Abstract This study was performed to assess the ability of Clostridium perfringens types A and D to induce immunological and inflammatory alterations, and mortalities in Nile tilapia (Oreochromis niloticus). Healthy Nile tilapia (n = 90) with an average body weight of 35 ± 0.5 g were randomly divided into three triplicate groups with ten fish in each aquarium. Fish were injected intraperitoneally (IP) with 0.1 mL of 2.4 × 108 CFU/mL of C. perfringens type A in the first group (G1) and type D in the second group (G2). Fish in the third group (G3) were IP injected with sterile saline and served as control. Clinical signs and postmortem lesions of infected fish started appearing on day 1 post-infection (PI), and the cumulative mortality rates were recorded as 50%, 73%, and 0% in G1, G2, and G3 groups, respectively. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities in the G1 and G2 showed a significant gradual decrease, and reached a peak on day 14, compared to the control group, whereas malondialdehyde (MDA) activity was significantly increased at all-time intervals in G1 and G2. TNF-α showed a significant increase only on day 14 in G1 and G2 compared to the control group. Myeloperoxidase activity (MPO) of both G1 and G2 was increased significantly on day 7 and day 14 compared to the control group and other time periods of exposure. Nitric oxide (NO) activity decreased gradually at 24 h and on day 7 and day 14 for G1 and G2, respectively. The inflammatory biomarker IL-1β showed a significant gradual increase, which reached a peak on day 7 for both G1 and G2 in comparison to control. IL-6 reached a peak on day 14 for G1 and on day 7 for G2. Significant down-regulation of IL-10 occurred on days 7 and 14 post challenge. There was a gradual increase in serum proteins in G1 and G2, which attained a peak on day 14, except γ-globulin, which showed a significant decrease in the same trend. The albumin level decreased gradually in G1 and G2, and among the different periods, and reached a peak at 24 h, followed by on day 7 and finally, on day 14. Lysozyme activity and IgM initially showed a significant increase at 24 h in the G1 and G2 groups compared to the control group and other time periods of exposure; later, decreased gradually on day 7 and day 14. There was a significant decline in complement 3 in G1 and G2 on day 14, followed by day 7 and a significant increase at 24 h. This study has shown that C. perfringens types A and D could be important causative agents of disease and mortality in cultured Nile tilapia species.

中文翻译：

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产毒性产气荚膜梭菌 A 型和 D 型对尼罗罗非鱼存活以及先天免疫、炎症和氧化应激反应的影响

摘要 本研究旨在评估产气荚膜梭菌 A 型和 D 型诱导尼罗罗非鱼 (Oreochromis niloticus) 的免疫和炎症改变以及死亡率的能力。将平均体重为 35 ± 0.5 g 的健康尼罗罗非鱼 (n = 90) 随机分为三组，每个水族箱中有 10 条鱼。第一组 (G1) 和第二组 (G2) 中的 A 型产气荚膜梭菌腹腔 (IP) 注射 0.1 mL 的 2.4 × 108 CFU/mL。第三组（G3）中的鱼用无菌生理盐水进行腹腔注射并作为对照。感染鱼的临床症状和死后病变在感染后 (PI) 的第 1 天开始出现，G1、G2 和 G3 组的累积死亡率分别记录为 50%、73% 和 0%。超氧化物歧化酶（SOD），与对照组相比，G1 和 G2 组的过氧化氢酶 (CAT) 和谷胱甘肽过氧化物酶 (GPX) 活性逐渐降低，并在第 14 天达到峰值，而丙二醛 (MDA) 活性在所有时间间隔均显着增加在 G1 和 G2。与对照组相比，TNF-α 仅在 G1 和 G2 的第 14 天显着增加。与对照组和其他暴露时间段相比，G1 和 G2 的髓过氧化物酶活性 (MPO) 在第 7 天和第 14 天显着增加。对于 G1 和 G2，一氧化氮 (NO) 活性分别在 24 小时和第 7 天和第 14 天逐渐降低。炎症生物标志物 IL-1β 显示出显着的逐渐增加，与对照相比，G1 和 G2 在第 7 天达到峰值。IL-6 在 G1 的第 14 天和 G2 的第 7 天达到峰值。IL-10 的显着下调发生在攻击后第 7 天和第 14 天。G1和G2血清蛋白逐渐升高，第14天达到高峰，除γ-球蛋白外，呈显着下降趋势。白蛋白水平在 G1 和 G2 以及不同时期逐渐下降，在 24 h 达到峰值，随后在第 7 天，最后在第 14 天。溶菌酶活性和 IgM 最初在 24 h 出现显着增加。 G1和G2组与对照组和其他暴露时间段的比较；之后，在第 7 天和第 14 天逐渐减少。补体 3 在第 14 天的 G1 和 G2 中显着下降，随后是第 7 天，并在 24 小时显着增加。该研究表明，C.