1. Institute for Medical Microbiology and Hygiene; University of Regensburg; Regensburg Germany
2. Department of Retrovirology; National Center for Epidemiology; Budapest Hungary
3. RT-Europe Nonprofit Research Center; Mosonmagyarovar Hungary
4. University of Szeged; Faculty of Dentistry, Department of Oral Biology and Experimental Dental Research; Szeged Hungary
5. Division of Virology; National Center for Epidemiology; Budapest Hungary