Avian infectious bronchitis virus disrupts the melanoma differentiation associated gene 5 (MDA5) signaling pathway by cleavage of the adaptor protein MAVS

Yu, Liping; Zhang, Xiaorong; Wu, Tianqi; Su, Jin; Wang, Yuyang; Wang, Yuexin; Ruan, Baoyang; Niu, Xiaosai; Wu, Yantao

IBV could replicate sufficiently in 9-11 day old chicken embryos, to evaluate the relationship between antiviral response and viral replication in different embryo tissues, chicken embryos were inoculated with IBV, then the trachea, intestine, kidney, lung, liver, and muscle of the embryos were collected 72 h post-infection. The replication ability of IBV was determined by absolute quantification real-time PCR. IBV can be detected in all tissues, and the viral genome load was higher in the lung and trachea compared with other tissues (Fig. 3a) . Eight housekeeping genes were selected for screening stably expressed reference genes in different chicken embryo tissues to be used in comparison to the determined cytokine expression studies (Additional file 2: Figure S1 ). The transcription of the antiviral cytokines chMDA5, chIFN-β, chIFN-λ and chMx in different tissues was normalized using three different reference genes (Additional file 2: Figure S1 ). We found that variability in expression for each gene was similar when normalized to different stable reference genes (Additional file 3: Figure S2 ). Therefore, β-actin was selected as an internal reference gene in this study. The data showed that chMDA5 (Fig. 3b) was expressed in all tissues, and stronger expression was observed in the intestine and lung (P ≤ 0.01) and kidney (P ≤ 0.05). IBV induced higher chIFN-β (Fig. 3c) , chIFN-λ (Fig. 3d) and chMx (Fig. 3e ) transcription in the lung; chMx and chIFN-λ transcription in kidneys than the negative control group (P ≤ 0.01).