Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain; Departamento de Genética, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain.
Departamento de Biología Celular e Histología, Facultad de Biología, Universidad de Murcia, IMIB-Arrixaca, 30100 Murcia, Spain.
Fish Shellfish Immunol. 2018 Feb;73:220-227. doi: 10.1016/j.fsi.2017.12.027. Epub 2017 Dec 19.
Interferons (IFNs) play a key role in the innate immunity of vertebrates against viral infections by inducing hundreds of IFN-stimulated genes (ISGs), such as isg15. Isg15 is an ubiquitin-like protein, which can conjugate cellular and viral proteins in a process called ISGylation, although it can also act as a cytokine-like protein. Gilthead seabream (Sparus aurata L.) is an important asymptomatic carrier of viral haemorrhagic septicaemia virus (VHSV) and nodavirus, representing a threat to other co-cultivated susceptible species. In order to better understand virus-host interactions in this fish species, this study addresses the identification and molecular characterization of seabream isg15 (sb-isg15). In addition, the modulation of transcript levels of sb-isg15 was analysed in SAF-1 cells and seabream acidophilic granulocytes (AGs) stimulated in vitro with different pathogen-associated molecular patterns (PAMPs) or inoculated with VHSV and striped jack nervous necrosis virus (SJNNV). The full-length cDNA of sb-isg15 gene, encoding a predicted protein of 155 amino acids, was identified and seen to share the same characteristics as other fish and mammalian isg15 genes. Here we report the clear induction of sb-isg15 transcript levels in SAF-1 cells and AGs stimulated with toll-like receptor (TLR) ligands, such as polyinosinic:polycytidylic acid (poly I:C) or genomic DNA from Vibrio anguillarum (VaDNA), respectively. Furthermore, VHSV and SJNNV inoculation induced a significant degree of sb-isg15 transcription in SAF-1 cells and AGs. However, the relative levels of viral RNA transcription showed that SJNNV replication seems to be more efficient than VHSV in both in vitro systems. Interestingly, sb-isg15 transcript induction elicited by VaDNA was reduced in VHSV- and SJNNV-inoculated AGs, suggesting an interference prompted by the viruses against the type I IFN system. Taken together, these findings support the use of seabream AGs as a valuable experimental system to study virus-host interactions, in which sb-isg15 seems to play an important role.
干扰素 (IFNs) 通过诱导数百种干扰素刺激基因 (ISGs)，如 isg15，在脊椎动物对病毒感染的固有免疫中发挥关键作用。Isg15 是一种泛素样蛋白，可在称为 ISGylation 的过程中将细胞和病毒蛋白连接起来，但它也可以作为细胞因子样蛋白发挥作用。金头鲷 (Sparus aurata L.) 是病毒性出血性败血症病毒 (VHSV) 和诺达病毒的重要无症状携带者，对其他共培养的易感物种构成威胁。为了更好地了解这种鱼类中的病毒-宿主相互作用，本研究对金头鲷 isg15 (sb-isg15) 的鉴定和分子特征进行了研究。此外，还分析了 sb-isg15 在 SAF-1 细胞中的转录水平的变化以及体外用不同的病原体相关分子模式 (PAMPs) 刺激或接种 VHSV 和斜带石斑鱼神经坏死病毒 (SJNNV) 后金头鲷酸性粒细胞 (AGs) 中 sb-isg15 的转录水平。鉴定了 sb-isg15 基因的全长 cDNA，该基因编码一个预测的 155 个氨基酸的蛋白质，并且与其他鱼类和哺乳动物 isg15 基因具有相同的特征。在这里，我们报告了 sb-isg15 转录水平在 SAF-1 细胞和 AGs 中被 Toll 样受体 (TLR) 配体诱导的明显诱导，例如聚肌苷酸：聚胞苷酸 (poly I:C) 或鳗弧菌基因组 DNA (VaDNA)。此外，VHSV 和 SJNNV 接种在 SAF-1 细胞和 AGs 中诱导了 sb-isg15 的显著转录。然而，病毒 RNA 转录的相对水平表明，SJNNV 复制在这两个体外系统中似乎比 VHSV 更有效。有趣的是，在接种 VHSV 和 SJNNV 的 AGs 中，VaDNA 诱导的 sb-isg15 转录减少，表明病毒对 I 型干扰素系统产生了干扰。综上所述，这些发现支持使用金头鲷 AGs 作为研究病毒-宿主相互作用的有价值的实验系统，其中 sb-isg15 似乎发挥了重要作用。
