Transcriptome Analysis of the Immune Process of Golden Pompano (Trachinotus ovatus) Infected with Streptococcus agalactiae

Abstract

The golden pompano (Trachinotus ovatus) is one of the most economically valuable marine fishes in South China. Streptococcus agalactiae, an infectious Gram-positive bacterium that is highly destructive for golden pompano culture, has recently caused massive losses to the golden pompano industry. This study aimed to investigate the dynamic immune response of golden pompano to S. agalactiae infection, using RNA-seq analysis at two different time points after infection. Abundances of differentially expressed genes (DEGs) gradually increased in the liver and spleen 48–120 h post-infection, whereas those in the head kidney were lower at 120 h than at 48 h. Pathway enrichment analysis of DEGs revealed that genes related to the complement system were continuously transcribed between 48 and 120 h. Metabolic and immune-regulation-related pathways were highly enriched in the liver 48 h after infection. Transcriptome analysis was verified using quantitative PCR for eight genes with similar expression trends. This study revealed the inflammatory response of golden pompano after S. agalactiae infection, including inflammation-related chemokines and signaling pathways. Our findings provide a theoretical basis for studying S. agalactiae resistance in golden pompano and provide a reliable resource for the genetic breeding of fish.