FIG 12.
qRT-PCR analysis of cytokine gene expression in the lungs and spleens of ducks infected with wt or PA-X-deficient virus. Groups of nine 6-week-old mallard ducks were infected intranasally with 105.0 EID50 of a recombinant virus or the parental strain. Total RNA was extracted from tissues collected on days 1, 3, and 5 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 GAPDH gene and is presented as the fold change from the expression level in mock-infected ducks. Values are means ± SD. *, P < 0.05.