Comparative analysis of spleen transcriptome of immune response in Sebastes schlegeli against Photobacterium damselae subsp. damselae infection

The previous studies have indicated that Photobacterium damselae subsp. damselae (Pdd) was the pathogen of black rockfish (Sebastes schlegeli) with seriously skin ulcer symptom. This study aimed to explore the spleen transcriptome response of S. schlegeli at 24 h (P24 group) and 48 h (P48 group) after Pdd infection and characterize expression profile of immune-related genes. The fish in the control group were injected with equal volume of PBS. Results showed that there were 2,139 (88.42%), 510 (21.08%) and 242 (10%) differentially expressed genes in PBS vs P24, PBS vs P48 and P24 vs P48 respectively. As the time increases, the number of differential genes gradually decreases. GO annotation indicated that the immune-related function category contributed the most in the PBS vs P24 and PBS vs P48 groups, including immune response, immune system process, immune effector process and regulation of immune system process. KEGG enrichment analysis showed that these genes were located on 277, 184 and 164 signalling pathways in the PBS vs P24, PBS vs P48 and P24 vs P48 groups respectively; among them, 30, 26 and 16 pathways were related to immune system, involving 344, 119 and 24 genes. P24 group involved more immune-related signal pathways and genes than P48 group. RT-qPCR validation indicated that the expression patterns of 10 genes at different time points were well agreed with RNA-Seq analysis. This study provided a better understanding of the molecular responses to photobacteriosis in S. schlegeli.

Automated summary

This study investigated the spleen transcriptome response of black rockfish infected with Photobacterium damselae subsp. damselae, revealing the involvement of immune-related genes in the pathogenesis process over time. The expression profiles of immune-related genes were found to correlate with disease progression, with more immune-related signal pathways and genes involved in the early stage of infection. The findings provide valuable insights into the molecular responses of black rockfish to photobacteriosis.