1. Cellular Immunology Laboratory, National Institute for Infectious Diseases “L. Spallanzani”, IRCCS, Rome, Italy
2. Department of Haematology, Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
3. National AIDS Center, Division of Pathogenesis of Retroviruses, Istituto Superiore di Sanità, Rome, Italy