This study aimed to evaluate the immune response in tilapia (Oreochromis niloticus) in optimum salinity for a vaccination with hyperosmotic infiltration in controlling streptococcosis caused by Streptococcus agalactiae. A total of 100 fish weighing 4.26 ± 1.37 g were immersed in water with a salinity of 0, 10, 20, and 30 g L⁻¹ for 5 min, and then immersed in 10⁹ cfu L⁻¹ S. agalactiae vaccine for 30 min. The challenge test was carried out on 31 days post-vaccination with pathogenic S. agalactiae. Relative percent survival, blood profile, antibody titer, lysozyme activity, and fish blood glucose were measured on day 0, 15, and 30 post-vaccination and 10 post-challenge tests. The results showed that hyperosmotic infiltration with 20 g L⁻¹ resulted in a higher relative percent survival of 88.24% compared to other treatments. Immunological parameters such as total erythrocytes, total leukocytes, hemoglobin levels, hematocrit levels, phagocytic activity, lysozyme as the non-specific immune system, and antibody levels as a specific immune system in fish immersed at 20 g L⁻¹ before vaccination were higher than others. In conclusion, fish immersed in 20 g L⁻¹ before immersion vaccination enhanced non-specific and specific immune defense and increased fish protection against pathogenic S. agalactiae.

本研究旨在评估罗非鱼（尼罗罗非鱼）在最佳盐度下的免疫反应，并进行高渗疫苗接种，以控制无乳链球菌引起的链球菌病。将总共​​100条重4.26±1.37 g的鱼浸入盐度分别为0、10、20和30 g L ^-1的水中5分钟，然后浸入10 ⁹  cfu L ^-1 无乳链球菌疫苗中浸泡30分钟。分钟 免疫试验是在病原性无乳链球菌疫苗接种后第31天进行的。在疫苗接种后第0、15和30天以及挑战后10次测试中，测量了相对存活率，血液概况，抗体滴度，溶菌酶活性和鱼血葡萄糖。结果显示，与其他治疗方法相比，用20 g L ^-1进行的高渗渗透导致相对较高的存活百分率88.24％。免疫前浸入20 g L ^-1的鱼类的总红细胞，总白细胞，血红蛋白水平，血细胞比容水平，吞噬活性，溶菌酶（作为非特异性免疫系统）和抗体水平（作为特异性免疫系统）等免疫学参数高于其他。最后，将鱼浸入20 g L ^-1浸泡疫苗接种之前，增强了非特异性和特异性免疫防御能力，并增强了鱼对病原性无乳链球菌的保护。