Transcriptome analysis reveals a complex response to the RGNNV/SJNNV reassortant Nervous Necrosis Virus strain in sea bream larvae

The gilthead sea bream (Sparus aurata) is a marine fish of great importance for Mediterranean aquaculture. This species has long been considered resistant to Nervous Necrosis Virus (NNV), an RNA virus that causes massive mortalities in several farmed animals. However, the recent appearance RGNNV/SJNNV reassortant strains started pose serious threat hatcheries, as it able infect larvae and juveniles this species. While host response NNV extensively studied adult fish, little attention devoted early life history stages, which are generally most sensitive ones. Here we report first time time-course RNA-seq analysis on 21-day old experimentally infected with strain. NNV-infected mock-infected samples were collected at four points (6 h, 12 24 48 h post infection). Four biological replicates, each consisting five pooled larvae, analysed point group. A large set genes found be significantly regulated, especially h), heat shock protein encoding transcripts being up-regulated (e.g. hspa5, dnaj4, hspa9, hsc70), while many immune down-regulated myd88 irf5 T06, pik3r1, stat3, jak1, il12b il6st T12). gene enrichment (GSEA) identified altered pathways/processes. For instance, formation peroxisomes, important anti-viral components well essential nervous system homeostasis, autophagy pathway 6 infection (hpi). Finally, two custom “reactomes” (i.e. significant sets observed other studies) defined used. reactome integrated transcriptomic different species, second one included all stimulated either by interferon (IFN) or IFN Chikungunya zebrafish. Genes both reactomes showed predominant up-regulation 6hpi 12hpi general down-regulation 24hpi. Such evidence suggest certain degree similarity between NNV, IFN- viral-stimulated pathways argues possible interference against response.