College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, 730070, China.
Animal Husbandry and Fishery Technology Promotion Center of Yuzhong, Yuzhong, 730100, China.
Fish Shellfish Immunol. 2019 Nov;94:294-307. doi: 10.1016/j.fsi.2019.09.006. Epub 2019 Sep 3.
Aeromonas salmonicida is a ubiquitous fish pathogen known to cause furunculosis. With the emergence of new subtypes and the expansion of the host range, it has threatened the health of a variety of marine and freshwater fish, particularly the non-salmonids, manifesting differently from the classical furunculosis. Although there have been reports of infection by atypical strains on the crucian carp, the pathogenesis and tissue pathology remain unclear. In this study, transcriptomics and histopathology were used to analyze the immune response and lesions of crucian carp infected with A. salmonicida. Comparative analysis showed 6579 differentially expressed genes (DEGs) (3428 down-regulated and 3151 up-regulated) were identified on day 5 post-infection (5 dpi). Further annotation and analysis revealed that the DEGs were enriched in enzyme regulator activity, response to oxidative stress, iron ion homeostasis and other functions, and mitogen-activated protein kinase (MAPK), nuclear factor-κB (NF-κB), toll-like receptor (TLR), and nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) etc., and immune-related signaling pathways. Meanwhile, the four C-type lysozyme genes found in all DEGs were significantly up-regulated after infection. In addition, there was severe bleeding on the body of the infected fish. Also, the intestine, liver, spleen, and kidney showed varying degrees of inflammatory damage, especially the goblet cell hyperplasia of intestinal mucosa epithelium and degeneration and necrosis of renal tubular epithelium cells. Additionally, with the increase in pathogen concentration, the cumulative mortality increased, the severity of lesions in the hindgut and head-kidney tissues increased. The relative expression levels of four immune-related genes (TNF-α, IL-1β, IL-11, C-lysozyme) were also significantly upregulated, compared with the control (P < 0.05). In conclusion, this study provides a scientific basis for further study on the immune response, pathological diagnosis, and prevention of crucian carp infection caused by atypical A. salmonicida.
嗜水气单胞菌是一种广泛存在的鱼类病原体，已知可引起疖病。随着新亚型的出现和宿主范围的扩大，它已威胁到多种海洋和淡水鱼类的健康，特别是非鲑鱼鱼类，其表现与经典疖病不同。尽管已有关于鲤鱼感染非典型菌株的报道，但发病机制和组织病理学仍不清楚。在本研究中，使用转录组学和组织病理学分析了感染嗜水气单胞菌的鲤鱼的免疫反应和病变。比较分析显示，感染后第 5 天（5 dpi）鉴定出 6579 个差异表达基因（DEGs）（3428 个下调和 3151 个上调）。进一步注释和分析表明，DEGs 富集在酶调节活性、氧化应激反应、铁离子稳态等功能，以及丝裂原激活蛋白激酶（MAPK）、核因子-κB（NF-κB）、Toll 样受体（TLR）和核苷酸结合寡聚化结构域（NOD）样受体（NLR）等免疫相关信号通路。同时，在所有 DEGs 中发现的四种 C 型溶菌酶基因在感染后均显著上调。此外，感染鱼的体表有严重出血。此外，肠、肝、脾和肾均表现出不同程度的炎症损伤，特别是肠黏膜上皮的杯状细胞增生和肾小管上皮细胞的变性和坏死。此外，随着病原体浓度的增加，累积死亡率增加，后肠和头肾组织的病变程度增加。与对照组相比（P<0.05），四种免疫相关基因（TNF-α、IL-1β、IL-11、C 型溶菌酶）的相对表达水平也显著上调。综上所述，本研究为进一步研究鲤鱼感染非典型嗜水气单胞菌的免疫反应、病理诊断和防治提供了科学依据。
