Transcriptomic profiles of spotted knifejaw (Oplegnathus punctatus) spleen in response to Megalocytivirus infection

Megalocytivirus (MCV) is emerging as a major viral pathogen in aquaculture and has caused substantial economic losses due to its wide infectious spectrum. As the spotted knifejaw (Oplegnathus punctatus) is one of the most susceptible fish to MCV, the MCV infection in spotted knifejaw caused massive mortality, therefore significantly hampers the farming industry. Despite of the significant economic importance, the immune response of spotted knifejaw during MCV infection is still unclear, which limits the breeding of resistant fish lines and becomes a research priority for aquaculture worldwide. In this study, we challenged spotted knifejaw with a spotted knifejaw MCV strain (SKIV-SD) and performed a transcriptomic analysis using spleen samples from five different time points (days 0, 1, 4, 7, and 10). Fifteen samples (three for each time point) were employed to construct the RNA libraries. A total of over 100 Gb of clean bases was generated, and the clean reads per library ranged from 39.37 M to 60.87 M. A total of 23,365 genes were annotated, and 32,542 new transcripts were identified. Through a comparative transcriptomic analysis of the five groups, the nucleotide binding oligomerization domain-like (NOD-like) receptor signalling pathway, haematopoietic cell lineage, and cytosolic DNA-sensing pathway were closely related to MCV challenge, and the gene expression levels in these pathways were validated by qPCR. Our data provide a genetic resource and shed light on the immune response to MCV infection in spotted knifejaw.