PA-X reduces activation of a TLR7-independent pathway. Wild-type and Tlr7−/− mice were infected with 50,000 pfu of PR8 WT, PR8 FS or mock infected via the intranasal route. Mice were weighed every 24 h and sacrificed 48 h.p.i. (A) Weight loss in mice infected with PR8 WT and PR8 FS. Data are represented as mean weight loss ± s.e.m. (B) Levels of Ifnb1 and Ifna4 mRNA in the lung were measured by qRT-PCR. (C) Levels of the IAV M RNA were measured by qRT-PCR. Data are represented as expression relative to the housekeeping gene Gapdh ± s.e.m. Data in (A–C) are from 4 (mock) and 10–11 (infected) mice per group mice per group, pooled from three independent experiments. *P ≤ 0.05, ***P ≤ 0.001, ns not significant; two-way ANOVA.