When comparing the impact of HCMV infection, in donors of all ages, on the numbers of differentiated T cell subsets [representative donor phenotype staining is shown (Figure 2A)], we observed a significant expansion of the effector memory (TEM—CD27−CD45RA−) population in both CD8+ (Figure 2B) and CD4+ T cells (Figure 2D). This evidence concerns the gene CD4 and cytomegalovirus infection.