Molecular responses to the influenza A virus in chicken trachea-derived cells

The influenza A virus infects a broad range of species and spreads easily through the respiratory tract. Because of these characteristics, the influenza A virus has caused pandemic disease in humans and livestock. To investigate the early molecular responses after influenza A virus infection in chickens, we infected tracheal epithelial cells derived from 20-day-old chick embryos with influenza A virus (H1N1). The gene expression patterns of the infected tracheal epithelial cells were analyzed via DNA microarray at different time points (0, 6, 12, 24, and 36 hr) after viral infection. Differentially expressed genes were identified at 6, 12, 24, and 36 hours post infection. A total of 1,936, 2,168, 3,670 and 2,894 genes were upregulated (≥2-fold, P<0.05), whereas 884, 592, 1,503 and 1,925 genes were downregulated at the respective time points (≤0.5-fold, P<0.05). When the differentially expressed genes were functionally categorized, immune-related and defense response gene ontology terms were detected in 12, 24, or 36 hours post infection. Interestingly, in the defense response, most of the gallinacin (GAL) genes were rapidly induced within 24 hr post infection. Subsequently, we predicted transcription factor binding sites within promoters of the GAL gene family, and analyzed the gene expression pattern for the common GAL gene regulatory factors to identify the viral infection-induced immune mechanism. Our results might contribute to an understanding of early host responses and regulatory mechanisms for host defense peptide induction against viral infections in chicken.