1. Department of Medical Microbiology, Faculty of Medicine, Medical University of Sofia, Sofia, Bulgaria
2. Department of Genetics, Sofia University “St. Kliment Ohridski”, Sofia, Bulgaria
3. Department of Medical Chemistry and Biochemistry, Molecular Medicine Center, Faculty of Medicine, Medical University of Sofia, Sofia, Bulgaria
4. Department of Microbiology, Military Epidemiology and Hygiene, Military Medical Academy, Sofia, Bulgaria