No correlation between Torque Teno virus viral load and BK virus replication after kidney transplantation

Assessment of the intensity of immunosuppression in transplant recipients to estimate the risk of rejection and infection is not entirely satisfactory at the present time. Determination of Torque teno virus (TTV) viral load appears to be a promising tool in this setting.

We evaluated the level of replication and kinetics of TTV during the first three months after kidney transplantation compared to BK virus replication.

In a retrospective cohort of 116 renal transplant recipients, TTV viral load gradually increased during the first three months post-transplantation with no significant difference or discriminatory threshold between patients with and without BK virus replication. However, the level of TTV replication appeared to be indirectly related to the risk of BK virus replication, particularly according to the induction treatment used (antithymocyte globulin: ATG or basiliximab). Among patients receiving ATG, those receiving cyclosporine had significantly lower TTV viral loads (p < 0.01) with threefold lower reactivation of BKPyV (13 vs 37%) 3 months post-transplantation. Similarly, among the women in our cohort, TTV viral load was significantly higher in women receiving ATG (6.58 ± 1.57 versus 4.62 ± 2.0 log₁₀ copies/mL for basiliximab: p < 0.01), also with threefold higher BKPyV reactivation frequencies (40 vs 13,3%).

The multiparametric variation of TTV viral load does not appear to be individually appropriate for the early detection or monitoring of possible post-transplant BKPyV virus reactivation in renal transplant recipients.