Giovanni Andre, Shi Yin-Ze, Wang Pei-Chi, Tsai Ming-An, Chen Shih-Chu
International Program of Ornamental Fish Technology and Aquatic Animal Health, International College, National Pingtung University of Science and Technology, Pingtung, Taiwan.
Department of Agricultural Biotechnology, College of Agriculture, National Chiayi University, Chiayi, Taiwan.
J Fish Dis. 2025 Nov;48(11):e14154. doi: 10.1111/jfd.14154. Epub 2025 May 26.
Streptococcus iniae is a pathogenic bacterium that causes severe infections and high mortality rates in threadfin fish farms. Recurrent streptococcosis outbreaks underscore the urgent need for effective vaccination strategies. This study investigates an innovative recombinant protein vaccine incorporating a recombinant C5a peptidase encoding 1780 bp from S. iniae to enhance the immune response of the four-finger threadfin fish (Eleutheronema tetradactylum). Vaccine efficacy was assessed by evaluating specific antibody titres, lysozyme activity and the immune-related gene expression in a challenge test. The results demonstrated that fish immunised with C5a, FKC and C5a + FKC showed significantly higher specific antibody titres and lysozyme activity than the control group. Notably, rC5a + FKC displayed the highest IgM levels against the C5a antigen at 28 dpv expression. The rC5a-based vaccine significantly increased TNFα, IL-10 and IL-12 one day after immunisation, correlating with elevated serum antibody levels and the upregulated immune-related genes (C2, CD8). Fish immunised with the rC5a + FKC vaccine exhibited a stronger immune response and greater protective efficacy against the highly virulent S. iniae strain, with a relative survival rate of 97.5%. The combination rC5a + FKC RPS results are higher than those of the single antigens FKC (87.5%) and rC5a (30%), highlighting the potential of the rC5a and FKC vaccine combination as a promising method for preventing and treating S. iniae infections in threadfin fish, supporting healthier fish stocks and sustainable aquaculture practices.
海豚链球菌是一种病原菌，可在金线鱼养殖场引发严重感染并导致高死亡率。链球菌病的反复爆发凸显了制定有效疫苗接种策略的迫切需求。本研究调查了一种创新的重组蛋白疫苗，该疫苗包含编码来自海豚链球菌的1780 bp的重组C5a肽酶，以增强四指金线鱼（Eleutheronema tetradactylum）的免疫反应。通过在攻毒试验中评估特异性抗体滴度、溶菌酶活性和免疫相关基因表达来评估疫苗效力。结果表明，用C5a、FKC和C5a + FKC免疫的鱼比对照组显示出显著更高的特异性抗体滴度和溶菌酶活性。值得注意的是，rC5a + FKC在接种后28天针对C5a抗原显示出最高的IgM水平。基于rC5a的疫苗在免疫后一天显著增加了TNFα、IL-10和IL-12，这与血清抗体水平升高和免疫相关基因（C2、CD8）上调相关。用rC5a + FKC疫苗免疫的鱼对高毒力海豚链球菌菌株表现出更强的免疫反应和更大的保护效力，相对存活率为97.5%。rC5a + FKC的相对保护率结果高于单一抗原FKC（87.5%）和rC5a（30%），突出了rC5a和FKC疫苗组合作为预防和治疗金线鱼海豚链球菌感染的一种有前景方法的潜力，有助于维持更健康的鱼群数量和可持续的水产养殖实践。
