1. Cellular Immunology Laboratory, National Institute for Infectious Diseases “L. Spallanzani” I.R.C.C.S., Rome, Italy.
2. Clinical Department, National Institute for Infectious Diseases “L. Spallanzani” I.R.C.C.S., Rome, Italy.
3. Virology Laboratory, National Institute for Infectious Diseases “L. Spallanzani” I.R.C.C.S., Rome, Italy.