Pacific cod (Gadus macrocephalus), as one of the most important economic fish, was seriously infected by the nervous necrosis virus (NNV), especially in the larvae stage. PolyI:C is an effective stimulus of the antivirus system, but whether it can work in the larvae stage is still unknown. In this study, the transcriptomic profiles of 10 day-post hatching (dph) cod larvae challenged with polyI:C was analysed using next-generation sequencing technology. After assembly and annotation, a total of 77,562 unigenes were acquired and 780 differentially expressed genes (DEGs) were identified, including 508 upregulated and 272 downregulated genes. The DEGs were involved in diverse pathways including protein processing in endoplasmic reticulum, peroxisome, carbon metabolism, fatty acid metabolism, and PPAR signaling pathway. Gene expression patterns of five immune relevant genes belonging to IFN signal pathway, such as TLR3, IRF3, MDA5, IPS1 and ATG5, were detected using qPCR. The transcript levels of TLR3, IRF3, MAD5 and IPS1 in cod larvae seems very low, but these genes were upregulated significantly 48h post-challenged with polyI:C, while ATG5 was downregulated 12h after polyI:C challenged. The results indicated that IFN system of cod larvae can be induced by polyI:C, thus considering polyI:C as a potential antivirus agent for cod larvae.

中文翻译：

---

PolyI:C 刺激的太平洋鳕鱼幼虫的免疫反应

太平洋鳕鱼 ( Gadus macrocephalus ))，作为最重要的经济鱼类之一，被神经坏死病毒（NNV）严重感染，尤其是在幼虫阶段。PolyI:C是抗病毒系统的有效刺激物，但能否在幼虫阶段发挥作用尚不清楚。在这项研究中，使用下一代测序技术分析了用 polyI:C 攻击的孵化后 10 天 (dph) 鳕鱼幼虫的转录组谱。经过组装和注释后，共获得77562个unigenes，鉴定出780个差异表达基因（DEGs），其中上调基因508个，下调基因272个。DEGs参与多种途径，包括内质网中的蛋白质加工、过氧化物酶体、碳代谢、脂肪酸代谢和PPAR信号通路。使用 qPCR 检测TLR3、IRF3、MDA5、IPS1和ATG5 。鳕鱼幼虫中TLR3、IRF3、MAD5和IPS1的转录水平似乎非常低，但这些基因在 polyI:C 攻击后 48 小时显着上调，而ATG5在 polyI:C 攻击后 12h 下调。结果表明polyI:C可以诱导鳕鱼幼虫的IFN系统，因此认为polyI:C是一种潜在的鳕鱼幼虫抗病毒剂。