Dhara Animesh, Saini Mohini, Das Dhanjit K, Swarup Devendra, Sharma Bhaskar, Kumar Satish, Gupta Praveen K
Centre for Wildlife, Indian Veterinary Research Institute, Izatnagar, Bareilly 243122, India.
Immunogenetics. 2007 Jan;59(1):69-76. doi: 10.1007/s00251-006-0174-6. Epub 2006 Nov 21.
Toll-like receptor 3 (TLR3), an antiviral innate immunity receptor recognizes double-stranded RNA, preferably of viral origin and induces type I interferon production, which causes maturation of phagocytes and subsequent release of chemical mediators from phagocytes against some viral infections. The present study has characterized TLR3 complementary DNA (cDNA) in buffalo (Bubalus bubalis) and nilgai (Boselaphus tragocamelus). TLR3 coding sequences of both buffalo and nilgai were amplified from cultured dendritic cell cDNA and cloned in pGEMT-easy vector for characterization by restriction endonucleases and nucleotide sequencing. Sequence analysis reveals that 2,715-bp-long TLR3 open reading frame encoding 904 amino acids in buffalo as well as nilgai is similar to that of cattle. Buffalo TLR3 has 98.6 and 97.9% identity at nucleotide level with nilgai and cattle, respectively. Likewise, buffalo TLR3 amino acids share 96.7% identity with cattle and 97.8% with nilgai. Non-synonymous substitutions exceeding synonymous substitutions indicate evolution of this receptor through positive selection among these three ruminant species. Buffalo and nilgai appear to have diverged from a common ancestor in phylogenetic analysis. Predicted protein structures of buffalo and nilgai TLR3 from deduced amino acid sequences indicate that the buffalo and nilgai TLR3 ectodomain may be more efficient in ligand binding than that of cattle. Furthermore, TLR3 messenger RNA expression in tissues as quantified by real-time PCR was found higher in nilgai than buffalo.
Toll样受体3（TLR3）是一种抗病毒天然免疫受体，可识别双链RNA，最好是病毒来源的双链RNA，并诱导I型干扰素产生，从而导致吞噬细胞成熟，并随后从吞噬细胞释放化学介质以对抗某些病毒感染。本研究对水牛（Bubalus bubalis）和蓝牛羚（Boselaphus tragocamelus）的TLR3互补DNA（cDNA）进行了表征。从培养的树突状细胞cDNA中扩增出水牛和蓝牛羚的TLR3编码序列，并克隆到pGEMT-easy载体中，通过限制性内切酶和核苷酸测序进行表征。序列分析表明，水牛和蓝牛羚中2715 bp长的TLR3开放阅读框编码904个氨基酸，与牛的相似。水牛TLR3在核苷酸水平上与蓝牛羚和牛的同一性分别为98.6%和97.9%。同样，水牛TLR3氨基酸与牛的同一性为96.7%，与蓝牛羚的同一性为97.8%。非同义替换超过同义替换表明该受体在这三种反刍动物物种中通过正选择进化。在系统发育分析中，水牛和蓝牛羚似乎从一个共同祖先分化而来。从推导的氨基酸序列预测的水牛和蓝牛羚TLR3的蛋白质结构表明，水牛和蓝牛羚TLR3胞外域在配体结合方面可能比牛的更有效。此外，通过实时PCR定量分析发现，蓝牛羚组织中TLR3信使RNA的表达高于水牛。
