Pseudomonas aeruginosa is known to be multidrug-resistant organisms so its infection is challenging. This study aimed to use the sponge-like reduced protocol in preparation of P. aeruginosa ghosts (PAGs) as a vaccine alternative and evaluate its competency in stimulating the immune response in Nile tilapia. Characterization of PAGs was done using the light, fluorescent and transmission electron microscope. 240 fish have been divided into four groups (60 fish each; three groups were injected with a high, medium, or low dose of PAGs, and a control group. Total and differential leukocyte count, phagocytic activity, lysozyme activity, and gene expression of some immune-related genes were done after the first and booster ghost dose injection. All fish groups were challenged intraperitoneally with P. aeruginosa (1 × 10⁷ CFU ml⁻¹); the mean percent mortality was calculated. Significant immunization potency of the large dose of PAGs was prominent. It is associated with a significant increased number of WBCs, heterophile, lymphocytes, and monocytes. Also the phagocytic activity and indexes were significantly increased by the high and moderate dose of PAGs. Additionally, significant upregulation of immune-related gene ( MHC-II) and inflammatory-related gene ( IL8 ) and maintained expression level of TLR7 were recorded . We conclude that chemically prepared P. aeruginosa ghosts maintained both the 3D structure and surface molecules of live bacteria and also are capable of inducing specific immune responses in Nile Tilapia, and reduced mortalities in challenged fish . Our results indicate the advantage of this procedure for production of bacterial ghost, which can be used in wide a range of hosts.

中文翻译：

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铜绿假单胞菌的 特征 及其在尼罗罗非鱼 （Oreochromis niloticus）中的 免疫能力评估

铜绿假单胞菌 是已知的耐多药生物，因此其感染具有挑战性。这项研究旨在使用海绵状还原协议制备 铜绿假单胞菌 鬼（PAG）作为疫苗替代品，并评估了其在尼罗罗非鱼中刺激免疫反应的能力。使用光，荧光和透射电子显微镜对PAG进行表征。将240条鱼分为四组（每组60条；向三组分别注射高，中或低剂量的PAG）和对照组，白细胞总数和差异白细胞计数，吞噬活性，溶菌酶活性和基因表达。在第一次和加强剂量的幽灵注射后，完成了一些与免疫相关的基因研究，所有鱼群都接受了 铜绿假单胞菌 （1×10 ⁷  CFU ml ^-1）; 计算平均死亡率。大剂量的PAG的显着免疫效力十分突出。它与大量增加的白细胞，嗜异性细胞，淋巴细胞和单核细胞有关。高剂量和中等剂量的PAGs的吞噬活性和指数也显着增加。此外，免疫相关基因（的显著上调 MHC-II） 和炎症相关的基因（ IL8 ）和维持表达水平 TLR7 被记录 。 我们得出结论，化学制备的 铜绿假单胞菌 幽灵既保持了活细菌的3D结构和表面分子，又能够在尼罗罗非鱼中诱导特异性免疫反应，并降低了受攻击鱼类的死亡率 。 我们的结果表明该程序可用于生产细菌幽灵，该幽灵可用于多种宿主。