Description of the different isolates used in this work.

1French National Institute for Agricultural Research (INRA), Nouzilly, France.2Centro de Investigación en Sanidad Animal– Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (Madrid, Spain).3Veterinary Laboratory Agency (VLA), New Haw. Addlestone, Surrey, UK.4provided by Martin Groschup (Friedrich-Loeffler-Institut), Germany.5National Reference Centre for TSE (ISS Torino).6National Reference Laboratory for Veterinary TSEs (Belgium).7National TSE Reference Laboratory (AFSSA, Lyon, France).8provided by Nora Hunter (IAH, UK).9CJD Resource Centre-National Institute for Biological Standards and Control, South Mimms, Potters Bar, UK.10Institut National de la Santé et la Recherche Médicale (France).