1. Hebrew University of Jerusalem, Faculty of Agriculture, Department of Animal Science, Rehovot, Israel
2. Institute for Animal Health, Compton, Berkshire, United Kingdom
3. Kimron Veterinary Institute, Beit Dagan, Israel
4. Institute for Animal Health, Compton, Berkshire, United Kingdom; and Bioproperties (Australia) Pty Ltd., Ringwood North, Victoria, Australia