Here, we demonstrate that IFN-α/β-R is expressed on ex vivo isolated CD4+ T cells at similar levels as seen on CD8+ T cells; as type I interferons induce the proliferation of memory CD8+ T cells [59] and are essential for the in vivo clearance of viral infections [30], this suggests that IFN-α/β-R plays a physiological role on CD4+ T cells. This evidence concerns the gene CD4 and viral infectious disease.