Renal transplant candidates who have CMV-specific, CD8+ T-cells, are CMV-seropositive and carry HLA-A1 and/ or HLA- A2 alleles have a high probability to maintain this type of immunity during the three first months after the transplant, despite induction immunosuppressive therapy (thymoglobulin).

Inclusion Criteria:

1. Renal transplant recipients with CMV-positive serology.
2. Patients with pre-transplant, CMV-specific CD8+ T cell-mediated immunity, i.e. IFNγ levels ≥0.2 UI/mL (QF-CMV Reactive).
3. Adults over 18 years of age.
4. Patients receiving induction therapy with thymoglobulin (at least a cumulative dosage of 1mg/kg).
5. Patients receiving prophylaxis with valganciclovir (900 mg/day, adjusted to kidney function) until day 90 after transplant.
6. Patients who signed an informed consent

Exclusion Criteria:

1. Multivisceral transplantation, including pancreas-kidney transplantation.
2. HIV infected patients.
3. Patients who cannot comply with the monitoring protocol.

Patients who are candidates for renal transplant and who fulfil the clinical criteria established by the participating institutions to receive induction immunosuppressive therapy. Participating institutions may include centers from the Spanish Network for Research in Infectious Diseases (REIPI, Transplantation Program) as well as other centers outside the network.