1. Laboratory of Experimental Immunology, Institute of Microbiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
2. Hellenic Pasteur Institute, Ampelokipi, Athens, Greece.
3. Institute of Biology and Immunology of Reproduction, Bulgarian Academy of Sciences, Sofia, Bulgaria.
4. National Reference Laboratory of Immunology, National Center of Infectious and Parasitic Diseases, Sofia, Bulgaria.
5. Immunology Research Group, Hungarian Academy of Sciences, Budapest, Hungary.
6. National Institute of Immunology, Sofia, Bulgaria.