1. Veterinary Medical Research Institute, Hungarian Academy of Sciences
2. Central Veterinary Institute, H-1581 Budapest, Hungary
3. Institute of Zoology, Fishery Biology and Fish Diseases, Ludwig-Maximilians- Universität, D-80539 Munich, Germany
4. Research Division, Clear Springs Foods, Inc., Buhl, Idaho 83318
5. Institute of Veterinary, Animal and Biomedical Sciences, Massey University, 11222 Palmerston North, New Zealand