两个奥利亚罗非鱼品系对无乳链球菌的耐受性研究

THE TOLERANCE OF TWO BLUE TILAPIA (OREOCHROMIS AUREAUS) SPECIES TO STREPTOCOCCUS AGALACTIAE

  • 摘要: 为探讨两个奥利亚罗非鱼(Oreochromis aureus)品系对无乳链球菌(Streptococcus agalactiae)的耐受性, 研究以奥利亚罗非鱼埃及品系(AE品系)和“夏奥1号”(AX品系)为研究对象, 人工腹腔注射无乳链球菌, 并在感染后0、7h、24h、48h、72h、120h和168h采集罗非鱼血液和脾脏, 比较感染后7d存活率差异, 研究血清生化指标和脾脏促炎性细胞因子表达变化。结果显示, 人工感染后AE奥利亚罗非鱼存活率显著高于AX奥利亚罗非鱼。感染后两种奥利亚罗非鱼血清中的谷丙转氨酶(ALT)、谷草转氨酶(AST)、球蛋白(GLO)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)、乳酸脱氢酶(LDH)和溶菌酶(LZM)含量在感染后都显著升高; 甘油三酯(TG)和白蛋白/球蛋白(A/G)显著下降, 呼吸暴发受抑制; 且AE品系的血清GLO和SOD水平在感染后期显著高于AX品系。定量PCR结果显示两种奥利亚罗非鱼脾脏TNF-αIL-1βIL-6表达在感染后7h都显著升高, 但AE品系在感染后期3种促炎性细胞因子的表达都显著低于AX品系。研究表明, AE品系对无乳链球菌的抗病力强于AX品系, 在感染后期的抗氧化能力更强, 炎症程度更轻, 从而保持对无乳链球菌更大的耐受性。研究结果为培育抗链球菌病的奥尼罗非鱼提供抗性的亲本种质资源。

     

    Abstract: China is the leading producer of tilapia in the world, with a production volume of 1.65 million tons in 2020. However, the tilapia industry in China is facing limitations due to streptococcosis caused by Streptococcus agalactiae, which has become one of the major factors with the increased culture density and the deterioration of culture environment. Breeding new varieties of tilapia resistant to streptococcosis is an important way to mitigate the disease. Different tilapia strains exhibit varying levels of disease resistance. Therefore, this study aimed to explore the tolerance of two blue tilapia species to S. agalactiae, Oreochromis aureus “Xia’ao No. 1” (AX strain) and Egypt strain (AE strain). The survival rate was recorded at different time points. Blood and spleen samples were collected at 0, 7h, 24h, 48h, 72h, 120h and 168h after infection, respectively. The serum biochemical indexes and expression of pro-inflammatory cytokines in spleen of two blue tilapia species were measured. The survival rate of AE strain (30%) was significantly higher than that of the AX strain (10%) at 7d post infection. The alanine aminotransferase (ALT), aspartate aminotransferase (AST), globulin (GLO), alkaline phosphatase (AKP), superoxide dismutase (SOD), lactate dehydrogenase (LDH) and lysozyme (LZM) in the serum of two blue tilapia species increased significantly after infection, whereas triglyceride (TG), albumin/globulin (A/G) decreased significantly. The infection resulted in a strong inhibition of the respiratory burst. The AE strain demonstrated significantly higher serum globulin and SOD levels compared to the AX strain at later stages of infection. The mRNA levels of pro-inflammatory cytokines in the spleen of two blue tilapia species were significantly up-regulated at 7h post infection. Moreover, the gene expression of TNF-α, IL-1β and IL-6 in spleen of AE strain was significantly lower than that observed in AX strain during the later stage of observed period. The study shows that the AE strain exhibits stronger resistance to S. agalactiae compared to the AX strain. The higher antioxidant capacity and less severe inflammation observed at later stages of infection contribute to the increased tolerance of AE strain to S. agalactiae. The results provide valuable parental resistance germplasm resources for breeding streptococcosis resistant hybrid tilapia.

     

/

返回文章
返回