1. Section of Microbiology, Department of Biotechnology, University of Siena, 53100 Siena, Italy
2. Clinical Microbiology and Virology Unit, Modena University Hospital, 41100 Modena, Italy
3. Section of Infectious Diseases, Department of Biotechnology, University of Siena, 53100 Siena, Italy
4. Bone Marrow Transplantation Unit, Modena University Hospital, 41100 Modena, Italy
5. Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena, 00161 Rome, Italy
6. Clinical Microbiology and Virology Unit, Siena University Hospital, 53100 Siena, Italy