Departments of Aquatic Animal Health and Analysis and Diagnostics, Norwegian Veterinary Institute, Ås, Norway.
Department of Biotechnology, Fisheries and Economy, UiT Arctic University of Norway, Tromsø, Norway.
Front Immunol. 2024 Feb 14;15:1359552. doi: 10.3389/fimmu.2024.1359552. eCollection 2024.
Piscine red blood cells (RBC) are nucleated and have been characterized as mediators of immune responses in addition to their role in gas exchange. Salmonid RBC are major target cells of Piscine orthoreovirus1 (PRV-1), the etiological agent of heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon (). PRV-1 replicates in RBC , but no viral amplification has been possible in available A. salmon cell lines. To compare RBC basal transcripts and transcriptional responses to PRV-1 in the early phase of infection with non-susceptible cells, we exposed A. salmon RBC, Atlantic salmon kidney cells (ASK) and Salmon head kidney cells (SHK-1) to PRV-1 for 24 h. The RNA-seq analysis of RBC supported their previous characterization as pluripotent cells, as they expressed a wide repertoire of genes encoding pattern recognition receptors (PRRs), cytokine receptors, and genes implicated in antiviral activities. The comparison of RBC to ASK and SHK-1 revealed immune cell features exclusively expressed in RBC, such as genes involved in chemotactic activity in response to inflammation. Differential expression analysis of RBC exposed to PRV-1 showed 46 significantly induced genes (≥ 2-fold upregulation) linked to the antiviral response pathway, including RNA-specific PRRs and interferon (IFN) response factors. In SHK-1, PRV induced a more potent or faster antiviral response (213 genes induced). ASK cells showed a differential response pattern (12 genes induced, 18 suppressed) less characterized by the dsRNA-induced antiviral pathway. Despite these differences, the RIG-I-like receptor 3 () in the family of cytosolic dsRNA receptors was significantly induced in all PRV-1 exposed cells. IFN regulatory factor 1 () was significantly induced in RBC only, in contrast to induced in SHK-1. Differences in IRF expression and activity may potentially affect viral propagation.
鱼类红细胞（RBC）有核，除了在气体交换中起作用外，还被认为是免疫反应的介质。鲑鱼红细胞是鱼类正呼肠孤病毒 1（PRV-1）的主要靶细胞，PRV-1 是养殖大西洋鲑鱼（）心肌和骨骼肌炎症（HSMI）的病原体。PRV-1 在 RBC 中复制，但在现有的鲑鱼细胞系中，没有病毒扩增。为了比较 RBC 基础转录本和对 PRV-1 的转录反应在感染早期与非易感细胞，我们将大西洋鲑鱼 RBC、大西洋鲑鱼肾细胞（ASK）和鲑鱼头肾细胞（SHK-1）暴露于 PRV-1 24 小时。RBC 的 RNA-seq 分析支持其先前作为多能细胞的特征，因为它们表达了广泛的编码模式识别受体（PRRs）、细胞因子受体和抗病毒活性相关基因的基因。将 RBC 与 ASK 和 SHK-1 进行比较，揭示了 RBC 中特有的免疫细胞特征，例如参与炎症反应的趋化活性相关基因。暴露于 PRV-1 的 RBC 的差异表达分析显示，有 46 个显著诱导的基因（≥2 倍上调）与抗病毒反应途径相关，包括 RNA 特异性 PRRs 和干扰素（IFN）反应因子。在 SHK-1 中，PRV 诱导更有效的或更快的抗病毒反应（213 个基因诱导）。ASK 细胞表现出较少特征的差异反应模式（12 个基因诱导，18 个基因抑制），由 dsRNA 诱导的抗病毒途径。尽管存在这些差异，但细胞质 dsRNA 受体家族中的 RIG-I 样受体 3（）在所有 PRV-1 暴露的细胞中均显著诱导。干扰素调节因子 1（）仅在 RBC 中显著诱导，而在 SHK-1 中则诱导。IRF 表达和活性的差异可能会影响病毒的传播。
