title: A retrospective immunohistochemical study reveals atypical scrapie has existed in the United Kingdom since at least 1987.
abstract: Atypical scrapie is a relatively recent discovery, and it was unknown whether it was a new phenomenon or whether it had existed undetected in the United Kingdom national flock. Before 1998, the routine statutory diagnosis of transmissible spongiform encephalopathy (TSE) in sheep relied on the presence of TSE vacuolation in the brainstem. This method would not have been effective for the detection of atypical scrapie. Currently, immunohistochemistry (IHC) and Western blot are commonly used for the differential diagnosis of classical and atypical scrapie. The IHC pattern of PrPd deposition in atypical scrapie is very different from that in classical scrapie using the same antibody. It is thus possible that because of a lack of suitable diagnostic techniques and awareness of this form of the disease, historic cases of atypical scrapie remain undiagnosed. Immunohistochemistry was performed on selected formalin-fixed, paraffin-embedded (FFPE) blocks of ovine brain from the Veterinary Laboratories Agency archives that were submitted for various reasons, including suspect neurological disorders, between 1980 and 1989. It was found that PrPd deposits in a single case were consistent with atypical scrapie. A method was developed to obtain a PrP genotype from FFPE tissues and was applied to material from this single case, which was shown to be AHQ/AHQ. This animal was a scrapie suspect from 1987, but diagnosis was not confirmed by the available techniques at that time.
authors.affiliation: Department of Pathology, Veterinary Laboratories Agency-Weybridge, Woodham Lane, New Haw, Addlestone, Surrey, UK. p.webb@vla.defra.gsi.gov.uk
authors.forename: Paul R
authors.initials: PR
authors.lastname: Webb
authors.forename: Linda
authors.initials: L
authors.lastname: Powell
authors.forename: Margaret
authors.initials: M
authors.lastname: Denyer
authors.forename: Sarah
authors.initials: S
authors.lastname: Marsh
authors.forename: Colin
authors.initials: C
authors.lastname: Weaver
authors.forename: Marion M
authors.initials: MM
authors.lastname: Simmons
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Johns
authors.forename: John
authors.initials: J
authors.lastname: Sheehan
authors.forename: Peter
authors.initials: P
authors.lastname: Horsfield
authors.forename: Chris
authors.initials: C
authors.lastname: Lyth
authors.forename: Christina
authors.initials: C
authors.lastname: Wilson
authors.forename: Ann
authors.initials: A
authors.lastname: Long
authors.forename: Saira
authors.initials: S
authors.lastname: Cawthraw
authors.forename: Ginny C
authors.initials: GC
authors.lastname: Saunders
authors.forename: Yvonne I
authors.initials: YI
authors.lastname: Spencer
mesh_terms: D000818:Animals; D001479:Basal Ganglia / Q000473:pathology; D002531:Cerebellum / Q000473:pathology; D054022:Cerebrum / Q000473:pathology; D015511:Goat Diseases / Q000453:epidemiology / Q000473:pathology; D006041:Goats; D012189:Retrospective Studies; D012608:Scrapie / Q000453:epidemiology* / Q000473:pathology*; D012756:Sheep; D014276:Trigeminal Nerve / Q000473:pathology; D006113:United Kingdom / Q000453:epidemiology