Major histocompatibility complex (MHC) classes I and II molecule expression profiles in the target tissues of chickens infected by H5N6. At 3 days post-infection, target tissues (i.e., brain, lung, spleen, and bursa of Fabricius) of H5N6-infected chickens were harvested for MHC classes I and II molecule mRNA level detection via quantitative real-time polymerase chain reaction. (A) MHC-I, (B) MHC-II. Data are expressed as M ± SD. Differences were analyzed with a paired Student’s t-test and considered statistically significant at ∗p < 0.05, ∗∗p < 0.01 compared to the control. B, Brain; L, Lung; S, Spleen; BF, Bursa of Fabricius.