et al, 2010). Data from an oral challenge study in sheep also indicate that very early exposure (within 24 hours of birth) can lead to transmission of the disease, resulting in clinically affected animals displaying a similar clinic-pathological pattern to those observed in natural cases (Simmons et al, 2010).…”

Section: Exposure and Transmissionmentioning

confidence: 99%

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Scientific Opinion on the scrapie situation in the EU after 10 years of monitoring and control in sheep and goats

Hald

Baggesen

2014

EFSA Journal

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To assess the effectiveness of the strategies implemented in the European Union (EU) to control Classical scrapie (CS), epidemiological data have been compared in the context of the efforts in terms of control measures applied over time. Official EU surveillance data and results from questionnaire surveys of EU Member States (MSs) have been used along with case studies. A spatio-temporal description of the occurrence of small ruminants TSEs in MSs in the period 2002-2012 is provided, with a particular focus on CS in sheep. Based on information collected from MSs, the potential effectiveness of breeding programmes for resistance to CS (BP-CS) in the dissemination of resistance into the general sheep population has been assessed for those countries for which the CS trend analysis has been performed. CS in sheep was reported in 17 MSs (average prevalence: 8.7 cases/10 000 tests), with heterogeneous trends and geographical distribution: among the 13 countries reporting a consistent number of cases, the trend analysis shows a statistically significant decreasing trend only for six of them. Variations in the implementation of genetic and non-genetic measures for the control of CS may explain the failure to improve the disease situation in the remaining seven MSs. At a national level, a reduction in CS seems to be linked to better-achieving BP-CSs. Control options applied to CS in sheep and goats indicate that a CS eradication policy that relies solely on the detection of infected flocks by post-mortem testing and subsequent depopulation would be unlikely to succeed. A minimum frequency of the ARR allele in a sheep population above which CS may be expected to fade-out could be estimated for each specific national sheep population. Recommendations for additional/alternative measures to control CS in sheep and goats are formulated. Scrapie situation in the EU EFSA Journal 2014;12 (7):3781 2 SUMMARYFollowing a request from the European Commission (EC), the EFSA Panel on Biological Hazards (BIOHAZ) was asked to deliver a scientific opinion on the scrapie situation in the European Union (EU) after 10 years of monitoring and control in sheep and goats. In particular, in order to evaluate the measures in place and assess the progress accomplished, the EC consulted EFSA to gain a better understanding of the dynamics of the epidemiological situation of Classical scrapie (CS) and Atypical scrapie (AS), and a retrospective analysis of the effectiveness of the control tools encompassed by EU legislation.The opinion provides background information in relation to CS and AS in sheep and goats, including information on the nature of the agents, genetic susceptibility of the hosts, transmission pathways and epidemiology of the diseases.Based on information from the EU TSE surveillance database, CS and AS in sheep and goats in the period 2002-2012 have been analysed to provide a spatio-temporal description of the occurrence of the diseases, after appropriate statistical adjustment accounting for the main known confounding factor...

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Section: Exposure and Transmissionmentioning

confidence: 93%

Section: Exposure and Transmissionmentioning

confidence: 99%

Scientific Opinion on the scrapie situation in the EU after 10 years of monitoring and control in sheep and goats

Hald

Baggesen

2014

EFSA Journal

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“…Nevertheless, oral transmission of atypical scrapie has been recently achieved in AHQ/AHQ sheep (10). In that study, although no detectable PrP Sc was found outside the brain during the preclinical and the clinical stages of the disease, prion infectivity was found in the distal ileum.…”

mentioning

confidence: 97%

Role of Palatine Tonsils as a Prion Entry Site in Classical and Atypical Experimental Sheep Scrapie

Chiocchetti

et al. 2014

J Virol

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“…This simple modification has increased significantly the sensitivity of detection of atypical scrapie during surveillance schemes. Unlike classical scrapie, in atypical scrapie the agent is not distributed in peripheral tissues systematically which, in conjunction with its limited distribution in the obex and widespread distribution in the cerebral and cerebellar cortex, have led to the belief that this TSE occurs sporadically 70,71) . This is supported by epidemiological data indicating that it is not infectious under natural conditions 72) , although it can be transmitted experimentally via the oral route 71) .…”

Section: Atypical Scrapiementioning

confidence: 99%

Pathology of Animal Transmissible Spongiform Encephalopathies (TSEs)

Spiropoulos

Simmons

2017

Food Safety

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Pathology is the study of the structural and functional changes produced by diseases or − more specifically − the lesions they cause. To achieve this pathologists employ various approaches. These include description of lesions that are visible to the naked eye which are the subject of anatomic pathology and changes at the cellular level that are visible under the microscope, the subject of histopathology. Changes at the molecular level which are identified by probes that target specific molecules − mainly proteins that are detected using immunohistochemistry (IHC). As transmissible spongiform encephalopathies (TSEs) do not cause visible lesions anatomic pathology is not applicable to their study. For decades the application of histopathology to detect vacuoles or plaques was the only means of confirming TSE disease. The subsequent discovery of the cellular prion protein (PrP C ) and its pathogenic isoform, PrP Sc , which is a ubiquitous marker of TSEs, led to the production of anti-PrP antibodies, and enabled the development of PrP Sc detection techniques such as immunohistochemistry, Histoblot and PETblot that have evolved in parallel with similar biochemical methods such as Western blot and ELISA. These methods offer greater sensitivity than histopathology in TSE diagnosis and crucially they can be applied to analyze various phenotypic aspects of single TSE sources increasing the amount of data and offering higher discriminatory power. The above principles are applied to diagnose and define TSE phenotypes which form the basis of strain characterisation.

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Experimental Oral Transmission of Atypical Scrapie to Sheep

Abstract: Such transmission results in peripheral tissue infectivity that is not detectable by current surveillance screening methods.

Cited by 45 publications

References 37 publications

Scientific Opinion on the scrapie situation in the EU after 10 years of monitoring and control in sheep and goats

Scientific Opinion on the scrapie situation in the EU after 10 years of monitoring and control in sheep and goats

Role of Palatine Tonsils as a Prion Entry Site in Classical and Atypical Experimental Sheep Scrapie

Pathology of Animal Transmissible Spongiform Encephalopathies (TSEs)

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