My Ph.D project is to use RNAseq technology to study how the primary lymphoid tissues' transcriptome respond to avian pathogenic Escherichia coli (APEC) in commercial broilers. Through differentially expressed genes detection between different phenotype birds, many potential biomarker genes and vital pathways were identified. Moreover, alternative splicing analysis of those important genes were conducted to understand the molecular basis of host resistance to APEC infection at the earliest stage. These findings would be valuable for understanding animal genetics disease resistance.