FIG 2.

Suppression of the IFN-I response delays invasion of the pleural cavity by strain 1861. Mice were treated with anti-IFNAR1 neutralizing antibody (Ab; open circles) or an isotype control (Iso; closed circles) and challenged i.n. with 10⁷ CFU of either strain 1 or strain 1861. The total number of CFU recovered from lungs (A), the pleural cavity (B), or blood (C) was determined at 6 h or 24 h postchallenge, as indicated. The horizontal broken lines in each strain group indicate the geometric mean number of CFU that were recovered. In panel B, statistical differences were analyzed by a one-tailed unpaired t test using log-transformed values (*, P < 0.05). The single horizontal spotted line indicates the limit of detection (LD). At 6 h, this equates to 10² CFU/lung, 10 CFU/pleural cavity, and 10 CFU/ml blood. At 24 h, it equates to 10² CFU/lung, 2 × 10² CFU/pleural cavity, and 2 × 10² CFU/ml blood. Group sizes were as follows: n = 5 to 6 for strain 1 challenge groups; n = 7 to 8 for blood and lung samples from 6-h strain 1861 challenge groups; n = 7 to 8 for lung samples from 24-h 1861 challenge groups; n = 11 to 12 for all other groups.