1. Department of Virology, Eijkman-Winkler Center, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
2. Department of Pediatrics, Division of Infectious Disease, Wilhelmina Children's Hospital, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, The Netherlands
3. Department of Pediatrics, Division of Intensive Care, Wilhelmina Children's Hospital, University Medical Center Utrecht, Lundlaan 6, 3584 EA Utrecht, The Netherlands
4. Laboratory of Medical Microbiology and Immunology, St. Elisabeth Hospital Tilburg, Hilvarenbeekseweg 60, 5022 GC Tilburg, The Netherlands