Immunobiology for Aquaculture Group, Department of Cell Biology and Histology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, 30100 Murcia, Spain.
Oceanographic Center of Murcia, Spanish Institute of Oceanography, Spanish National Research Council (IEO-CSIC), Carretera de la Azohía s/n. Puerto de Mazarrón, 30860 Murcia, Spain.
Int J Mol Sci. 2022 May 3;23(9):5092. doi: 10.3390/ijms23095092.
Historically, gilthead seabream () has been considered a fish species resistant to nervous necrosis virus (NNV) disease. Nevertheless, mortality in seabream hatcheries, associated with typical clinical signs of the viral encephalopathy and retinopathy (VER) disease has been confirmed to be caused by RGNNV/SJNNV reassortants. Because of this, seabream larvae at 37 and 86 days post-hatching (dph) were infected by immersion with RGNNV/SJNNV and SJNNV/RGNNV reassortants under laboratory conditions, and mortality, viral replication and immunity were evaluated. Our results show that gilthead seabream larvae, mainly those at 37 dph, are susceptible to infection with both NNV reassortant genotypes, with the highest impact from the RGNNV/SJNNV reassortant. In addition, viral replication occurs at both ages (37 and 86 dph) but the recovery of infective particles was only confirmed in 37 dph larvae,; this value was also highest with the RGNNV/SJNNV reassortant. Larvae immunity, including the expression of antiviral, inflammatory and cell-mediated cytotoxicity genes, was affected by NNV infection. Levels of the natural killer lysin (Nkl) peptide were increased in SJNNV/RGNNV-infected larvae of 37 dph, though hepcidin was not. Our results demonstrate that the seabream larvae are susceptible to both NNV reassortants, though mainly to RGNNV/SJNNV, in an age-dependent manner.
历史上，真鲷（）被认为是一种对神经坏死病毒（NNV）疾病具有抗性的鱼类。然而，与病毒性脑脊髓炎和视网膜病变（VER）疾病的典型临床症状相关的真鲷孵化场死亡率已被确认为由 RGNNV/SJNNV 重组病毒引起的。因此，在实验室条件下，用 RGNNV/SJNNV 和 SJNNV/RGNNV 重组病毒对 37 日龄和 86 日龄的真鲷幼鱼进行了浸泡感染实验，评估了死亡率、病毒复制和免疫情况。结果表明，真鲷幼鱼（主要是 37 日龄幼鱼）易感染两种 NNV 重组基因型，其中 RGNNV/SJNNV 重组病毒的影响最大。此外，在两个年龄（37 日龄和 86 日龄）都发生了病毒复制，但仅在 37 日龄幼鱼中确认了感染性颗粒的恢复，而 RGNNV/SJNNV 重组病毒的恢复量最高。幼鱼的免疫反应，包括抗病毒、炎症和细胞介导的细胞毒性基因的表达，受到 NNV 感染的影响。在 37 日龄的 SJNNV/RGNNV 感染的幼鱼中，天然杀伤溶菌素（Nkl）肽的水平增加，而肝素则没有。研究结果表明，真鲷幼鱼易感染两种 NNV 重组病毒，但其主要感染 RGNNV/SJNNV，而且具有年龄依赖性。
