By days 5 and 7 of infection, there was a marked difference in gene expression with heightened expression of Mx1, Tlr3, Ifnα2, Ifnαr1, Ifnβ1, and Il-15 detected in aged lung in response to H1N1 (Figure 3A,C,D, Supplemental Table S2). This evidence concerns the gene TLR3 and infection.