Torque Teno Virus Polymerase Chain Reaction Titer: A Promising Immunometry

Solid-organ transplant is the treatment of choice for all patients with end-stage diseases. Long-term graft function and survival rely on suitable immunosup-pressive treatment to prevent rejection. Besides this desired effect, a reduced immunocompetence in the transplant recipient increases the risk of developing infectious diseases and malignancies. An ideal biomarker should be sensitive, allow early visibility, be accessible in peripheral blood, and be associated with a known mechanism. Torque teno virus or transfusion transmitted virus is a virus that has gained attention as a possible marker of immune function. This virus rarely causes disease in healthy individuals, but torque teno viral load in immunosuppressed patients is shown to be higher than in healthy controls. Replication of torque teno virus is inversely correlated with number and especially functions of T lymphocytes. Torque teno virus could join the current list of predictive biomarkers in transplantation to detect whether the patient is over- or under-immunosuppressed. More studies are needed to confirm or disprove this possibility.