Long-term outcomes in kidney transplantation remain a significant challenge, as complications such as donor-specific antibodies (DSA), antibody-mediated rejection, infections, and cancer increasingly threaten graft and patient survival over time. The development of non-invasive biomarkers to guide the management of therapeutic immunosuppression beyond the first year post-transplantation is therefore a crucial unmet need. Torque Teno Virus (TTV), a non-pathogenic virus with a high prevalence worldwide, has emerged as a promising biomarker in this context. Its replication inversely reflects immune control by T cells, correlating with the depth of therapeutic immunosuppression. Additionally, its slow replication kinetics make TTV DNAemia a useful marker for evaluating patient adherence to immunosuppressive treatments. The TAOIST study tests whether longitudinal monitoring of TTV DNAemia every three months, starting from the second year after transplantation, can guide the personalization of immunosuppressive therapy. The primary endpoint is the time to the first occurrence of complications linked to inadequate immunosuppression, including dnDSA, biopsy-proven rejection, infection, cancer, or graft loss. Secondary objectives include evaluating the acceptability of TTV DNAemia among healthcare professionals and assessing its cost-effectiveness compared to standard care. An ancillary objective examines the link between TTV DNAemia and the immunosuppressant possession ratio (IPR) to explore its potential as a marker of treatment adherence.