| 无乳链球菌感染方式对罗非鱼血常规和抗体消长规律的影响 |
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| 引用本文： | 顾海闻,农源,蒋薇,王冬英,梁万文,陈汉忠,吴文德.无乳链球菌感染方式对罗非鱼血常规和抗体消长规律的影响[J].南方农业学报,2022,53(10):2821-2828. |
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| 作者姓名： | 顾海闻 农源 蒋薇 王冬英 梁万文 陈汉忠 吴文德 |
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| 作者单位： | 1 广西大学动物科学技术学院, 广西南宁 530004;2 贺州市水产畜牧兽医站, 广西贺州 542899;3 广西水产科学研究院, 广西南宁 530021 |
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| 基金项目： | 国家现代农业产业技术体系广西创新团队病害防治功能专家项目（nycytxgxcxtd-08-02） |
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| 摘 要： | 【目的】明确表皮损伤或某种原因造成的炎症是否是罗非鱼无乳链球菌病暴发的重要诱因，为罗非鱼养殖业疫情预警及无乳链球菌疫苗研制提供参考依据。【方法】将180尾体质量约40 g的吉富罗非鱼随机分为健康组、皮肤创伤组和肠炎组，通过浸泡方式感染无乳链球菌（1.5×106 CFU/mL），分别设3个对应的空白对照组（不感染无乳链球菌）。无乳链球菌感染前及感染后24、48、72、96、120、144和168 h等8个时段，分别每组随机挑选15尾罗非鱼采血，将血液涂片后以吉姆萨染色，观察细胞形态并统计外周血白细胞、中性粒细胞、单核细胞和淋巴细胞数量，同时记录罗非鱼死亡数量。每周以ELISA测定1次罗非鱼血清IgM抗体水平，持续10周。【结果】与健康组罗非鱼相比，皮肤创伤组和肠炎组罗非鱼死亡时间提前，存活率显著降低（P<0.05，下同）。3种感染方式的罗非鱼外周血白细胞、中性粒细胞和淋巴细胞数量在感染初期均呈明显的上升趋势，至感染后168 h皮肤创伤组和肠炎组罗非鱼显著高于健康组罗非鱼（P<0.01，下同），说明无乳链球菌感皮肤创伤或患有肠炎的罗非鱼相对于健康鱼能引起更强烈的免疫反应；皮肤创伤组罗非鱼的外周血单核细胞数量在感染后72~168 h均极显著高于健康组罗非鱼，而肠炎组罗非鱼只在感染后24 h极显著高于健康组罗非鱼。相对于健康组和皮肤创伤组罗非鱼，肠炎组罗非鱼血清抗体水平上升时间更早，持续高水平时间更长；健康组和皮肤创伤组的罗非鱼血清特异性抗体出现时间相近，但皮肤创伤组罗非鱼抗体维持高水平的时间更长。【结论】罗非鱼在无乳链球菌感染前后并发机械性或免疫性病理损伤及炎症，会导致感染死亡率升高，即感染无乳链球菌后会加重因转池、运输、寄生虫感染等造成鱼体表皮受损，或饲料霉变等原因造成的肠炎，进而导致罗非鱼死亡率上升。血常规和抗体水平的消长规律能反映罗非鱼无乳链球菌的感染情况，其中，外周血白细胞数量变化可作为判断罗非鱼感染无乳链球菌后病理损伤和免疫应答的参考指标。
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| 关 键 词： | 罗非鱼 无乳链球菌 存活率 白细胞 抗体水平 |
| 收稿时间： | 2021-10-13 |
Effects of infection modes of Streptococcus agalactiae on blood routine and antibody fluctuation of tilapia （Oreochromis niloticus） |
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| GU Hai-wen,NONG Yuan,JIANG Wei,WANG Dong-ying,LIANG Wan-wen,CHEN Han-zhong,WU Wen-de.Effects of infection modes of Streptococcus agalactiae on blood routine and antibody fluctuation of tilapia （Oreochromis niloticus）[J].Journal of Southern Agriculture,2022,53(10):2821-2828. |
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| Authors: | GU Hai-wen NONG Yuan JIANG Wei WANG Dong-ying LIANG Wan-wen CHEN Han-zhong WU Wen-de |
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| Institution: | 1 College of Animal Science and Technology, Guangxi University, Nanning, Guangxi 530004, China;2 Hezhou Aquatic Animal Husbandry and Veterinary Station, Hezhou, Guangxi 542899, China;3 Guangxi Academy of Fishery Science, Nanning, Guangxi 530021, China |
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| Abstract: | 【Objective】To clarify whether skin injury or inflammation caused by some reasons was an important inducement of tilapia Streptococcus agalactiae disease outbreak, and provide reference for tilapia aquaculture epidemic early warning and development of S. agalactiae vaccine.【Method】A total of 180 Gift Oreochromis niloticus with a body weight of about 40 g were randomly dividedt into three groups named heathy group, skin-injury group, and enteritis group.They were infectedS. agalactiae(1.5×106 CFU/mL) by immersion. At the same time, three blank groups(not infected with S. agalactiae) were set up as a control. When at eight periods of time before tilapia infected with S. agalactiae and at 24, 48, 72, 96, 120, 144 and 168 h after infection, fifteen tilapias were randomly chosen in each group for blood sampling. The blood was smeared and stained with Giemsa for observing the cell morphology and counting the number of peripheral blood leukocytes, neutrophils, monocytes and lymphocytes. The number of dead tilapias was recorded at the same time. The samples of serums were subjected to ELISA to determine the IgM antibody titre against S. agalactiae once a week for 10 weeks.【Result】Compared with healthy group, the dead time of skin-injury group and enteritis group was brought forward, and the survival rates were significantly lower. The number of total leukocytes, neutrophils and lymphocytes in the peripheral blood of three infection modes all increased at the initial phase of infection. While the skin-injury group and enteritis group were extremely significantly higher than that in the healthy group (P<0.01, the same below), indicating that tilapia with skin-injury and enteritis after infected by S. agalactiae had stronger immune response than healthy tilapia. The number of monocytes in the skin-injury group after infection was extremely significantly higher than healthy group at 72-168 h, and that of enteritis group was extremely significantly higher than healthy group at 24 h after infection. The serum antibody level of tilapia in enteritis group increased earlier and lasted longer than that in healthy group and skin-injury group. The specific antibody appeared at similar time in healthy group and skin-injury group, but maintained high level for longer in skin-injury group.【Conclusion】Mechanical or immune pathological damage and inflammation in tilapia before and after S. agalactiae infection would lead to increased infection mortality. That is, the infection of S. agalactiae would aggravate the skin damage of tilapia due to transfer, transportation, parasite infection, or enteritis caused by feed mildew, which would lead to an increase in the mortality of tilapia. The variation of tilapia's blood routine and antibody levelscan reflect the infection status of S. agalactiae. Among them, changes in the number of peripheral blood leukocytes can be used as a reference index for pathological damage and immune response of tilapia infected with S. agalactiae. |
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