The Correlation Research Between Polymorphism Of Toll-like Receptor4Gene And Respiratory System Disease

There is a acute and chronic respiratory disease in population of sheep,whichleads to productive reduces even death.TLR4and TLR9gene are related toinflammatory,they may be associated with respiratory disease.The Polymorphism andvariation of TLR4and TLR9gene were investigated in order to find the best allelesfor respiratory disease resistance in the further observation by means of phenotypeand genotype,reveal the genetic characteristics of sheep and provide data for futuresearch.Fragments of DNA containing TLR4exon3and TLR9gene were amplifiedusing PCR-SSCP(Single-strand conformational polymorphism) analysis and DNAsequence analysis were employed to detect genetic variation in485sheep (collectedfrom Shangdan,Longxi and Yongchang) including ones with chronic respiratorydisease.The result as follows:(1)In TLR4exon3,five nucleic acid sequence and fivealleles were found in Shandan country,seven nucleic acid sequence and six alleleswere found in Longxi,six nucleic acid sequence and four alleles were found inYongchang.Nineteen nucleotide polymorphisms were found in the analysis of genesequence,which mainly came from point mutation including transition11,accountingfor57.89%of variation sites; six of transversion,accounting for31.58%of variationsites; one insertion and deletion.(2)In TLR9gene,four nucleic acid sequence and fouralleles were both found in Shandan and Yongchang country three nucleic acidsequence and three alleles were found in Longxi.Seven nucleotide polymorphismswere found in the analysis of gene sequence,including four transition sites,accountingfor57.14%of variation sites; three transversion sites,accounting for42.86%ofvariation sites.The high level of sequence polymorphism detected and varied of locidemonstrated Small-tail Han sheep TLR4exon3and TLR9gene have high level ofsequence polymorphism.The population may have strong resistance to geneticresource. The results showed that Small-tail Han sheep in three areas are allpolymorphic in TLR4exon3and TLR9gene,and there are genetic diversitiesbetween regions.Through further comparative analysis of Small-tail Han sheep withrespiratory disease from phenotype and genotype, indicating that AA and AB of TLR4exon3in the Small-tail Han sheep has genetic potential with the resistance torespiratory infections and provide guidances for respiratory diseases of small-tailedHan sheep breeding. TLR9gene is the candidate gene against respiratory disease inSmall-tail Han sheep, the AA allele can be preferred genotype of respiratory diseaseof Small-tail Han sheep.