Brief Summary: Solid organ transplant candidates will undergo serological screening for HHV8 at time of listing and transplantation. In the event of a recipient/donor mismatch R-/D+ or in the presence of a seropositive recipient (R+), blood levels of HHV8 DNA will be monitored together with specific IGRA for HHV8.

Detailed Description: Patients on the waiting list for solid organ transplantation will undergo serological screening for HHV8 (lytic and latent antigens) in the pre-transplant phase, both at time of listing and then at the time of transplantation; if seropositivity is found, further investigations will be performed, i.e. blood levels of HHV8 DNA and specific Elispot for HHV8. As for donors, serological testing for HHV8 (lytic and latent antigens) will be performed. AFTER SOLID ORGAN TRANSPLANTATION * Patients found HHV8 seropositive in the pretransplant phase (R +), being at risk of HHV8 reactivation, will be monitored monthly in terms of viremia (HHV8 DNA) and specific IGRA for HHV8 for the first 6 months after transplantation and subsequently every 3 months up to 12 months post transplant. * In case of patients who were found HHV8 seronegative at time of transplantation, donor serology will be evaluated. In case of R-/D+ mismatch, SOT recipients will receive the same monitoring of R + patients (blood levels of HHV8 DNA and specific IGRA for HHV8 monthly for the first 6 months and then every 3 months up to 12 months after transplantation). * With reference to lung transplant patients, in cases of R + or R- / D +, HHV8 DNA will also be searched on the BAL obtained during surveillance bronchoscopies (usually at 3, 6 and 12 months after transplantation).