猪TLR3 mRNA的表达特征与调控分析及其与感染蓝耳病的关系

Expression and relationship of TLR3 mRNA with PRRS infection and regulatory analysis on its transcription in pigs

克隆了猪Toll样受体3(toll-like receptor 3,TLR3)的部分编码区,分析了其在物种间的同源性;检测了不同组织及感染猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndrome virus,PRRSV)前后不同品种猪肺组织TLR3基因mRNA水平的表达变化,分析了猪TLR3基因5′调控区对转录的影响。结果显示:猪与牛、绵羊等哺乳动物TLR3的同源性较高,与鸡、斑马鱼的同源性较低;TLR3mRNA在猪肝脏、肾脏和小肠组织中的表达较高,而在心脏、子宫、淋巴结、大脑、肌肉、大肠和肺组织中的表达较低,在小脑和扁桃体中几乎检测不到其表达;TLR3基因在抗蓝耳病的大蒲莲猪和对蓝耳病易感的杜大长杂交猪肺组织中的表达存在显著差异,大蒲莲猪中的表达量均显著高于杜大长杂交猪(未攻毒,P<0.05;攻毒,P<0.01);攻毒大蒲莲猪肺组织TLR3mRNA表达量升高,杜大长杂交猪的表达量下降;荧光素酶分析表明,5′调控区-2 952bp至-2 603bp、-1 632bp至-1 079bp区段有增强TLR3表达的顺式元件。结果表明:TLR3的高表达可能与猪对蓝耳病的抗性有关。

In this study,apartial coding region of porcine TLR3 gene and its homology with other species was obtained and analyzed.The expression patterns of TLR3 mRNA in different tissues and in the lung tissues of Dapulian（DPL）and Duroc×Yorkshire×Landrace（DYL）pigs after infection with PRRSV were investigated.The impact of 5′-regulatory region of TLR3 gene on transcription was examined.A higher homology of porcine TLR3 with other mammals,such as bovine and sheep,while a lower homology with chicken and zebra fish were revealed.The expression of porcine TLR3 mRNA is high in liver,spleen and small intestine tissues,compared with that in heart,uterus,lymph nodes,brain,muscle,colon,large intestine and lung tissues,however,was almost undetectable in cerebellum and tonsil.There was a significant difference in expression of TLR3 mRNA between DPL pigs resistant to PRRS and,DYL pigs susceptible to PRRS.The expression of TLR3 in DPL pigs was significantly higher than that of DYL pigs（uninfected pigs：P〈0.05;infected pigs：P〈0.01）.Luciferase assay showed that two regions of-2 952 bp to-2 603 bp and-1 632 bp to-1 079 bp harbor positive cis-regulatory elements.In a conclusion,these data suggest that the high expression of TLR3 was likely related to pigs resistance to PRRS.