Animal Health Research Center (CISA-INIA), Valdeolmos, 28130, Madrid, Spain.
Skretting Aquaculture Research Centre, PO Box 48, Stavanger, 4001, Norway.
Fish Shellfish Immunol. 2019 Nov;94:769-779. doi: 10.1016/j.fsi.2019.09.070. Epub 2019 Sep 30.
Although viruses represent a major threat for cultured fish worldwide, the commercialization of vaccines capable of providing effective and long-lasting protection is still lacking for most of these viral diseases. In this situation, the use of supplemented diets could be a suitable strategy to increase the immune status of the fish and reduce the impact of viral pathogens. Among possible immunostimulants that could be included in these functional feeds, some studies have previously shown that certain β-glucans can significantly increase certain immune parameters of fish and reduce the impact of viral diseases. However, the mechanisms through which β-glucans exert their activity have not been fully elucidated yet. In the current study, we have studied the immune response of different tissues to viral haemorrhagic septicaemia virus (VHSV) in rainbow trout fed with a non-supplemented control diet as well as in fish fed a commercial functional aquafeed (Protec™, Skretting) containing β-glucans, vitamin C, vitamin E and zinc. For this, after 30 days of feeding the fish with one of the two diets, they were subsequently infected with VHSV by bath or mock-infected. After 2 or 6 days post-infection, fish were sacrificed and the levels of transcription of different immune genes such as IgM, IgT, IgD, Mx, interferon γ (IFN γ) and perforin studied in different tissues (kidney, gut and gills). Additionally, the levels of natural IgMs in serum were also determined. Our results demonstrate that fish fed the functional diet were capable of mounting an increased IgM, IgT, IgD and Mx transcriptional response to the virus. Additionally, these fish also showed increased levels of natural IgMs in serum. These results reveal a previously undescribed effect of functional diets on fish Ig production and point to Protec™ as an adequate diet to be incorporated in holistic programs aimed at mitigating the effect of viral diseases.
虽然病毒对全球养殖鱼类构成了重大威胁，但对于大多数病毒性疾病，仍缺乏能够提供有效和持久保护的商业化疫苗。在这种情况下，使用补充饲料可能是一种提高鱼类免疫状态并减轻病毒病原体影响的合适策略。在可能包含在这些功能性饲料中的免疫刺激剂中，一些先前的研究表明，某些β-葡聚糖可以显著提高鱼类的某些免疫参数并减轻病毒性疾病的影响。然而，β-葡聚糖发挥其活性的机制尚未完全阐明。在本研究中，我们研究了饲喂未补充对照饲料的虹鳟鱼以及饲喂含有β-葡聚糖、维生素 C、维生素 E 和锌的商业功能性水产饲料（Protec™，Skretting）的虹鳟鱼对病毒性出血性败血症病毒（VHSV）的不同组织的免疫反应。为此，在饲喂其中一种饮食 30 天后，通过浸泡或模拟感染的方式用 VHSV 感染鱼。感染后 2 或 6 天，处死鱼并研究不同组织（肾脏、肠道和鳃）中不同免疫基因（如 IgM、IgT、IgD、Mx、干扰素 γ（IFN γ）和穿孔素）的转录水平。此外，还测定了血清中天然 IgM 的水平。我们的结果表明，饲喂功能性饮食的鱼能够对病毒产生增加的 IgM、IgT、IgD 和 Mx 转录反应。此外，这些鱼的血清中也显示出更高水平的天然 IgM。这些结果揭示了功能性饮食对鱼类 Ig 产生的以前未描述的影响，并指出 Protec™ 是一种合适的饮食，可以纳入旨在减轻病毒性疾病影响的整体计划中。
