CD8A and cytomegalovirus infection: Furthermore, CMV-infection leads to changes in the CD8+ T-cell pool similar to those observed with aging, including the presence of large fractions of terminally differentiated cells (Almanzar et al., 2005; Chidrawar et al., 2009) and a more skewed and less diverse TCR repertoire (Khan et al., 2002; Nikolich-Zugich, 2008).