Veronica Di Cristanziano

Background Immune recovery following allogeneic hematopoietic stem cell transplantation (allo‐HSCT) decisively influences the occurrence of opportunistic infections, one of the leading causes of death among this group of patients. Yet, today, there are no laboratory parameters mirroring immune function sufficiently. Torque teno virus (TTV) has already proven itself as a functional immune marker in other settings. Aims In this analysis, we investigated whether monitoring of TTV‐DNA load in whole blood is able to provide additional information on the capacity of the immune system to control cytomegalovirus (CMV) replication in allo‐HSCT recipients. Methods Whole blood samples from 59 patients were collected upon allo‐HSCT (between Day −7 and +10), on Day +14, +21, +28, +56, +90, and +365 post‐transplant. TTV‐DNA loads and other relevant clinical information were correlated with the risk of CMV infections or reactivations, defined by evidence of viral replication in blood. Results CMV serostatus of the recipient and a TTV load below 1000 copies/mL upon allo‐HSCT were significantly associated with an increased incidence of CMV infection or reactivation. Conclusions Quantification of TTV load in the early phase of allo‐HSCT procedure could provide additional information in order to identify patients at risk for CMV infection or reactivation.