This showed that although on day 7 p.i. there were more lymphocytes recruited to lungs infected with v-176WT compared with infection with vH1 or v176-NHA, CD3+ T cells were less activated (Fig. 7c, left panel), and this was reflected by a lower level of the activation marker CD69+ on both CD4+ and CD8+ lymphocytes (Fig. 7c, right panel). Here, CD4 is linked to infection.