1. Department of Veterinary Disease Biology, University of Copenhagen, 4 Stigbøjlen, DK-1870 Frederiksberg C, Denmark
2. Microbiological Diagnostics, German Cancer Research Centre, D-69120 Heidelberg, Germany
3. Professor emeritus, Horsevænget 40, Viby Sjælland, Denmark
4. Mr. Tripkade 51, 3571 SW, Utrecht, The Netherlands
5. Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Laenggass-Strasse 122, CH-3001 Bern, Switzerland