Polymorphism Analysis Of MHC-DRB1Genes In Dorper Sheep And Hu Sheep And Hybridition Of Dorper And Hu Sheep

MHC (major histocompatibilty complex), can also called (Ovine Leucocyte Antigen,OLA), is a tightly linked and highly ploymorphism genes cluster on a single chromosome, andis present in almost all vertebrates. The MHC gene family is divided into three subgroups: classⅠ, class II and class III，The translation products of MHC was called MHC antigen or MHCmolecule, primely participatinig in antigen presentation, trigging and regulating immuneresponse. There is a close relationship between MHC and disease resistance/susceptibility,and immune response and performance. So MHC genes which were taken as candidate geneshave become a hot point of the region of molecule immunogenetics.At present, the ploymorphism of Ovine MHC class II gene was focus on the subregion ofDR and DQ locus，and the exon2of DR locus which codes the functional region (peptidebinding region) is high polymorphism. In this present study, the ploymorphism of OLA-DRB1gene exon2was detected by Polymerase Chain Reaction-Restraction Lengh FragmentPolymorphism (PCR-RLFP) methods in Hu sheep, Dorper sheep and hybridization generationof Dorper sheep and Hu sheep (DH-F1). Which provide a basis for new resistance breeding infuture.The specific experiment content and results as following:1. The ploymerphism of MHC-DRB1gene exon2was investeigated in403Hu sheep,283Dorper sheep and125hybridization generation of Dorper sheep.Hu sheep by nestPCR-RLFP aproach. The result showed that the ploymorphism of exon2gene of OLA-DRB1was extensive, five restriction enzymes at site SacⅠ, SacII, Mval, Hin1Ⅰ and HaeⅢ,rescpeticly. yielding15alles,26genotypes.in Hu sheep,14alles,25genotypes in Dorper sheep,while14alles,23genotype.in F1generation of Dorper sheep and Hu sheep.2. Analysis of Hard-weinberg equilibrium the gene of MHC-DRB1exon2by chi-quaretest showed that all of genomic site in these sheep population doesn’t still attainHardy-weinberg equilibrium (P<0.01).3. Comparing the resitant and susceptive genotypes among Hu sheep, Dorper sheep andDH-F1, it was found that genotypes of HaeⅢ ee and Mval bb were almost screened in Husheep.As Hu sheep breeds was a suscptblity to Mycoplasma Pneumonia, it indicated genotypesof HaeⅢee and Mval bb were susceptibility to Mycoplasma Pneumonia (P<0.01), andgenotype of HaeⅢ dd and Mval cc were appeared in Dorper sheep and DH-F1. As Dorpersheep and DH-F1were resistant to this deseases，this pointed out genotype of HaeⅢ dd andMval cc were resistant to Mycoplasma Pneumonia (P<0.01). After analyzing haplotype withthese resistant genotypes of these sheep breeds, the Mycoplasma Pneumonia susceptibilityresistant haplotype MvaI cc-HaeⅢ dd of Dorper sheep and DH-F1sheep was screened out.Other genotypes were not statistically significant.4. Combined with the previos data, Genetic analysis revealed that MHC-DRB1gene exon 2of seven sheep populations had a high polymorphism. And gentic evolution anlysisdepending on gene frequency of MHC-DRB1exon2in these sheep breeds showed that thereare far genetic distance among Hu sheep and Kasak sheep, Chinese merino sheep (Xinjiangjunken type), Duolang sheep and hybridization between Kazakh sheep and Chinese Merinosheep (KM-F1),while, it is further among Hu sheep and Dorper sheep and hybridizationbetween Dorper sheep and Hu sheep (DH-F1) than the previos sheep populations.indicating thata big disprepansy of MHC-DRB1gene among Hu sheep and Dorper sheep and DH-F1.Thisdifference may relate to disease resistance/susceptibility.