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Early atypical cases of scrapie in UK sheep

Research output: Contribution to journalMeeting abstract

Original languageEnglish
Pages (from-to)63
Number of pages1
JournalPrion
Volume8
Issue numberSuppt
Publication statusPublished - May 2014
EventPrion 2014 - Trieste, Italy, United Kingdom
Duration: 24 May 201430 Jun 2014

Abstract

Atypical scrapie was first discovered in clinically affected sheep in Norway in 1998. It is distinguishable from classical natural scrapie by brain pathology in cerebellum rather than medulla, and by the biochemistry of PrPSc which in atypical scrapie is much less proteinase K resistant but which also has, on Western blots, a characteristic low molecular weight band of varying size estimate of ~8 to 12kD which is absent in classical scrapie. Since 1998, cases similar to Nor98 and with a tendency to occur in older animals, have been identified throughout Europe, including the UK, mainly through the process of active surveillance of asymptomatic sheep. Atypical scrapie occurs in sheep with PRNP genotypes considered to be resistant to classical scrapie such as those with AHQ and ARR alleles, and also with the influence of codon 141 such that genotypes including the AF141RQ allele are more susceptible than those with AL141RQ. Incidence of atypical scrapie is low but persistent and as a result of the measures taken to control classical scrapie in UK and EU, the relative incidence of atypical scrapie has increased to 95% and 27% respectively of all scrapie notifications (European Commission annual report, 2010).
It was originally not certain whether atypical scrapie was a newly emerging TSE disease or whether this form of scrapie had been prevalent in flocks for much longer and only being identified because of increased and improved surveillance methods. As a result of tissue archive searches, we have previously reported that atypical scrapie had been occurring as early as 1989 and the UK Veterinary Laboratories Agency reported a case from 1987. However we sought to take advantage of the Neuropathogensis Unit (NPU) sheep tissue archive (now stored at The Roslin Institute) which has samples dating back to the 1960s to try to find even earlier examples of atypical scrapie to establish whether there had been any change in its phenotype over the decades of its known existence in UK sheep. Immunohistochemistry and Western blotting studies revealed a small number of candidate atypical cases from the 1970s and 1980s which were further strain typed in tg338 mice. Most were confirmed as similar to Nor98, however one case dating from 1972 shows evidence for a very unusual and possibly a mixed classical/atypical infection.

    Research areas

  • prion, SCRAPIE AGENT, atypical scrapie

Event

Prion 2014

24/05/1430/06/14

Trieste, Italy, United Kingdom

Event: Conference

ID: 16991266