In addition, we found that characteristics of memory-like NK cells, such as high CD2 expression and low CD161, NKG2A, and PLZF expression (6, 7, 13, 14), were evident early after HCMV infection, suggesting that the epigenetic modification described in memory-like NK cells (6, 7) may take place during the early developmental period. Here, CD2 is linked to cytomegalovirus infection.