1. Center for Infectious Disease Control, National Institute for Public Health and the Environment, Bilthoven, the Netherlands
2. Current address: Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
3. Department of Medical Microbiology, University Medical Center Groningen, Groningen, the Netherlands
4. Department of Medical Microbiology, Leiden University Medical Center, Leiden, the Netherlands
5. Department of Viroscience, Erasmus Medical Center, Rotterdam, the Netherlands
6. Department of Virology, University Medical Center Utrecht, Utrecht, the Netherlands
7. Laboratory of Medical Microbiology and Immunology, St Elisabeth Hospital, Tilburg, the Netherlands
8. Department of Medical Microbiology, Academic Medical Center, Amsterdam, the Netherlands