1. Veterinary Laboratories Agency; New Haw, Addlestone Surrey KT15 3NB
2. Veterinary Laboratories Agency; Rougham Hill, Bury St Edmunds Suffolk IP33 2RX
3. Department of Microbiology; University of Barcelona; Barcelona E-08028 Spain
4. National Veterinary Institute; Uppsala Sweden
5. Centre for Hepatology; Royal Free and University College Medical School; University College London; London NW3 2PF