1. Institute of Veterinary Medicine, University of Goettingen, Göttingen, Germany
2. Department of Obstetrics and Gynecology, University Medical Center Freiburg, Freiburg, Germany
3. Chronix Biomedical, Institute of Veterinary Medicine, Göttingen, Germany
4. Institute of Virology, Philipps University Marburg, Marburg, Germany
5. Institute of Veterinary Pathology, Justus Liebig University Gießen, Gießen, Germany