■诺卡氏菌对各种鱼类产生不利影响,表现出显著的致病特征,严重阻碍了水产养殖的发展。鱼中的N.seriolae感染有很长的潜伏期,早期临床症状不明显。目前没有可行和生态友好的方法来对抗这种疾病的传播。据报道,N.seriolae主要针对感染鱼后组织中的巨噬细胞,并且可以大量增殖,导致鱼的死亡。干扰素-γ(IFN-γ)是调节巨噬细胞活化的关键分子,但对其在N.seriolae预防中的作用知之甚少。
■IFN-γ首先被定义为大嘴鲈鱼(Micropterussalmoides,MsIFN-γ),通过同源性分析,其具有高度保守的IFN-γ特征序列。重组蛋白(rMsIFN-γ)在大肠杆菌中获得(E。大肠杆菌)菌株BL21(DE3)。使用单核细胞/巨噬细胞在体外评估rMsIFN-γ的炎症反应诱导能力。同时,通过N.seriolae感染大口鲈鱼模型评估MsIFN-γ的体内保护作用。
■在由rMsIFN-γ激活的单核细胞/巨噬细胞的炎症反应中,各种细胞因子显著增加。有趣的是,白细胞介素1β(IL-1β)和肿瘤坏死因子α(TNF-a)增加了183和12倍,分别,rMsIFN-γ刺激后。与对照相比,rMsIFN-γ使存活率提高42.1%。肝脏中的细菌负荷,脾脏和头肾明显减少。rMsIFN-γ也显示出更好地诱导IL-1β表达增加,TNF-α,铁调素-1(Hep-1),主要组织相容性复合体I(MHCI),和头肾的MHCII,脾脏和肝脏。组织病理学检查表明,在感染期间,肉芽肿状态从早期坏死灶转变为纤维化。出乎意料的是,rMsIFN-γ组成功减缓了肉芽肿的发展。
■这项工作为进一步研究大口鲈鱼的IFN-γ铺平了道路,并确定了预防N.seriolae的潜在治疗靶标。
Nocardia seriolae adversely impacts a diverse range of fish species, exhibiting significant pathogenic characteristics that substantially impede the progress of aquaculture. N. seriolae infects in fish has a long incubation period, and clinical symptoms are not obvious in the early stages. There is presently no viable and eco-friendly approach to combat the spread of the disease. According to reports, N. seriolae primarily targets macrophages in tissues after infecting fish and can proliferate massively, leading to the death of fish. Interferon-gamma (IFN-γ) is a crucial molecule that regulates macrophage activation, but little is known about its role in the N. seriolae prevention.
IFN-γ was first defined as largemouth bass (Micropterus salmoides, MsIFN-γ), which has a highly conserved IFN-γ characteristic sequence through homology analysis. The recombinant proteins (rMsIFN-γ) were obtained in Escherichia coli (E. coli) strain BL21 (DE3). The inflammatory response-inducing ability of rMsIFN-γ was assessed in vitro using monocytes/macrophages. Meanwhile, the protective effect of MsIFN-γ in vivo was evaluated by N. seriolae infection largemouth bass model.
In the inflammatory response of the monocytes/macrophages activated by rMsIFN-γ, various cytokines were significantly increased. Interestingly, interleukin 1β (IL-1β) and tumor necrosis factor alpha (TNF-a) increased by 183- and 12-fold, respectively, after rMsIFN-γ stimulation. rMsIFN-γ improved survival by 42.1% compared with the control. The bacterial load in the liver, spleen and head kidney significantly decreased. rMsIFN-γ was also shown to better induce increased expression of IL-1β, TNF-α, hepcidin-1(Hep-1), major histocompatibility complex I (MHCI), and MHC II in head kidney, spleen and liver. The histopathological examination demonstrated the transformation of granuloma status from an early necrotic foci to fibrosis in the infection period. Unexpectedly, the development of granulomas was successfully slowed in the rMsIFN-γ group.
This work paves the way for further research into IFN-γ of largemouth bass and identifies a potential therapeutic target for the prevention of N. seriolae.