How to cite this article: Vet. Res. (2008) 39:19
DOI: 10.1051/vetres:2007056

Review

Atypical/Nor98 scrapie: properties of the agent, genetics, and epidemiology

Sylvie L. Benestad¹, Jean-Noël Arsac², Wilfred Goldmann³ and Maria Nöremark<sup>4

1</sup>  National Veterinary Institute, PO Box 8156 Dep., Oslo, Norway
²  Agence Française de Sécurité Sanitaire des Aliments, 31 av. Tony Garnier, 69364 Lyon Cedex 07, France
³  Neuropathogenesis Unit, Roslin Institute, Ogston Bldg, West Mains Rd, Edinburgh, EH9 3JF, UK
⁴  National Veterinary Institute, 75189 Uppsala, Sweden

Received 23 July 2007; accepted 23 October 2007 ; published online 11 January 2008

Abstract - Atypical/Nor98 scrapie cases in sheep were diagnosed for the first time in Norway in 1998. They are now identified in small ruminants in most European countries and represent an increasingly large proportion of the scrapie cases diagnosed in Europe. Atypical/Nor98 scrapie isolates have shown to be experimentally transmissible into transgenic mice and sheep but the properties of the TSE agent involved, like its biological and biochemical features, are so clearly distinct from the agent involved in classical scrapie that they have provided a challenging diagnostic for many years. No strain diversity has yet been identified among the atypical/Nor98 scrapie sample cases. The genetic predisposition of the sheep affected by atypical/Nor98 scrapie is almost inverted compared to classical scrapie, and the exact origin of this sporadic TSE strain is still speculative, but a spontaneous, non-contagious origin, like sporadic Creutzfeldt-Jakob disease in humans, can not be excluded. Further transmission and epidemiological studies are needed to better address this hypothesis.

Key words: atypical scrapie / Nor98 / transmissible spongiform encephalopathies TSE / genetics / epidemiology

Corresponding author: sylvie.benestad@vetinst.no

© INRA, EDP Sciences 2008