Transcriptome Analysis Indicates Immune Responses against Vibrio harveyi in Chinese Tongue Sole ( Cynoglossus semilaevis ).

Pathogenic infection of fishes is an important constraining factor affecting marine aquaculture. Insufficient understanding of the molecular mechanisms has affected the diagnosis and corresponding treatment. Here, we reported the dynamic changes of gene expression patterns in the Chinese tongue sole kidney at 16 h, 48 h, 72 h and 96 h after Vibrio harveyi infection. In total, 366, 214, 115 and 238 differentially expressed genes were obtained from the 16 h-vs. -C, 48 h-vs. -C, 72 h-vs. -C and 96 h-vs. -C group comparisons, respectively. KEGG enrichment analysis revealed rapid up-regulation of several immune-related pathways, including IL-17, TNF and TLR signaling pathway. More importantly, time-series analyses of transcriptome showed that immune genes were specifically up-regulated in a short period of time and then decreased. The expression levels of chemokines increased after infection and reached a peak at 16 h. Specifically, Jak-STAT signaling pathway played a crucial role in the regulation during Vibrio harveyi infection. In the later stages of infection, genes in the neuroendocrine pathway, such as glucocorticoid-related genes, were activated in the kidney, indicating a close connection between the immune system and neuroendocrine system. Our dynamic transcriptome analyses provided profound insight into the gene expression profile and investigation of immunogenetic mechanisms of Chinese tongue sole.