迟缓爱德华氏菌感染斑马鱼的模型构建及病理分析

Construction and pathological analysis of a zebrafish model infected with Edwardsiella tarda

摘要:

【目的】本研究旨在建立迟缓爱德华氏菌感染斑马鱼的模型，以提供疾病模型用于病理学、药理学和药物学研究。【方法】通过不同途径对斑马鱼进行人工感染，模拟自然感染状态，并研究迟缓爱德华氏菌对斑马鱼的致病机理，包括死亡率、行为变化、生化指标和病鱼机体抗氧化能力的变化情况。【结果】比较3种感染途径，显示腹腔注射的致病力最强。迟缓爱德华氏菌感染后，斑马鱼表现出眼球突出、肛门出血、溃疡和腹水等症状。病理检查显示，感染后的斑马鱼发生急性炎症，可见肝细胞广泛坏死脱落，肝小叶萎缩，周围见吞噬细胞聚集。从患病斑马鱼体内分离出TX菌株，并通过特异性引物聚合酶链式反应(polymerase chain reaction, PCR)鉴定为迟缓爱德华氏菌，确定该菌的半致死浓度LD₅₀为3.65×10² 菌落形成单位(colony forming units, CFU)尾。与对照组相比，注射感染组的超氧化物歧化酶(superoxide dismutase, SOD)活力降低22.26%，丙二醛(malondialdehyde, MDA)显著升高16倍，酸性磷酸酶(acid phosphatase, ACP)活性和碱性磷酸酶(alkaline phosphatase, AKP)活性分别上升38.99%和24.36%。【结论】本研究建立了斑马鱼腹腔注射感染迟缓爱德华氏菌的疾病模型，感染后出现典型的疾病症状和生理生化特征，确定了半致死感染剂量，为迟缓爱德华氏菌感染水生动物的病理学研究和防治爱德华氏菌病的药物研制提供科学理论参考。

Abstract:

[Objective] To establish a zebrafish model of Edwardsiella tarda infection for the pathological studies and the development of drugs. [Methods] Zebrafish were artificially infected through different routes to simulate natural infection states, and the pathogenic mechanism of E. tarda in zebrafish was studied based on mortality, behavioral changes, biochemical indicators, and changes in the antioxidant capacity. [Results] Among the three infection routes, intraperitoneal injection showed the strongest pathogenicity. The zebrafish infected with E. tarda presented symptoms such as exophthalmos, anal bleeding, surface ulcers, and ascites. Pathological examination showed that the infected zebrafish developed acute inflammation, with extensive necrosis, degeneration, and shedding of hepatocytes and phagocytes gathering around. The TX strain was isolated from the diseased zebrafish and identified as E. tarda by polymerase chain reaction (PCR) with specific primers. The median lethal dose (LD₅₀) of the strain was determined to be 3.65×10² colony forming units (CFU)/individual. Compared with the control group, the infection model established by injection showed a decrease of 22.26% in superoxide dismutase activity and increases of 16 folds in malondialdehyde content, 38.99% in acid phosphatase activity, and 24.36% in alkaline phosphatase activity. [Conclusion] An E. tarda infection model was established by intraperitoneal injection in zebrafish, which exhibited typical disease symptoms and physiological and biochemical characteristics, and the LD₅₀ was determined. The findings provide a theoretical reference for the pathological studies and the drug development for E. tarda infections in aquatic animals.