In addition, the memory CD4+ T cells maintained their primary activation-dependent Th1 and Tfh bias, as the LCMV(1°)PR8(2°) mice had significantly more LY6C+ Th1-like secondary memory T cells 42 days after influenza infection and the GP(1°)PR8(2°) mice had significantly more FR4+ Tfh-like secondary memory T cells (Fig 6E–6G). Here, CD4 is linked to influenza.