1. Division of Molecular Biology; Institute for Animal Health, Pirbright Laboratory, Ash Road, Pirbright; Surrey GU24 0NF
2. Institut für Pathologie; Tierärztliche Hochschule Hannover; Bünteweg 17 D-30559 Hannover Germany
3. Veterinary Laboratories Agency - Winichester; Itcheni Abbas, Winchester Hampshire S021 1BX
4. The Larches, Camrpsea Ash, Woodbridge; Suffolk P1 3 OPH