Expression of IFN-γ and IL1-β following infection with S . Gallinarum 9R. Expression of the cytokines IFN-γ (A) and IL1-β (B) in the spleen of Line 72 chickens infected with S. Gallinarum 9R (±SEM). Expression was determined by quantitative reverse-transcription real-time PCR. Data are displayed as the mean fold-change in expression in infected birds (n = 5) in comparison to uninfected controls (n = 5) at the same time point. Differences between control and infected groups were analysed by ANOVA indicating significantly increased expression of IFN-γ in infected over control birds at 3 and 4 weeks post infection (P < 0.05).