Investigation of Torque Teno Virus Loads as a Marker of Immunosuppression in Pediatric Chronic Renal Failure: A Pilot Study

BACKGROUND: Torque Teno Virus (TTV), family Anelloviridae, is a small, non-enveloped, single-stranded DNA virus that has not been linked with any specific human illness but nevertheless constitutes a major component of the human virome. An association between TTV loads and the immune status of the host with reference to other viral infections, immunosuppression therapy, and acute rejection is reported in adult and pediatric kidney transplant recipients. We sought to investigate the feasibility of TTV as a surrogate marker of the degree of immunosuppression in pediatric kidney transplant patients. METHODS: 185 children attending the Nephrology clinic in Children's Health Ireland at Temple Street were studied over a four-year period from September 2019 until November 2023, ranging from 0 to 17 years of age. Patients were enrolled from pre-transplant undergoing kidney replacement therapy (n = 12), from post-transplant (n = 124) groups, and from patients with chronic renal failure (n = 20) (without kidney replacement therapy), all of which were compared to controls (n = 35). TTV loads were quantified using a standardized TTV R-gene kit. RESULTS: TTV loads were significantly higher compared to controls from 3 months post-transplantation onward (p < 0.001), with the greatest increase observed between 3 and 6 months post-transplantation. Immunosuppression exerted a significant independent effect on TTV loads after adjusting for age (p < 0.001). Overall, females exhibited significantly higher TTV loads than males (p = 0.01). Furthermore, a significant interaction was observed between patient group and gender (p < 0.001). CONCLUSION: These findings suggest that both immunosuppressive status and gender-related factors contribute to TTV kinetics after transplantation and should be considered when interpreting TTV as a biomarker of immune function. Larger studies are required to confirm our findings.