• ATG
• Basiliximab
• immune system
• solid organ transplantation
• TTV

TTV is a single stranded circular DNA virus of about 3.8 kb that was first found in a Japanese patient with non-A-E hepatitis. TTV is ubiquitous worldwide, it infects about 80% of adults regardless race, gender, and geographic region. The virus may persist for years in the infected host, with plasma levels ranging from 102 to 108 copies of viral DNA\ml. At the moment, no human disease has been clearly associated with this virus; many virologists considered TTV as an orphan virus, commonly present in humans where it represents a large part of virome. Recent evidences have demonstrated that TTV viremia is present at higher levels in patients with compromised immune system than in ones with normal immunity. Starting from these observations, the aim of the present study was to evaluate the relationship between TTV loads and status of immune system in patients with solid organ transplantation over time. TTV viremia was quantified by using an universal real-time PCR designed on a region of the viral genome highly conserved among all TTVs known, plasma samples obtained before and at selected time points post-transplant were tested, and the levels of TTV were correlated with several parameters measured in the course of clinical follow-up (i.e. type of drug therapy administered, donor’s characteristics, number of transplant, CMV reactivation, etc…). The results obtained demonstrate that an impaired immune system promotes TTV replication and consequently induces increased levels of viremia in transplant patients In conclusion, the study demonstrates that measuring TTV plasma levels over time might be useful to define the functionality of immune system in the infected host and help in determining when the patient’s immune system has recovered a good level of activity.