Association Of Toll-Like Receptor 4 Exon Ⅲ Polymorphisms With Somatic Cell Score In Xinjiang Brown Battle

Toll like receptors (TLRs) recognize pathogen ligands and mediates signaling to initiate innate and adaptive immune responses. In this experiment, Chinese holstei and XinJiang Brown Battle were used as experimental example. The genetic polymorphisms of TLR4 gene exonⅢwere detected by sequencing in the first and by RFLP in the second. The results showed that T/C polymorphic sites did not cause the AA variation in TLR4 E3+1656; C/T polymorphic sites mutation exists in TLR4 E3+2021, which induced that changed Thr into Ile. Statistical results ofχ2 test indicated that two polymorphism sites in the two populations fitted with Hardy–Weinberg equilibrium(P>0.05). The associations were observed between genotypes and SCS by the least square analysis. The results showed that SCS was not significantly affected by different genotypes in TLR4 E3+1656 (P>0.05);both of a significant different effect between genotype AA and AB was found (P<0.05) ,the difference was significant between genotype AA and BB was found (P<0.01) and no significant difference were detected between genotype AB and BB(P>0.05)in TLR4 E3+2021 site. The AA genotype in TLR4 E3+2021 site would be the best genotype to resist mastitis. In short, the allele A might play an important role in mastitis resistance in bovine. To research the effect of different genotypes of TLR4 E3+2021 site on SCS, part of the mRNA of the gene expression where in TLRs signaling pathway downstream were detected by Quantitative Real-Time PCR. The level of NF-κB1,NF-κB2 and IL-1βtranscripts was significantly correlated with genotype of AA and BB in TLR4 E3+2021 (P<0.05),but the level of TNF,TLR4,IL-10,IL-8,MD-2 and Myd88 transcripts was no significantly correlated with genotype of AA and BB in TLR4 E3+2021(P>0.05). These give the implication: The changes of TLR4 E +2021 base cause the change of NF-κB expression, which would lead to the change of IL-1βexpression of mRNA.