| 摘要: |
| 本研究以腹腔注射无乳链球菌(Streptococcus agalactiae, WC1535菌株)后的尼罗罗非鱼(Oreochromis niloticus，GIFT strain)为研究对象，研究不同水温下无乳链球菌在尼罗罗非鱼体内的动态分布及消除规律。首先，分析25℃、29℃和33℃3个实验组罗非鱼的感染累积死亡率；其次，对3个实验组罗非鱼进行无乳链球菌的体外分离、培养和计数；然后，分析感染后不同实验组罗非鱼脑、肝脏、脾脏和肾脏组织中无乳链球菌的浓度。结果显示，随着水温的升高罗非鱼的累积死亡率也随之升高，25℃、29℃和33℃组的累积死亡率分别为6.67%、25.56%和78.90%。菌落统计结果显示，随着水温的升高，无乳链球菌在罗非鱼体内的增殖速度加快，同时，单位质量组织(脑、肝脏、脾脏和肾脏)中无乳链球菌的最大载菌量也随之升高。本研究还发现，无乳链球菌在罗非鱼脾脏中的浓度最高，在肾脏中的存活时间最长。综上可知，尼罗罗非鱼感染无乳链球菌后，体内各组织中链球菌的增殖、消除速度均与水温密切相关。本研究为研究无乳链球菌的致病机制奠定基础，也为通过合理调控水温及施药等措施防治尼罗罗非鱼链球菌病的暴发提供科学依据。 |
| 关键词: 温度 尼罗罗非鱼 无乳链球菌 动态分布 消除规律 |
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| Dynamic Distribution and Elimination Patterns of Streptococcus agalactiaein Oreochromis niloticus at Different Water Temperatures |
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GUO Fuqiang1,2, ZHANG Defeng1,3, CAO Jianmeng1, LIU Zhigang1, KE Xiaoli1,3, LU Maixin1,3
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1.Key Laboratory of Tropical & Subtropical Fishery Resource Application & Cultivation, Ministry of Agriculture and Rural Affairs, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380;2.National Demonstration Center for Experimental National Demonstration Center for Experimental, Shanghai Ocean University, Shanghai 201306;3.Key Laboratory of Aquatic Animal Immune Technology, Guangdong Province, Guangzhou 510380
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| Abstract: |
| Based on the dynamic distribution and elimination patterns of Streptococcus agalactiae in Oreochromis niloticus at different water temperatures, we provide a foundation for research on S. agalactiae pathogenesis in O. niloticus, as well as a scientific basis for the prevention and control of S. agalactiae infection in O. niloticus by controlling water temperature and the rational use of drugs. We used O. niloticus infected with S. agalactiae (WC1535 strain) by artificial intraperitoneal injection. First, the mortality rates of infected O. niloticus were assessed at 25℃, 29℃, and 33℃. Then, we performed in vitro isolation, cultured and counted S. agalactiae from the infected fish maintained at three temperatures. Next, we assessed the abundance of S. agalactiae in the brain, liver, spleen, and kidney tissues of the infected fish at the three temperatures. The results showed that fish mortality rate increased with increasing water temperature, and the cumulative mortality rate was 6.67%, 25.56%, and 78.90% at 25℃, 29℃ and 33℃, respectively. Furthermore, the maximum abundance of S. agalactiae in unit mass of the brain, liver, spleen, and kidney tissues of O. niloticus increased with increasing water temperature. Thus, at a high temperature, S. agalactiae propagated rapidly in O. niloticus, whereas the residence time was short. In contrast, at a lower temperature, the propagation time decreased, but the residence time increased. Moreover, our results showed that S. agalactiae abundance was the highest in the spleen and survival time was the longest in the kidney. In conclusion, the propagation and elimination speeds of S. agalactiae in tissues of infected O. niloticus were closely related to water temperature. Our results provide important data for further study of S. agalactiae pathogenesis, ensuring effective prevention and control measures. |
| Key words: Temperature Oreochromis niloticus Streptococcus agalactiae Dynamic distribution Elimination patterns |
