[1] Natl AIDS Ctr, Ist Superiore Sanita, Viale Regina Elena 299, I-00161 Rome, Italy
[2] San Gallicano Hosp, Rome, Italy
[3] Osped San Raffaele, Milan, Italy
[4] Natl Inst Infect Dis L Spallanzani, Rome, Italy
[5] Univ Roma La Sapienza, Rome, Italy
[6] Univ Urbino, Urbino, Italy