1. Department of Internal Medicine; Division of Nephrology; University Medical Center Groningen; University of Groningen; Groningen The Netherlands
2. Department of Clinical Virology; University Medical Center Groningen; University of Groningen; Groningen The Netherlands
3. Renal Transplant Unit; Academic Medical Center; University of Amsterdam; Amsterdam The Netherlands
4. Renal Transplant Unit; Department of Nephrology; Leiden University Medical Center; Leiden The Netherlands
5. Department of Epidemiology; University Medical Center Groningen; University of Groningen; Groningen The Netherlands