1. Hygiene and Epidemiology section, Department of Translational Research, New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
2. Medical Direction, Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy
3. Virology Unit, Pisa University Hospital, Pisa, Italy
4. Retrovirus Center and Virology Section, Department of Translational Research, New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy