TABLE 2.

Strain-dependent induction of immune response genes in lungs at 6 h postchallenge with strain 1861 versus strain 1 suggests involvement of the IFN-I response^a

Gene symbol	Strain 1861 vs strain 1
	Fold change	Significance
Crp	6.91	*
Cxcl10	5.11	*
Ifna2	3.69	*
Ifng	6.22	**
Il10	2.22	*
Irf7	2.73	*
Mx1	3.39	*
Stat1	3.50	*

^aAnimals (n = 4 per group) were challenged with 10⁷ CFU of strain 1 or strain 1861 or left unchallenged (“resting”). Lungs were harvested for RNA isolation at 6 h postchallenge, and immune response gene expression was analyzed using mouse innate and adaptive immune response RT² Profiler PCR arrays (cutoff used, fold change ≥ 2). Data represent changes in gene expression in lungs from animals challenged with strain 1861 relative to lungs from animals challenged with strain 1. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ns, not significant (P ≥ 0.05).