Fu Xiaozhe, Li Wenxian, Kong Minghui, Liang Hongru, Lin Qiang, Niu Yinjie, Luo Xia, Ma Baofu, Zhou Jin, Li Ningqiu
Key Laboratory of Fishery Drug Development, Ministry of Agriculture and Rural Affairs, Guangdong Province Key Laboratory of Aquatic Animal Immune and Sustainable Aquaculture, Pearl River Fishery Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China.
Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
Vaccines (Basel). 2025 Jun 16;13(6):645. doi: 10.3390/vaccines13060645.
BACKGROUND/OBJECTIVES: Largemouth bass rhabdovirus ( rhabdovirus, MSRV) disease causes high mortality in largemouth bass farming. Therefore, vaccine development is critical for largemouth bass prevention against MSRV.
An attenuated strain, denoted as MSRV-0509, was selected through intraperitoneal injection and immersion challenge assays, followed by plaque purification. The biological characteristics of MSRV-0509, including optimal inoculation dose, replication kinetics, thermostability, pH resistance, chloroform tolerance, and storage viability, were determined via viral titration. Spatiotemporal distribution patterns in largemouth bass post-intraperitoneal injection or immersion infection were quantified by qPCR. Immunoprotective efficacy was evaluated through intraperitoneal and immersion vaccination. Mechanistic insights were explored via relative qPCR and serum neutralization assays. Safety was assessed by single-dose overdose immunization and virulence reversion experiments.
An attenuated strain MSRV-0509 was screened through a challenge assay, exhibiting complete avirulence in largemouth bass compared to the virulent strain SCRV-T6. MSRV-0509 demonstrated optimal replication at low MOI (0.0001) in CPB cells, with peak titers (10 TCID/mL) at 96 h post-infection. The virus showed susceptibility to high temperatures, lipid solvents and acidic conditions, with prolonged stable storage viability at -80 °C. Tissue distribution revealed the spleen as the primary target after intraperitoneal injection, while immersion restricted infection to gills, with rapid clearance by 3-6 dpi. Vaccination trials identified 5 × 10 TCID/fish via intraperitoneal injection and 10 TCID/mL via immersion as effective immunizing doses, providing 100% relative survival post-challenge. Immune gene expression and serum neutralization showed Th1 and Th2 activation via intraperitoneal injection (elevated IL-12, IFN-γ, IL-10, IgM), whereas only the Th1 response was activated after vaccine immersion. No abnormality and mortality were observed in single overdose vaccination and virulence reversion experiments, confirming that MSRV-0509 was safe.
These results proved that MSRV-0509 could be a promising vaccine candidate to protect largemouth bass from MSRV disease.
背景/目的：大口黑鲈弹状病毒（MSRV）病在大口黑鲈养殖中会导致高死亡率。因此，疫苗研发对于大口黑鲈预防MSRV至关重要。
通过腹腔注射和浸泡攻毒试验筛选出一株减毒株，命名为MSRV-0509，随后进行蚀斑纯化。通过病毒滴定法测定MSRV-0509的生物学特性，包括最佳接种剂量、复制动力学、热稳定性、耐pH值、耐氯仿性和储存活力。通过qPCR定量大口黑鲈腹腔注射或浸泡感染后的时空分布模式。通过腹腔注射和浸泡接种评估免疫保护效果。通过相对qPCR和血清中和试验探索作用机制。通过单剂量过量免疫和毒力回复实验评估安全性。
通过攻毒试验筛选出减毒株MSRV-0509，与强毒株SCRV-T6相比，其在大口黑鲈中表现出完全无毒力。MSRV-0509在CPB细胞中低MOI（0.0001）时显示出最佳复制，感染后96小时达到峰值滴度（10 TCID/mL）。该病毒对高温、脂质溶剂和酸性条件敏感，在-80°C下储存活力延长。组织分布显示腹腔注射后脾脏是主要靶器官，而浸泡感染局限于鳃，在感染后3-6天迅速清除。疫苗接种试验确定腹腔注射5×10 TCID/鱼和浸泡10 TCID/mL为有效免疫剂量，攻毒后相对存活率为100%。免疫基因表达和血清中和显示腹腔注射通过激活Th1和Th2（IL-12、IFN-γ、IL-10、IgM升高），而疫苗浸泡后仅激活Th1反应。在单剂量过量接种和毒力回复实验中未观察到异常和死亡，证实MSRV-0509是安全的。
这些结果证明MSRV-0509可能是一种有前途的疫苗候选物，可保护大口黑鲈免受MSRV病侵害。
