Animal spongiform encephalopathies ‐ an update part 1. Scrapie and lesser known animal spongiform encephalopathies

Schreuder, B. E. C.

doi:10.1080/01652176.1994.9694444

Cited by 27 publications

(15 citation statements)

References 57 publications

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“…Transmissible spongiform encephalopathies (TSE), or prion diseases, are fatal neurodegenerative diseases with a very long incubation period which include kuru and Creutzfeld-Jacob disease (CJD) in humans, bovine spongiform encephalopathy (BSE), scrapie in sheep and goats and transmissible mink encephalopathy [1,2]. Accumulation of an abnormal isoform (PrP Sc ) of a normal cellular protein (PrP) in affected host tissues is considered a disease hallmark, and its deposition in tissues correlates with infectivity [3,4].…”

Section: Introductionmentioning

confidence: 99%

Clinical, electroretinographic and histomorphometric evaluation of the retina in sheep with natural scrapie

et al. 2011

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BackgroundThe retina is part of the diencephalon in a peripheral location and may be involved in prion diseases. Retinal function and structural changes were assessed in naturally scrapie-affected red face Manech ewes presenting the classical signs of the disease, and clinically healthy age-matched subjects for controls. Ophthalmic examination was done prior to electroretinography (ERG), which was carried out under conditions that allowed photopic and scotopic activities to be assessed. Histomorphometry of the inner and outer retinal layers was performed post-mortem, and retinas were also examined for evidence of abnormal prion protein (PrPSc) accumulation and glial fibrillary acidic protein (GFAP) upregulation as a marker of gliosis. Scrapie status was determined by examination of brain tissueResultsOcular reflexes and ophthalmoscopy did not reveal any difference between scrapie affected and control animals. Although the light-and dark-adapted ERG responses of both rod-and cone-mediated functions had a similar waveform in scrapie-affected and control sheep, a significant reduction in the amplitude of the ERG a-and b-waves was observed in affected animals compared to controls. These functional alterations were correlated with a substantial loss of cells in the outer nuclear layer (ONL), lengthening and disorganization in photoreceptor segments, and substantial reduction in cellularity and thickness of the inner nuclear layer (INL). The degenerative changes in the INL and ONL were most marked in the central and paracentral areas of the scrapie retinas, and were accompanied in all scrapie retinas by PrPSc deposition in the ganglion cell and synaptic layers. GFAP immunoreactivity was mainly increased in the ganglion cell and inner plexiform layers.ConclusionsNo appreciable fundoscopic changes were observed in the scrapie-affected ewes although reproducible changes in retinal function as measured by ERG were observed in these animals. The alterations in the receptoral and post-receptoral pathways corresponded to the degenerative lesions observed in the ONL and INL of the scrapie retinas. The retinal degeneration was associated with prion protein infectivity which presumably spread via the optic nerve.

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Section: Introductionmentioning

confidence: 99%

Clinical, electroretinographic and histomorphometric evaluation of the retina in sheep with natural scrapie

et al. 2011

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“…The last has occurred in cattle (bovine spongiform encephalopathy), cats, and exotic ungulates kept in zoos and fed on similar material to the cattle. A similar disease has occurred in farmed mink, captive mule deer, and elk 8. There has been no evidence of maternal transmission in any of these epidemics of spongiform encephalopathy.…”

Section: Pattern Of Occurrence Of Spongiform Encephalopathy In Speciementioning

confidence: 87%

“…Many recent publications perpetuate the view that spongiform encephalopathy in sheep (and therefore potentially in other species) is maintained largely by maternal transmission 6 7 8. The source papers (see below) on which this claim is based were published in the 1960s, when nothing was known of the molecular genetics of scrapie or the molecular pathogenesis of spongiform encephalopathy and the occasional familial occurrence of the only other endemic spongiform encephalopathy (Creutzfeldt-Jakob disease in humans) was perceived but poorly understood.…”

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confidence: 99%

The myth of maternal transmission of spongiform encephalopathy

Ridley¹,

Baker

1995

BMJ

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It has long been accepted that the pattern of occurrence of scrapie-the form of spongiform encephalopathy associated with sheep-is determined mainly by maternal transmission, and this view has had a profound influence on policy decisions in the control of bovine spongiform encephalopathy and on public concern over the risk to human health from this disease. The occurrence of maternal transmission is, however, not predicted by modern knowledge ofthe aetiology of spongiform encephalopathy, and even though claims ofmaternal transmission have been reiterated frequently in the literature, re-examination ofthe source data reveals that these data are extremely scanty, unreplicated, and probably subject to ascertainment bias. The probability of maternal transmission of spongiform encephalopathy in any species should be viewed with the greatest scepticism.

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“…Scrapie , which is a progressive and fatal neurological disease of sheep (and very rarely of goats), has been present in Europe for more than two centuries, and has been recorded in various countries and continents (11). It owes its descriptive name to the phenomenon that in some cases the infected animals scrape off their wool presumably due to intense itching.…”

Section: Animal Diseasesmentioning

confidence: 99%

Prion diseases. An overview

Dalsgaard

2002

APMIS

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Prion disease is the new designation of a group of spongiform encephalopathies, all invariably fatal, which show similar clinical and neuropathological changes. They comprise a range of distinct diseases in both animals and man, and spontaneous, hereditary and transmissible forms are recognized. Until the sudden occurrence in the mid‐1980s of an epizootic of a formerly unknown disease, popularly named ‘mad cow disease’, in cattle in the UK, very little attention had been paid to these rather obscure diseases. Concurrently it was asserted that the disease‐causing agent appeared to be a ubiquitous mammalian brain constituent, and the disease mechanism a conformational change of its structure. These events have not only led to a new understanding of these extraordinary diseases, but have also provided insight into both neurodegeneration and disease mechanisms at the molecular level. Moreover, in 1997 the prion concept earned its originator the second Nobel price for medicine within this scientific field. In this introduction and overview of prion diseases, historical and philosophical perspectives are presented along with descriptions of the diseases in both animals and man. Epidemiology, genetics and transmissibility are also covered.

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Animal spongiform encephalopathies ‐ an update part 1. Scrapie and lesser known animal spongiform encephalopathies

Cited by 27 publications

References 57 publications

Clinical, electroretinographic and histomorphometric evaluation of the retina in sheep with natural scrapie

Clinical, electroretinographic and histomorphometric evaluation of the retina in sheep with natural scrapie

The myth of maternal transmission of spongiform encephalopathy

Prion diseases. An overview

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