Quantiferon CMV to Identify Treatment Need for Asymptomatic CMV Infection After Solid Organ Transplant (QUANTIFOT)

Context. Solid organ transplant (SOT) recipients are at high risk of opportunistic infections, particularly due to cytomegalovirus (CMV). Regarding CMV infection after transplantation, two approaches are possible: either antiviral prophylaxis for several months, followed by monitoring of blood CMV viral load (or viremia), or immediate monitoring of viral load without prophylaxis. In both cases, the detection of a CMV viral load raises a complex question: is antiviral treatment necessary? Indeed, not all viremia leads to CMV disease: some patients spontaneously control their viremia. In order to limit unnecessary treatments, their toxicity and their cost, new tools are needed to identify people at high risk of developing a high viral load or CMV disease. As CMV infection is mainly controlled by cellular immunity, measuring specific anti-CMV T lymphocyte immunity could be an interesting tool for identifying these at-risk individuals. The QuantiFERON-CMV (QF-CMV) test (QuiagenTM, Courtabœuf, France) is an interferon-gamma (IFN-γ) release assay (IGRA), which measures the presence of anti-CMV T lymphocyte immunity. Results from previous retrospective studies suggest that in cases of CMV replication, it may be relevant to base the therapeutic attitude not only on the virological characteristics of this replication, but also on the existence of specific T lymphocyte immunity. The aim of this study is therefore to prospectively assess the contribution of QF-CMV to therapeutic decisions in cases of intermediate CMV viral load (between 1,000 and 15,000 IU/mL). Methods SOT recipients with a detectable blood CMV viral load (CV1) between 1,000 and 15,000 IU/mL without symptoms (fever, organ damage) will be offered participation in the study within 48 hours of detection of this CMV viral load. After inclusion, participants will be immediately sampled for QF-CMV. They will be randomized (2:1) into 2 groups: * An experimental group in which the result of the QF-CMV will be communicated to the doctor in charge; * A control group in which the result is not reported to the doctor in charge. In the experimental group, the recommended attitude will depend on the QF-CMV result: * If positive, the physician in charge will be advised not to introduce antiviral treatment; * If is negative or indeterminate, the physician in charge will be advised to proceed according to the standard of care. He/she will be free to introduce or not the antiviral molecule of his choice. In the control group, the physician in charge will be advised to proceed according to the standard of care, based on current recommendations and local practices. In both groups, as routinely done when a CMV viral load is detected in the blood, this parameter will be checked several times after the 1st detection (V0): * 5 to 12 days after QF-CMV sampling (CV - V2 = D5 to D12) ; * 7 to 14 days after CV2 (CV3 - V3 = D12 to D26) ; * 7 to 14 days after CV3 (CV4 - V4 = D19 to D40). Similarly, blood cell count, kalemia and creatininemia were performed at baseline and then at V2, V3 and V4. The primary endpoint is the rate of uncontrolled infection at 5 to 12 days after QF-CMV sampling (V2), defined as follows: * Blood CMV viral load \>10,000 IU/mL \[4 log\] ; * And/or increase in blood viral load ≥0.5 log IU/mL with CV otherwise \>5000 IU/mL ; * And/or the onset of CMV disease. Conversely, the blood CMV viral load will be considered controlled if its value at V2 does not exceed 10,000 IU/mL \[4 log\] and : * It decreases (regardless of the magnitude of the decrease); * Or increases, but by less than 0.5 log IU/mL ; * or is stable. In the event of uncontrolled infection at V2, the physician in charge should manage the viral load in accordance with current recommendations and local practices (in most cases, antiviral treatment should be introduced if this has not already been done), and continue monitoring at V3 and V4. He will be free to introduce or not the antiviral molecule of his choice. In the event of controlled infection at V2, the physician in charge will be advised not to initiate antiviral treatment if this has not already been done, and to continue monitoring at V3 and V4. The secondary endpoint is the occurrence of an iatrogenic event (hematoxicity or nephrotoxicity) related to antivirals; parameters that may reflect such toxicity (blood cell count, kalemia, creatinin) will be collected at inclusion (V1) and then at the 3 times mentioned above (V2 to V4).