1. Immunity and Infection Division, The Roslin Institute and R(D)SVS, University of Edinburgh, Edinburgh EH25 9RG, UK.
2. Centre for infection and Immunity, 4th Floor Medical Biology Centre, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast BT9 7BL, UK.
3. Division of Veterinary Clinical Sciences, Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush Campus, Roslin, Midlothian EH25 9RG, UK.
4. Department of Food and Environmental Safety, Veterinary Laboratories Agency, Woodham Lane, New Haw, Addlestone, Surrey, KT15 3NB, UK.
5. Laboratory for Foodborne Zoonoses, Public Health Agency of Canada, 1st floor, C.F.I.A. Building, Lethbridge, AB T1J 3Z4, Canada.
6. Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
7. Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, GU2 7XH, UK.