1. Department of Oral and Maxillofacial Diseases, University of Helsinki, FI-00290 Helsinki, Finland
2. Department of Oral and Maxillofacial Diseases, Helsinki University Hospital and University of Helsinki, FI-00290 Helsinki, Finland
3. Department of Pathology, University of Helsinki and Helsinki University Hospital, FI-00014 Helsinki, Finland
4. Department of Oral Pathology and Radiology, University of Turku, FI-20520 Turku, Finland
5. Division of Periodontology, Department of Dental Medicine, Karolinska Institute, SE-17177 Stockholm, Sweden
6. Department of Virology, University of Helsinki, FI-00290 Helsinki, Finland
7. Meilahti Infectious Diseases and Vaccine Research Center, MeVac, Helsinki University Hospital and University of Helsinki, FI-00290 Helsinki, Finland