1. Virology Unit; Department of Translational Medicine; Medical School of Novara; Via Solaroli 17 28110 Novara Italy
2. Department of Public Health and Pediatric Sciences; Medical School of Turin; Turin Italy
3. Division of Virology; Department of Pathology; University of Cambridge; Cambridge U.K
4. Department of Dermatology; Leiden University Medical Center; Leiden the Netherlands
5. DDL Diagnostic Laboratory; Rijswijk the Netherlands