Immunohistochemical characterisation of classical scrapie neuropathology in sheep

Classical scrapie of sheep and goats was one of the first identified Transmissible Spongiform Encephalopathy (TSE). An immunohistochemical characterisation of classical scrapie neuropathology in sheep has been recently published at the Journal of Comparative Pathology.

This group of diseases is characterized by the accumulation of an abnormal protease resistant conformer of the host-encoded cellular prion protein (PrPc), termed the scrapie-associated PrP (PrPsc), which is also known as the PrPres (resistant PrP) or PrPd (disease-associated PrP).

Neuroinflammation elicited by PrPres (resistant prion protein [PrP]) deposits in the central nervous system (CNS) has been shown to involve cellular and oxidative stress responses in bovine spongiform encephalopathy (BSE) as well as in several murine models of transmissible spongiform encephalopathy (TSE).

Additionally, deregulation of water homeostasis has been suggested to be a further component of the spongiform changes observed in TSEs. The aim of the present study was to characterize the pathogenic events occurring in the CNS of sheep with spontaneously arising classical scrapie.

Brains from seven affected animals and two controls were subject to immunohistochemical and histochemical examinations. Semi-quantitative evaluation of PrPres deposits and spongiform changes throughout the encephalon confirmed that PrPres deposition elicits significant astroglial and microglial reactions, as evidenced by an increase in the number of glial cells and changes in glial cell morphology involving increased expression of vimentin.

The altered expression of metallothioneins 1+2 and heat shock protein 25 (HSP25) suggested that this neuroinflammatory reaction entails cellular and oxidative stress responses. In contrast, there was no change in expression of the membrane-associated water channel aquaporin 1 when PrPres accumulated in the brain.

Expression of aquaporin 1 within the choroid plexus.

This study has been recently published as Immunohistochemical characterisation of classical scrapie neuropathology in sheep. Vidal E, Acín C, Foradada L, Monzón M, Márquez M, Monleón E, Pumarola M, Badiola JJ, Bolea R. J Comp Pathol. 2009 Aug-Oct;141(2-3):135-46. This article is the result of the collaborative work among researchers of the CReSA, Animal Pathology Department, Veterinary Faculty, University of Zaragoza, Animal Tissue Bank of Catalonia (BTAC), Animal Medicine and Surgery Department and Centre de Biotecnologia Animal I Teràpia Gència (CBATEG).

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To contact with the principal investigator of this study at the CReSA:

Dr. Enric Vidal Barba
Spongiform Diseases Unit (PRIOCAT Laboratory, CReSA)
Telephone no.: +34 93 581 45 26
Fax: +34 93 581 44 90
Edifici CReSA. Campus UAB
08193 Bellaterra (Barcelona) España

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