Monogenean Gyrodactylus cichlidarum can cause severe mortality of Nile tilapia (Oreochromis niloticus) fry. To date, reports about mucosal immunity of O. niloticus against this parasite have been rare. In order to explore the mucosal immunity of Nile tilapia against G. cichlidarum infection, the expressions of six adaptive immune-related genes and the contents of specific immunoglobulin IgM and IgT in the skin-associated lymphoid tissues (SALT) were dynamically analyzed after primary and secondary infections. The abundances of G. cichlidarum on the hosts after secondary infection were lower than those after primary parasite infection, which implied that hosts could initiate immune protection against G. cichlidarum reinfection to some degree. The transcription levels of TCR-β and CD4 genes in the skin tissue were significantly up-regulated after primary G. cichlidarum infection, while genes pIgR and IgT were only detected with significant up-regulations during secondary infection. With the exception of pIgR, which had remarkably higher expression in the fish with low parasite loads, all other genes studied tended to have higher mRNA level in the fish with higher parasite loads. The specific IgM content in the skin mucus increased significantly on the 2nd day after the primary exposure, higher than the corresponding value during the secondary exposure, and had significantly positive correlation with the parasite loads during the first parasite infection. These results manifested that acquired immune responses in the SALT of Nile tilapia participated in the resistance against G. cichlidarum infection, underscoring the involvement of mucosal immunity in fish against monogenean infection, and suggesting potential prophylactic treatment of gyrodactylid disease of tilapia.

单基因的Gyrodactylus cichlidarum可以导致尼罗罗非鱼（Oreochromis niloticus）鱼苗的严重死亡。迄今为止，关于尼罗罗非鱼对这种寄生虫的粘膜免疫的报道很少。为了探讨尼罗罗非鱼对慈鲷的感染的黏膜免疫性，在皮肤淋巴组织（SALT）中动态分析了六个适应性免疫相关基因的表达以及特异性免疫球蛋白IgM和IgT的含量。继发感染。继发感染后菊苣的寄主的丰度低于原发性寄生虫感染后的寄主的丰度，这表明寄主可以启动针对慈鲷金盏花再感染到一定程度。原发性菊苣后皮肤组织中TCR-β和CD4基因的转录水平显着上调感染，而仅在继发感染期间检测到pIgR和IgT基因有明显的上调。除了pIgR（在低寄生虫负荷的鱼中具有明显较高的表达）外，所有其他研究基因都倾向于在较高寄生虫负荷的鱼中具有较高的mRNA水平。初次接触后第二天，皮肤粘液中的特异性IgM含量显着增加，高于二次接触时的相应值，并且在首次寄生虫感染期间与寄生虫负荷量显着正相关。这些结果表明，尼罗罗非鱼的SALT中获得的免疫应答参与了对慈鲷的抵抗。 感染，强调了鱼对单基因感染的粘膜免疫的参与，并建议对罗非鱼的陀螺类疾病进行预防性治疗。