Fisheries College of Guangdong Ocean University, Shenzhen Institute of Guangdong Ocean University, Guanedong Provincial Key Laboratory of Aquatic Animal Disease Control and Healthy Culture, Guangdong, China.
Veterinary Aquatic Animal Research & Health Care Unit, Department of Clinical Sciences and Public Health, Faculty of Veterinary Science, Mahidol University, Nakhon-pathom, Thailand.
Fish Shellfish Immunol. 2024 Apr;147:109410. doi: 10.1016/j.fsi.2024.109410. Epub 2024 Feb 2.
Nocardia seriolae has been identified as the causative agent of fish nocardiosis, resulting in serious economic losses in aquaculture. With an aim to screen potential candidates for vaccine development against N. seriolae, the in vivo-induced genes of N. seriolae in hybrid snakehead (Channa maculate ♀ × Channa argus ♂) model were profiled via in vivo-induced antigen technology (IVIAT) in the present study, and 6 in vivo-induced genes were identified as follows: IS701 family transposase (is701), membrane protein insertase YidC (yidC), ergothioneine biosynthesis glutamate-cysteine ligase (egtA), molybdopterin respectively-dependent oxidoreductase (mol), phosphoketolase family protein (Ppl), hypothetical protein 6747 (hp6747). Additionally, the yidC was inserted into eukaryotic expression vector pcDNA3.1-myc-his-A to construct a DNA vaccine named as pcDNA-YidC to evaluate immunoprotection in hybrid snakehead after artificial challenge with N. serioale. Results showed that the transcription of yidC was detected in spleen, trunk kidney, muscle and liver in vaccinated fish, suggesting that this antigenic gene can be recombinantly expressed in fish. Meanwhile, indexes of humoral immunity were evaluated in the vaccinated fish through assessing specific-antibody IgM and serum enzyme activities, including lysozyme (LZM), superoxide dismutase (SOD), acid phosphatase (ACP) and alkaline phosphatase (AKP). Quantitative real-time PCR analysis indicated that pcDNA-YidC DNA vaccine could notably enhance the expression of immune-related genes (CD4、CD8α、MHCIIα、TNFα、IL-1β and MHCIα) in 4 tissues (spleen, trunk kidney, muscle and liver) of the vaccinated fish. Finally, an immuno-protection with a relative survival rate of 65.71 % was displayed in vaccinated fish in comparison to the control groups. Taken together, these results indicate that pcDNA-YidC DNA vaccine could boost strong immune responses in hybrid snakehead and show preferably protective efficacy against N. seriolae, indicating that IVIAT is a helpful strategy to screen the highly immunogenic antigens for vaccine development against fish nocardiosis.
海洋分枝杆菌已被确定为鱼类诺卡氏菌病的病原体，给水产养殖业造成了严重的经济损失。本研究采用活体诱导抗原技术（IVIAT）对杂交乌鳢（♀Channa maculate ×♂Channa argus）模型中海洋分枝杆菌的体内诱导基因进行了分析，以期筛选出针对海洋分枝杆菌的潜在候选疫苗。结果共鉴定出 6 个体内诱导基因，分别为：IS701 家族转座酶（is701）、膜蛋白插入酶 YidC（yidC）、谷氨酰胺半胱氨酸连接酶（egtA）、钼依赖氧化还原酶（mol）、磷酸酮醇酶家族蛋白（Ppl）和 6747 号假定蛋白（hp6747）。此外，将 yidC 插入真核表达载体 pcDNA3.1-myc-his-A 中构建 DNA 疫苗，命名为 pcDNA-YidC，用于评估人工攻毒海洋分枝杆菌后杂交乌鳢的免疫保护效果。结果显示，在接种鱼的脾脏、肾脏、肌肉和肝脏中均检测到 yidC 的转录，表明该抗原基因可在鱼类中重组表达。同时，通过检测特异性抗体 IgM 和血清酶活性（溶菌酶（LZM）、超氧化物歧化酶（SOD）、酸性磷酸酶（ACP）和碱性磷酸酶（AKP））评估了接种鱼的体液免疫指标。定量实时 PCR 分析表明，pcDNA-YidC DNA 疫苗可显著增强接种鱼 4 种组织（脾脏、肾脏、肌肉和肝脏）中免疫相关基因（CD4、CD8α、MHCIIα、TNFα、IL-1β和 MHCIα）的表达。最后，与对照组相比，接种鱼的相对存活率为 65.71%，显示出免疫保护作用。综上所述，pcDNA-YidC DNA 疫苗可增强杂交乌鳢的免疫反应，并对海洋分枝杆菌表现出较好的保护效果，表明 IVIAT 是筛选鱼类诺卡氏菌病疫苗高度免疫原性抗原的有效策略。
