The association of Torque Teno viral load with CMV and BKV infection in pediatric and adolescent kidney transplant patients.

Background: : Long-term allograft and patient survival after kidney transplantation (KTX) depends on the balance between over- and under-immunosuppression (IS). High levels of IS predispose to opportunistic infections. Plasma load of Torque Teno Virus (TTV), a non-pathogenic highly prevalent Annellovirus, is associated with its hosts immune status, especially after solid organ transplantation. Objectives: : To investigate the association of plasma TTV load and opportunistic viral infections after pediatric KTX. Study design: : This retrospective study includes all pediatric KTX patients followed at the Medical University of Vienna 2014 -2020. PCR for Cytomegalovirus (CMV), Epstein -Barr virus (EBV), BK virus (BKV), and TTV was performed every 4 -8 weeks at routine follow-up visits. Results: : 71 pediatric KTX patients were followed with TTV measurements for a median of 2.7 years. TTV plasma load was associated with CMV DNAemia at the next visit with an OR of 2.37 (95 % CI 1.15 -4.87; p = 0.03) after adjustment for time after KTX and recipient age. For a cut-off of 7.68 log10 c/mL TTV a sensitivity of 100 %, a specificity of 61 %, a NPV 100 %, and a PPV of 46 % to detect CMV DNAemia at the next visit was calculated. TTV plasma loads were also associated with BKV DNAuria and BKV DNAemia at the next visit, but not with EBV DNAemia. Conclusions: : This is the first study to analyse associations between TTV plasma loads and opportunistic viral infections in pediatric KTX. We were able to present a TTV cut-off for the prediction of clinically relevant CMV DNAemia that might be useful in clinical care.