Expression of IL-17 in trachea in C. baileyi infected chickens. Chickens were orally infected with 1 × 105 oocysts of C. baileyi. Tracheas were isolated from infected and non-infected chickens at the indicated times post-infection and mRNA levels were determined by qPCR (normalized to beta-actin transcript levels). Each bar represents the mean ± SD values (n = 5). *means P < 0.05, **means P < 0.01, ***means P < 0.001.