Early infiltration and ~5× increase in cell number of Sendai virus specific CD8 T cells into the lungs of flu infected mice (day 4 post flu). Flu specific [nucleoprotein (NP) and polymerase acidic protein (PA)] CD8 T cell responses were unaltered, and early recruitment of memory cells was from migration of cells from other anatomical sites. When the sequence of infection was reversed, early infiltration and ~4× increase of flu specific memory CD8s occurred at day 4 post Sendai virus infection. Here, CD8A is linked to infection.