Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada.
Cargill Innovation Center-Colaco, Calbuco, Chile.
Front Immunol. 2020 Oct 28;11:567838. doi: 10.3389/fimmu.2020.567838. eCollection 2020.
Bacterial Kidney Disease (BKD), which is caused by a Gram-positive, intracellular bacterial pathogen (), affects salmonids including Atlantic salmon (). However, the transcriptome response of Atlantic salmon to BKD remained unknown before the current study. We used a 44K salmonid microarray platform to characterise the global gene expression response of Atlantic salmon to BKD. Fish (~54 g) were injected with a dose of (H-2 strain, 2 × 10 CFU per fish) or sterile medium (control), and then head kidney samples were collected at 13 days post-infection/injection (dpi). Firstly, infection levels of individuals were determined through quantifying the level by RNA-based TaqMan qPCR assays. Thereafter, based on the qPCR results for infection level, fish ( = 5) that showed no (control), higher (H-BKD), or lower (L-BKD) infection level at 13 dpi were subjected to microarray analyses. We identified 6,766 and 7,729 differentially expressed probes in the H-BKD and L-BKD groups, respectively. There were 357 probes responsive to the infection level (H-BKD vs. L-BKD). Several adaptive and innate immune processes were dysregulated in -infected Atlantic salmon. Adaptive immune pathways associated with lymphocyte differentiation and activation (e.g., lymphocyte chemotaxis, T-cell activation, and immunoglobulin secretion), as well as antigen-presenting cell functions, were shown to be differentially regulated in response to BKD. The infection level-responsive transcripts were related to several mechanisms such as the JAK-STAT signalling pathway, B-cell differentiation and interleukin-1 responses. Sixty-five microarray-identified transcripts were subjected to qPCR validation, and they showed the same fold-change direction as microarray results. The qPCR-validated transcripts studied herein play putative roles in various immune processes including pathogen recognition (e.g., ), antibacterial activity (e.g., and ), regulation of immune responses (e.g., and ), T-/B-cell differentiation (e.g., and ), T-cell functions (e.g., and ), and antigen-presenting cell functions (e.g., ). The present study revealed diverse immune mechanisms dysregulated by in Atlantic salmon, and enhanced the current understanding of Atlantic salmon response to BKD. The identified biomarker genes can be used for future studies on improving the resistance of Atlantic salmon to BKD.
细菌性肾病（BKD）是由一种革兰氏阳性、细胞内细菌病原体（）引起的，影响包括大西洋鲑鱼（）在内的鲑鱼。然而，在当前研究之前，人们对大西洋鲑鱼对 BKD 的转录组反应知之甚少。我们使用了一个 44K 鲑鱼微阵列平台来描述大西洋鲑鱼对 BKD 的全基因表达反应。将大约 54 克的鱼（）用剂量（H-2 株，每鱼 2×10 CFU）或无菌介质（对照）注射，然后在感染/注射后 13 天（dpi）采集头肾样本。首先，通过基于 RNA 的 TaqMan qPCR 检测来定量水平来确定个体的感染水平。此后，根据 13 dpi 时的感染水平的 qPCR 结果，将无（对照）、较高（H-BKD）或较低（L-BKD）感染水平的 5 条鱼（）进行微阵列分析。在 H-BKD 和 L-BKD 组中分别鉴定出 6766 个和 7729 个差异表达探针。有 357 个探针对感染水平（H-BKD 与 L-BKD）有反应。在感染的大西洋鲑鱼中，几种适应性和先天免疫过程被失调。与淋巴细胞分化和激活相关的适应性免疫途径（如淋巴细胞趋化性、T 细胞激活和免疫球蛋白分泌）以及抗原呈递细胞功能，也显示出对 BKD 有差异调节。感染水平反应性转录物与几种机制有关，如 JAK-STAT 信号通路、B 细胞分化和白细胞介素-1 反应。对 65 个微阵列鉴定的转录物进行 qPCR 验证，它们的变化方向与微阵列结果相同。本文研究的 qPCR 验证的转录物在多种免疫过程中发挥作用，包括病原体识别（如）、抗菌活性（如和）、免疫反应调节（如和）、T-/B 细胞分化（如和）、T 细胞功能（如和）和抗原呈递细胞功能（如）。本研究揭示了 感染大西洋鲑鱼时失调的多种免疫机制，增强了对大西洋鲑鱼对 BKD 反应的现有理解。鉴定的生物标志物基因可用于未来提高大西洋鲑鱼对 BKD 抵抗力的研究。
