斑点叉尾TLR5和TLR5S基因在不同病原诱导下的表达特征

分别用迟钝爱德华氏菌Edwardsiella tarda、嗜水气单胞菌Aeromonas hydrophila、链球菌Streptococcus iniae和斑点叉尾(鱼回)呼肠孤病毒(channel catfish hemorrhage reovirus,CCRV)对斑点叉尾(鱼回)Ictalurus punctatus进行感染实验,取感染后0h、12h、24h、48h、72h和7d的头肾、肠、肝脏和脾脏,采用实时定量PCR方法检测了TLR5和TLR5S基因在这4种免疫相关组织中的时空表达特征,探讨它们与斑点叉尾(鱼回)先天免疫反应的关系.结果表明,链球菌和迟钝爱德华氏菌能够引起TLR5和TLR5S强烈的上调表达,其中以感染链球菌12h后TLR5S在头肾中的表达上调量最为显著,与对照组相比提高了132倍(P＜0.01).在感染嗜水气单胞菌后的24h内TLR5和TLR5S基因的表达量上升,但随后却显示出了明显的下调趋势,而斑点叉尾(鱼回)呼肠孤病毒在TLR5和TLR5S基因表达中起到了明显的抑制作用,于大部分组织中表达下调.在感染12h的脾脏中,TLR5基因的表达量仅为对照组的0.017倍(P＜0.01),而TLR5S基因表达量达到最低,仅为对照组的0.01倍(P＜0.01).从不同的组织来看,TLR5在肠中的表达上调幅度最大,而TLR5S在头肾中的表达增幅最明显,如感染链球菌和迟钝爱德华氏菌12h后,TLR5在肠中的表达量分别增加了50.4倍(P＜0.01)和14.8倍(P＜0.01),TLR5S在头肾中的表达量分别上升了52.8倍(P＜0.01)和132倍(P＜0.01).以上结果进一步证明了TLR5和TLR5S基因在斑点叉尾(鱼回)先天免疫反应过程中发挥着非常重要的作用,同时在抗病原侵袭过程中表现出了一定的组织特异性和病原特异性.

Gene expression of TLR5 and TLR5S in channel catfish Ictalurus punctatus induced by different pathogens

Expression of channel catfish TLR5 and TLR5S genes in the head kidney, intestine, liver and spleen were analyzed by quantitative real time PCR method at 0 h, 12 h, 24 h, 48 h, 72 h and 7 d after infection with Edwardsiella tarda, Aeromonas hydrophila, Streptococcus iniae and channel catfish hemorrhage reovirus (CCRV), respectively. The results showed that TLR5 and TLR5S mRNAs were largely up-regulated by E. tarda and S. iniae and the most significant increase of TLR5S gene expression occurred in head kidney 12h after being challenged with S. iniae, which was 132-fold higher than the PBS control. After infection with A. hydrophila, TLR5 and TLR5S showed up regulation at 12h and 24h and obvious down-regulation at 48h to 7d post-infection. TLR5 and TLR5S genes expression were suppressed by infection with CCRV in most tissues. In spleen, the expression of TLR5 was 0.017-fold while TLR5S was only 0.01-fold compared with PBS control. Among the four immune-related different tissues, the expression of TLR5 and TLR5S showed significant up-regulation in intestine and head kidney. For example, after being challenged with E. tarda and S. iniae, at time point of 12h, the expression of TLR5 increased 50.4-fold and 14.8-fold respectively in intestine, and the expression of TLR5S increased 52.8-fold and 132-fold respectively in head kidney. All data suggested that TLR5 and TLR5S were involved in the immune response of channel catfish against the intracellular bacterial and virus pathogen in a tissue-specific and pathogen-specific manner, and further confirmed that both of them played significant roles in the channel catfish innate immunity.