Surprisingly, recent researches highlight a commensal-like function for HCMV in the immunosurveillance of aging cells in immunocompetent hosts: on the one hand, HCMV can be reactivated in senescent fibroblasts, but with low IE1/2 expression and the absence of productive infection, and on the other hand, CD4 CTLs are able to target HCMV-gB antigens to recognize and clear senescent cells [119, 183, 201]. The gene discussed is CD4; the disease is infection.