1 University of Turin, Microbiology and Virology Unit; Azienda Ospedaliera Città della Salute e della Scienza di Torino, Via Santena 9, 10126 Turin, Italy.
2 University of Rome "La Sapienza", Department of Molecular Medicine, Piazzale Aldo Moro, 00185 Rome, Italy.
3 University of Basel, Transplantation and Clinical Virology, Division Infection Diagnostics, Department Biomedicine (Haus Petersplatz), Petersplatz 10, CH-4003 Basel, Switzerland ; Infectious Disease and Hospital Epidemiology, University Hospital Basel, Petersgraben 4, CH-4031 Basel, Switzerland.