This study aim to evaluate the performances of this new assay to predict the risk of CytoMegaloVirus (CMV) reactivation in the colon of UC patients. A new algorithm for the care of Ulcerative Colitis (UC) patients that could be used in all centers, even those without molecular biology lab, could be proposed: in case of a positive QuantiFERON-CytoMegaloVirus (QF-CMV) assay, the immune response protects the patient against Cytomegalovirus (CMV) reactivation and intensification of immunosuppressive therapies should be proposed; at the opposite, a negative QuantiFERON-CytoMegaloVirus (QF-CMV) assay will invite to biopsy in order to detect CytoMegaloVirus (CMV) replication and to treat with ganciclovir when appropriate. This algorithm will preserve invasive biopsies in absence of CytoMegaloVirus (CMV) tissue reactivation.