Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, 266237, China; Hubei Hongshan Laboratory, Huazhong Agricultural University, Wuhan, 430070, China.
Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China.
Fish Shellfish Immunol. 2023 Nov;142:109179. doi: 10.1016/j.fsi.2023.109179. Epub 2023 Oct 18.
Largemouth bass ranavirus (LMBV) is highly contagious and lethal to largemouth bass, causing significant economic losses to the aquaculture industry. Oral vaccination is generally considered the most ideal strategy for protecting fish from viral infection. In this study, the fusion protein MCP-FlaC, consisting of the main capsid protein (MCP) as the antigen and flagellin C (FlaC) as the adjuvant, was intracellularly expressed in Pichia pastoris. Subsequently, the recombinant P. pastoris was freeze-dried to prepare the oral vaccine P-MCP-FlaC. Transmission electron microscopy and scanning electron microscopy analysis showed that the morphology and structure of the freeze-dried recombinant P. pastoris vaccine remained intact. The experiment fish (n = 100) was divided into five groups (P-MCP-FlaC, P-MCP, P-FlaC, P-pPIC3.5K, control) to evaluate the protective efficacy of the recombinant vaccine. Oral P-MCP-FlaC vaccine effectively up-regulated the serum enzymes activity (total superoxide dismutase, lysozyme, total antioxidant capacity, and complement component 3). The survival rate of P-MCP-FlaC group was significantly higher than that of the other groups. The mRNA expression of crucial immune genes (IL-1β, TNF-α, MHC-II, IFN-γ, Mx, IgM, IgT) was also signally elevated in P-MCP-FlaC group. Vaccine P-MCP-FlaC markedly inhibited the replication of LMBV in the spleen, head kidney, and intestine, while reducing the degree of lesion in the spleen. These results suggest that the oral P-MCP-FlaC vaccine could effectively control LMBV infection, proving an effective strategy for viral diseases prevention in aquaculture.
大口黑鲈弹状病毒（Largemouth bass ranavirus，LMBV）具有高度传染性和致死性，对水产养殖业造成了重大经济损失。口服疫苗接种通常被认为是保护鱼类免受病毒感染的最理想策略。本研究在毕赤酵母中表达了由主要衣壳蛋白（MCP）作为抗原和鞭毛蛋白 C（FlaC）作为佐剂组成的融合蛋白 MCP-FlaC，随后将重组毕赤酵母冻干制成口服疫苗 P-MCP-FlaC。透射电子显微镜和扫描电子显微镜分析表明，冻干的重组毕赤酵母疫苗的形态和结构保持完整。将 100 条实验鱼（n = 100）分为五组（P-MCP-FlaC、P-MCP、P-FlaC、P-pPIC3.5K、对照组），评估重组疫苗的保护效力。口服 P-MCP-FlaC 疫苗可有效上调血清酶活性（总超氧化物歧化酶、溶菌酶、总抗氧化能力和补体成分 3）。P-MCP-FlaC 组的存活率明显高于其他组。P-MCP-FlaC 组关键免疫基因（IL-1β、TNF-α、MHC-II、IFN-γ、Mx、IgM、IgT）的 mRNA 表达也显著升高。疫苗 P-MCP-FlaC 可显著抑制 LMBV 在脾脏、头肾和肠道中的复制，同时减轻脾脏病变程度。这些结果表明，口服 P-MCP-FlaC 疫苗可有效控制 LMBV 感染，为水产养殖病毒性疾病防控提供了有效策略。
