Clinical findings in two cases of atypical scrapie in sheep: a case report

Abstract

Background: Atypical scrapie is a recently recognised form of transmissible spongiform encephalopathy of sheep that differs from classical scrapie in its neuropathological and biochemical features. Most cases are detected in apparently healthy sheep and information on the clinical presentation is limited.

Case presentation: This report describes the clinical findings in two sheep notified as scrapie suspects and confirmed as atypical scrapie cases by immunohistochemistry and Western immunoblotting. Although both sheep displayed signs suggestive of a cerebellar dysfunction there was considerable variation in the individual clinical signs, which were similar to classical scrapie.

Conclusion: Any sheep presenting with neurological gait deficits should be assessed more closely for other behavioural, neurological and physical signs associated with scrapie and their presence should lead to the suspicion of scrapie.

Figure 1

PrP^sc immunolabelling in the spinal tract nucleus of the trigeminal nerve (case 06/008). Fine granular staining of PrP^sc in the neuropil with the rat monoclonal antibody R145 [37].

Figure 2

Western immunoblot of cases 05/377 and 06/008. Samples from 05/377 and 06/008 are shown in duplicate lanes; a diluted sample of case 05/377 was included to show the different bands more clearly. Controls are shown in single lanes and comprise a negative control sample (Suffolk, ARQ/ARQ), a known UK classical scrapie case (Poll Dorset, VRQ/VRQ), a known UK bovine BSE case and a known Nor98 Norwegian ovine scrapie case (Norwegian White, AHQ/AHQ). Molecular mass markers were included at either end of the gel (ECL DualVue, Amersham Biosciences, Little Chalfont, UK). The antibody used to detect PrP^res in the test kit is Sha31 [38].