A transcriptome analysis focusing on inflammation-related genes of grass carp intestines following infection with Aeromonas hydrophila.

Inflammation is a protective response that is implicated in bacterial enteritis and other fish diseases. The inflammatory mechanisms behind Aeromonas hydrophila infections in fish remain poorly understood. In this study, we performed a de novo grass carp transcriptome assembly using Illumina's Solexa sequencing technique. On this basis we carried out a comparative analysis of intestinal transcriptomes from A. hydrophila-challenged and physiological saline solution (PSS/mock) -challenged fish, and 315 genes were up-regulated and 234 were down-regulated in the intestines infected with A. hydrophila. The GO enrichment analysis indicated that the differentially expressed genes were enriched to 12, 4, and 8 GO terms in biological process, molecular function, and cellular component, respectively. A KEGG analysis showed that 549 DEGs were involved in 165 pathways. Moreover, 15 DEGs were selected for quantitative real-time PCR analysis to validate the RNA-seq data. The results confirmed the consistency of the expression levels between RNA-seq and qPCR data. In addition, a time-course analysis of the mRNA expression of 12 inflammatory genes further demonstrated that the intestinal inflammatory responses to A. hydrophila infection simultaneously modulated gene expression variations. The present study provides intestine-specific transcriptome data, allowing us to unravel the mechanisms of intestinal inflammation triggered by bacterial pathogens.