There is a transient reduction in the frequency of Flu- and CMV-specific T cells during primary EBV infection. PBMCs were stained with antibodies against CD3, CD4, CD8, and pMHCI tetramers. The graph represents the frequency of Flu (left) and CMV (right) tetramer⁺CD3⁺CD8⁺ T cells before (squares), during (triangles), and after (inverted triangles) acute primary EBV infection (n = 10 for Flu and n = 11 for CMV; paired Student’s t test, P > 0.05 was considered not significant). Horizontal bars indicate the mean.