# The Effect of Immunosuppressive Treatment on Torque Teno Virus Load in Lung Transplant Recipients: A Preliminary Study

## TL;DR

This study explores how the Torque Teno Virus load changes in lung transplant patients and its potential as a marker for monitoring immunosuppression and organ rejection.

## Contribution

The study introduces TTV load as a potential new parameter for assessing immunosuppression efficacy and organ rejection risk in lung transplant recipients.

## Key findings

- TTV load showed a positive correlation with immunosuppression strength in lung transplant patients.
- TTV copy numbers increased significantly with the duration of immunosuppressive treatment.
- TTV may serve as a useful biomarker for monitoring transplant rejection risk.

## Abstract

After transplantation, systematically monitoring and assessing the risk of transplanted organ rejection is crucial. Current methods involving immunosuppressant monitoring, the assessment of organ function, and biopsies are insufficient for predicting rejection. However, regular determination of torque teno virus (TTV) load after transplantation may prove to be a useful parameter for monitoring immunosuppression efficacy. Therefore, we aimed to evaluate TTV load in patients before and after lung transplantation and the kinetics of TTV growth in relation to immunosuppression strength. We included 14 patients (mean age: 49.4 ± 14.0 years) undergoing lung transplantation and determined TTV copy numbers using the commercial ARGENE TTV-R-GENE kit from BioMerieux from the day of transplantation to 180 days post-transplantation. We also developed an empirical immunosuppression unit scale to calculate immunosuppression strength. We observed an average positive correlation between log10 TTV and immunosuppression strength, with significant increases in log10 TTV depending on the duration of immunosuppression. These results indicate the potential of TTV as a new parameter to assess the possibility of transplanted organ rejection.