Mikula Ivan, Bhide Mangesh, Pastorekova Silvia, Mikula Ivan
Laboratory of Biomedical Microbiology and Immunology, University of Veterinary Medicine and Pharmacy, Komenskeho-73, Kosice, Slovakia.
Vet Immunol Immunopathol. 2010 Nov 15;138(1-2):51-9. doi: 10.1016/j.vetimm.2010.06.015. Epub 2010 Jun 30.
Toll-like receptors (TLRs) 2, 3, 4, 7, 8 and 9 play a crucial role in the recognition of viral entities and modulation of the innate immune system. This work presents sequence analysis of ovine TLR7 and TLR8 genes, depicts novel mutations and describes frequencies of mutations in Maedi Visna infected and healthy sheep. Totally 48 samples of the breed Tsigai were analyzed for the presence of mutations. Within 20 mutations, 14 were silent whereas 6 were missense. The frequencies of missense mutations in the Maedi Visna infected compared to non-infected sheep were: Lys115Glu (P-0.766, F-test), Asn117 (P-0.380) and Lys818Arg (P-0.739). These three mutations were localized in extra LRR (lucine rich repeat) region of TLR7, while mutation Ile73Leu (P-0.498) was located within LRR2 motif. Both mutations in TLR8, Asn165Lys (P-1.0) and Tyr349His (P-0.700), were present in extra LRR region. The secondary structure analysis of ovine TLR7 and TLR8 revealed conserved LRR motif structure, however with some irregularities compared to cattle and human. Transmembrane domains of TLR7 and TLR8 showed 100% homology between sheep and cattle wherein no mutations were found. In both TLRs TIR domains were highly conserved with occurrence of 4 silent mutations. Mutations in TLR7 and TLR8 may play an important role as predisposition factor for Maedi Visna infection. Considering the sequence homology among sheep, cattle and human genes encoding TLR7 and TLR8, we predict their similar function, localization and downstream signaling.
Toll样受体（TLR）2、3、4、7、8和9在识别病毒实体以及调节先天性免疫系统方面发挥着关键作用。这项工作对绵羊TLR7和TLR8基因进行了序列分析，描绘了新的突变情况，并描述了梅迪 - 维斯纳病感染羊和健康羊的突变频率。总共对48个齐盖品种的样本进行了突变检测分析。在20个突变中，14个是沉默突变，6个是错义突变。与未感染梅迪 - 维斯纳病的绵羊相比，感染羊中错义突变的频率分别为：赖氨酸115谷氨酸（P - 0.766，F检验）、天冬酰胺117（P - 0.380）和赖氨酸818精氨酸（P - 0.739）。这三个突变位于TLR7的额外富含亮氨酸重复序列（LRR）区域，而异亮氨酸73亮氨酸突变（P - 0.498）位于LRR2基序内。TLR8的两个突变，天冬酰胺165赖氨酸（P - 1.0）和酪氨酸349组氨酸（P - 0.700），都存在于额外的LRR区域。绵羊TLR7和TLR8的二级结构分析揭示了保守的LRR基序结构，不过与牛和人的相比存在一些不规则之处。TLR7和TLR8的跨膜结构域在绵羊和牛之间显示出100%的同源性，未发现突变。在两个TLR的TIR结构域中高度保守，出现了4个沉默突变。TLR7和TLR8中的突变可能作为梅迪 - 维斯纳病感染的易感因素发挥重要作用。考虑到编码TLR7和TLR8的绵羊、牛和人类基因之间的序列同源性，我们预测它们具有相似的功能、定位和下游信号传导。
