Skin immune response of rainbow trout (Oncorhynchus mykiss) infected with infectious hematopoietic necrosis virus

Rainbow trout (Oncorhynchus mykiss) is one of the economically important cold-water fish cultivated in the world. The outbreak of infectious hematopoietic necrosis (IHN) seriously restricted the development of rainbow trout farming industry and caused huge economic losses. Fish skin is the largest mucosal immune organ, providing the first line of defense against pathogen invasion. However, the immune mechanisms associated with fish skin remain unclear. To systematically identify skin mucosal immune genes induced by infectious hematopoietic necrosis virus (IHNV) infection, trout transcriptome profiles following IHNV challenge were examined. Transcriptome analysis identified 6905 differentially expressed genes (DEGs) and revealed numerous immune-related DEGs involved in cytokine-cytokine receptor interactions, NOD-like receptor signaling, RIG-I-like receptor signaling, Toll-like receptor signaling, JAK-STAT signaling, chemokine signaling, and TNF signaling pathways, and the expression of these DEGs was significantly up-regulated in the T48Skm group, including NOD1, NLRC3, NLRC5, TLR3, TLR7/8, TRIM25, DHX58, IFIH1, IRF3/7, STAT1, TRAF3, MX1, and HSP90A1. Additionally, highly interactive DEGs network involving immune-related terms and pathways was shown using protein-protein interaction network. The expression patterns of 17 genes were further verified by quantitative real-time PCR, which confirmed the reproducibility and reliability of transcriptome sequencing data. These findings expand our understanding of the innate immune system in rainbow trout skin infected with IHNV, and lay a foundation for further studies of the immune molecular mechanism and disease resistance breeding.