Modulation of the immune response of turbot (Scophthalmus maximus) after infection with viral haemorragic septicaemia virus

Turbot (Scophthalmus maximus) is a valuable resource for aquaculture in Galicia (NW Spain). Since it has been observed that viral hemorraghic septicaemia can affect turbot, among other finfish, increase of knowledge in molecular factors affected by the exposure to pathogen could help to develop strategies of VHSV prevention and treatment. In this study, it has been used a custom oligo-microarray by Agilent to identify genes differentially expressed in several turbot families showing different susceptibility to VHSV. Fishes from each family (n=30) were injected with either VHSV (Resistant) or control medium (Naive) and monitored for 30 days, when each group was splitted in two new groups and rechallenged with VHSV (Infected) or control medium (Control). Gene expression at the head kidney was evaluated, showing than an important proportion of the variation of the gene expression profiles is explained by the genetic background (family). After infection, fish showed an up-regulation of the interferon-induced Mx2 gene, the IL-8 gene and the VHSV-induced protein 5 gene compared with control groups. Familes with high mortality after VHSV infection showed lower levels of expression of molecules secreted in the mucus and, by contrast, higher expression of genes involved in viral entrance into target cells. 4 different families of turbot were subjected to challenged with VHSV and splitted after 30 days in 2

大菱鲆（Turbot, *Scophthalmus maximus*）是西班牙西北部加利西亚地区水产养殖的重要经济种质资源。已有研究表明，病毒性出血性败血症（viral hemorrhagic septicaemia, VHS）可感染大菱鲆在内的多种硬骨鱼类，因此解析病原暴露后宿主分子层面的变化机制，有助于开发病毒性出血性败血症病毒（VHSV）的防控与治疗策略。本研究采用安捷伦（Agilent）定制寡核苷酸微阵列（oligo-microarray），旨在筛选在不同VHSV易感性的大菱鲆家系中差异表达的基因。每个家系的30尾实验鱼分别注射VHSV或对照培养基，分为初始攻毒组与空白对照组，并持续监测30天；随后将每组再拆分为两个新亚组，分别再次攻毒VHSV或注射对照培养基。对头肾（head kidney）组织的基因表达水平进行检测后发现，基因表达谱的显著变异可由遗传背景（家系）解释。与对照组相比，攻毒后的实验鱼干扰素诱导Mx2基因、IL-8基因以及VHSV诱导蛋白5基因均呈现上调表达。VHSV感染后死亡率较高的家系，其黏液分泌相关分子的表达水平更低，而参与病毒靶向细胞入侵过程的基因表达水平则相对更高。本研究共选用4个不同的大菱鲆家系开展VHSV攻毒实验，并于30天后将每组划分为2个亚组。