The kinetics of Torque Teno virus plasma load following calcineurin inhibitor dose change in kidney transplant recipients

Torque Teno virus (TTV) is nonpathogenic, highly prevalent, and reflects the immune status of its host. Thus, TTV plasma load was suggested for the guidance of immunosuppression post solid organ transplantation. The present study was designed to determine the kinetics of TTV following changes in calcineurin inhibitor (CNI) dose. A total of 48 adult recipients of a kidney graft transplanted at the Medical University of Vienna between 2018 and 2019 with isolated changes in CNI dose were selected from the prospective TTV-POET trial. TTV plasma load was quantified by in-house PCR. At Day 30 following CNI dose adaptation (median 33% of daily dose) no changes in TTV load were noted. However, at Day 60, following CNI dose reduction a lower TTV load of 6.4 log(10) c/mL (median; interquartile range [IQR] 4.9-8.1) compared with the baseline of 7.1 log(10) c/mL (IQR 5.3-8.9) was noted (p=0.001); there was also a trend toward a higher TTV load following CNI increase (6.6 log(10) c/mL, IQR 4.1-9.7 vs. 5.2 log(10) c/mL, IQR 4.5-6.8; p=0.09). The data suggested that TTV load changes become noticeable only 2 months after CNI dose adaptation, which might be the ideal time point for TTV load monitoring.