Figure 1.

Volume of viral inoculum is critical for eliciting an age‐dependent mortality during IAV infection. Young (2–4 months of age) and aged (18 months of age) C57BL/6 male (a, b) or female (c, d) mice were infected i.n. with either 20 µL or 40 µL inoculum of virus containing 1 x 10⁴ PFU of PR8 strain IAV, and mortality was monitored. In both sexes, an age‐dependent increase in mortality was only noted with the 40 µL inoculum. *p < 0.05, **p < 0.01 (Gehan–Breslow–Wilcoxon test). n = 10–12/group (males), 10/group (females)