1. Department of Infectious Pathology & Hygiene, Technology and Control of Food of Animal Origin, Faculty of Veterinary Medicine, University of Forestry, Sofia, Bulgaria
2. Department of Obstetrics, Gynecology, Biotechnology of Reproduction & Pathological Anatomy and Biochemistry, Faculty of Veterinary Medicine, University of Forestry, Sofia, Bulgaria
3. Department of Virology and Viral Diseases, National Diagnostic and Research Veterinary Institute, Sofia, Bulgaria
4. Department of Animal Breeding Science, Faculty of Veterinary Medicine, University of Forestry, Sofia, Bulgaria
5. Department of Pathophysiology, Faculty of Medicine, Medical University, Sofia, Bulgaria