Application of 4 × 44 Oligo Microarray to Transcriptomic Analysis of Immune Response in Rainbow Trout Infected with Aeromonas salmonicida

Abstract

Rainbow trout, one of the most economically important aquaculture fish species worldwide, is affected by the pathogenic bacteria A. salmonicida, which causes furunculosis outbreaks, leading to huge economic losses. In this study, an oligonucleotide microarray was applied to identify transcriptional changes in the skin of rainbow trout individuals in response to a bacterial infection. Overall, 656 and 434 differentially expressed genes (DEGs) were identified at 2 and 6 days after a bacterial challenge (dpi), respectively. A comparison of moribund (2 dpi) and survivor fish (6 dpi) revealed 169 DEGs. Between these were many genes involved in immune response, including lysozymes, pattern recognition receptors (c-type lectins), antimicrobial peptides (cathelicidin and hepcidin), acute-phase proteins (serum amyloids and haptoglobin), complement cascade proteins (c3, c4, c6 and c7), interleukins (il11 and il1b) and chemokines (ccl19 and cxcl8). Alterations of leptin, eicosanoids and prostaglandins have been found, which suggest metabolic remodeling in conjunction with immune response. Further, the regulation of programmed cell death genes (caspase 8, bcl2 apoptosis regulator, nfkb inhibitor alpha and heme oxygenase) and structural proteins (collagens, myosins, keratins and metalloproteinases) was observed. This study provides, for the first time, a gene expression analysis of rainbow trout skin in response to A. salmonicida infection, revealing the complexity of defense strategies in response to furunculosis.