FIG 9.
qRT-PCR analysis of cytokine gene expression in the lungs and spleens of chickens infected with wt or PA-X-deficient virus. Groups of nine 4-week-old SPF chickens were infected intranasally with 103.0 EID50 of the indicated viruses. Total RNA was extracted from tissues collected at 12, 24, and 36 h p.i. from three birds of each group. Equal amounts of RNA (1 μg) from each sample were used for qRT-PCR. The expression level of each cytokine gene was normalized to that of the β-actin gene and is presented as the fold change from the expression level in mock-treated birds. Values are means ± SD. *, P < 0.05.