多子小瓜虫感染后草鱼TLR信号通路基因的表达动态

对照组无显著差异（P>0.05）;IRAK4和IRAK1在皮肤和脾脏中的表达也主要呈上调趋势，但在脾脏中IRAK4在感染后第1 d和IRAK1在感染后第6 h的表达呈显著下调趋势;IL-1β和TNF-α在绝大多数时间点均显著上调，但IFN的表达基本没有变化。【结论】草鱼TLR信号通路中的部分TLRs基因（TL1、TLR2、TLR4、TLR9、TLR20和TLR21）、接头蛋白基因（MyD88）、信号转导分子（IRAK4和IRAK1）及下游细胞因子（IL-1β和TNF-α）均参与防御多子小瓜虫感染的免疫反应，尤其是在感染早期和中期发挥关键作用。

关键词： 草鱼;多子小瓜虫;Toll样受体（TLR）;信号通路;基因表达

中图分类号： S941.514                            文献标志码： A 文章编号：2095-1191（2019）09-1885-08

Abstract：【Objective】The immune defense function of some genes in toll-like receptor（TLR） signaling pathway of grass carp（Ctenopharyngodon idella） against Ichthyophthirius multifiliis infection was clarified to provide theoretical reference for the effective prevention and control of I. multifiliis infection on fish. 【Method】After I. multifiliis infection on C. idella， the real-time fluorescent quantitative PCR was employed to examine and analyze the dynamics of gene expression profiles in the skin and spleen of the C. idella at different time points， including 6 h， 12 h， 1 d， 2 d， 3 d， 5 d， and 7 d. These tested genes contained several TLRs genes（TLR1， TLR2， TLR4， TLR9， TLR20， and TLR21）， adaptor proteins genes（MyD88 and TRIF）， signal transducing molecules（IRAK4 and IRAK1）， and cytokines（IL-1β， TNF-α， and IFN）. 【Result】Several TLRs， including TLR1， TLR2， TLR9， TLR20， and TLR21， were up-regulated in the skin and spleen at most time points after I. multifiliis infection. The expression of TLR4 was mostly up-regulated in the skin， but down-regulated in the spleen.The expression trends of two adaptor proteins genes（MyD88 and TRIF） were obviously different. MyD88 expression showed significant up-regulation from day 1 to day 3 after I. multifiliis infection（P<0.05， the same below）， whereas the expression levels of TRIF showed no significant changes at most time points compared with control（P>0.05）. The expressions of both IRAK4 and IRAK1 also were up-regulated in the skin and spleenat most time points. However， the expressions of IRAK4 at day 1 and IRAK1 at 6 h in the spleen were significantly down-regulated after infection， respectively. The expressions of IL-1β and TNF-α were significantly up-regulated at most time points after infection， but the expression of IFN remained substantially unchanged. 【Conclusion】The several genes in TLR signaling pathway of C. idella， including some TLRs genes（TLR1， TLR2， TLR4， TLR9， TLR20， and TLR21）， one adaptor protein gene（MyD88）， two signal transducing molecules（IRAK4 and IRAK1）， and two downstream cytokines （IL-1β and TNF-α）， are widely involved and play crucial roles in the immune defense against I. multifiliis infection， especially in the early and middle stages of the infection.