The expansion of the γδ T lymphocyte subset during CMV infection is accompanied by a very specific phenotypic change, including the acquisition of markers indicative of cytotoxic activity (perforin+, granzyme+) and of terminal effector differentiation characterized by the loss of CD27 and presence of CD45RA expression, (CD27−, CD45RA+) [24, 25] so called T effector/memory expressing CD45RA (TEMRA) phenotype. Here, CD27 is linked to cytomegalovirus infection.