转录组分析揭示了大口黑鲈 (Micropterus salmoides) 感染 LMBV 后的宿主免疫反应,Fish & Shellfish Immunology

大口黑鲈（Micropterus salmoides ）是我国重要的经济淡水养殖品种之一。然而，病毒性疾病的爆发总是给大口黑鲈养殖业造成巨大的经济损失。大口黑鲈病毒 (LMBV) 是一种双链 DNA (dsDNA) 病毒，属于虹彩病毒科Ranavirus属，导致养殖的大口黑鲈死亡率很高。然而，宿主反应，尤其是 LMBV 感染所涉及的分子事件在很大程度上仍然不确定。在这里，我们建立了一个体内LMBV 感染模型，并使用 RNA 测序 (RNA-seq) 系统地研究了感染大口黑鲈肝脏和脾脏中宿主基因的 mRNA 表达谱。组织病理学分析表明，脾脏内有坏死细胞和形成的坏死灶，大量嗜碱性细胞，肝细胞体积缩小，细胞核固缩, 在被感染的大口黑鲈的肝脏中观察到肝细胞边界消失。转录组学分析表明，肝脏中 5128 个基因（2804 个上调基因和 2324 个下调基因）和脾脏中 7008 个基因（2603 个上调基因和 4405 个下调基因）的转录水平发生了显着改变。Kyoto Encyclopedia of Genes and Genomes (KEGG) 分析表明，肝脏和脾脏中大量共同调节的差异表达基因 (DEGs) 在与细胞死亡和免疫信号相关的通路中富集，例如细胞凋亡、坏死性凋亡、细胞因子-细胞因子受体相互作用和 JAK-STAT 信号。此外，肝脏中受 LMBV 感染特别调节的 DEGs 在与代谢和细胞死亡相关的 KEGG 通路中显着富集，而脾脏中的那些则富含免疫相关途径。此外，几个随机选择的基因的表达变化，如 SOCS1、IL-6、来自 qPCR 的CXCL2 、CASP8、CYC 和 TNF 与转录组数据一致。总而言之，我们的研究结果将为 LMBV在体内诱导的分子反应的基本模式提供新的见解，而且也有助于理解宿主对虹彩病毒病原体的防御机制。

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Largemouth bass (Micropterus salmoides) is one of the important economical freshwater aquaculture species in China. However, the outbreak of viral diseases always caused great economic losses in the largemouth bass aquaculture industry. Largemouth bass virus (LMBV), a double-stranded DNA (dsDNA) virus belonging to genus Ranavirus, family Iridoviridae causes high mortality in cultivated largemouth bass. However, host responses, especially the molecular events involved in LMBV infection still remained largely uncertain. Here, we established an in vivo model of LMBV infection, and systematically investigated the mRNA expression profiles of host genes in liver and spleen from infected largemouth bass using RNA sequencing (RNA-seq). Histopathological analysis indicated that necrotic cells and the formed necrotic focus were present in spleen, while numerous basophilic cells, hepatocytes volume shrinkage, nucleus pyknosis, and the disappeared boundary of hepatocytes were observed in the liver of infected largemouth bass. Transcriptomic analysis showed that transcription levels of 5128 genes (2804 up-regulated genes and 2324 down-regulated) in liver and 7008 genes (2603 up-regulated and 4405 down-regulated) in spleen were altered significantly. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that numerous co-regulated differentially expressed genes (DEGs) in liver and spleen were enriched in the pathways related to cell death and immune signaling, such as apoptosis, necroptosis, cytokine-cytokine receptor interaction and JAK-STAT signaling. Moreover, the DEGs specially regulated by LMBV infection in liver were significantly enriched in the KEGG pathways related to metabolism and cell death, while those in spleen were enriched in the immune related pathways. In addition, the expression changes of several randomly selected genes, such as SOCS1, IL-6, CXCL2, CASP8, CYC and TNF from qPCR were consistent with the transcriptomic data. Taken together, our findings will provide new insights into the fundamental patterns of molecular responses induced by LMBV in vivo, but also contribute greatly to understanding the host defense mechanisms against iridoviral pathogens.