Asthmatic mice are highly resistant to influenza A virus challenge.

<p>(<b>A</b>) The general experimental procedure used in this study. Mice were first sensitized to OVA by two i.p. injections, followed by i.n. OVA treatment for 5 consecutive days to induce asthma. Control non-asthmatic mice received PBS only. Asthmatic and non-asthmatic mice were challenged i.n. with PR8 or CA04 influenza A virus at different time points after the last OVA treatment. (<b>B</b> and <b>C</b>) At day 7 after the last PBS or OVA treatment, asthmatic and non-asthmatic mice were infected with either 4, 40 or 400LD₅₀ of CA04 influenza virus (8 mice/group). Infected mice were monitored for survival (B) and weight loss (C). (<b>D</b> and <b>E</b>) Groups of non-asthmatic and asthmatic mice were challenged with either egg-grown PR8 strain (2x10³ PFU) (D) or MDCK grown CA04 virus (6x10⁴ TCID₅₀) (E). Infected mice were monitored for 20 days for survival (5 mice/group). (<b>F</b>) A mouse model of HDM-induced asthma. (<b>G</b> and <b>H</b>) HDM-induced asthmatic and non-asthmatic mice were i.n. challenged with CA04 virus either 1, 2, or 3 weeks following HDM challenge. Weight loss (<b>G</b>) and survival (<b>H</b>) were monitored for 20 days (5 mice/group). *P<0.05; **P<0.01; ***P<0.001.