CD8A and cytomegalovirus infection: Frequencies of activated CD8+ T cells correlated with the magnitude of the CMV-specific IFN-γ ELISpot response (Spearman’s rho, P = 6 × 10–8, Figure 2A), suggesting that CMV infection (as defined by a positive CMV-specific T cell response) is associated with CD8+ T cell activation in this infant cohort.