1. AgResearch; Wallaceville Animal Research Centre; PO Box 40063 Upper Hutt New Zealand
2. Animal Health Board; Ruakura Research Centre; Hamilton New Zealand
3. Veterinary Sciences Division; Department of Agriculture and Rural Development for Northern Ireland; Belfast BT4 3SD
4. Department of Bacterial Diseases; Veterinary Laboratories Agency- Weybridge; Addlestone KT15 3NB
5. Department of Infectious Disease Immunology; Statens Serum Institut; Copenhagen Denmark