a Indian Veterinary Research Institute, Animal Genetics Division , Izatnagar , Bareilly , India.
Anim Biotechnol. 2014;25(3):188-99. doi: 10.1080/10495398.2013.856797.
Crossbred cattle are more prone to mastitis in comparison to indigenous cattle. Toll-like receptor 4 (TLR4) recognizes pathogen ligands, for example, lipopolysaccharide (LPS) endotoxin from Escherichia coli and mediates signaling to initiate innate and adaptive immune responses. Mutations in TLR4 can compromise the host immune response to certain pathogens, so it may be a potential candidate for marker assisted selection to enhance mastitis resistance in dairy cattle. Hence, in this study role of bovine TLR4 gene in mastitis resistance was investigated by association as well as expression profiling analysis in crossbred cattle. The animals were divided into mastitis affected and unaffected groups on the basis of history of animals and California Mastitis Test (CMT). PCR-SSCP and Sequence analysis revealed three genotypes of coreceptor binding region 1 (CRBR1) fragment of TLR4 gene namely AA, AB, and BB in both groups of cattle. The logistic regression model did not show any significant effect of these genotypes on the occurrence of clinical mastitis. Moreover, in vitro challenge of peripheral blood mononuclear cells (PBMCs) with LPS failed to show any association of the genotypes with TLR4 gene expression. In a nutshell, in the present study enough evidence was not found for association of the SNP variants of CRBR1 fragment of TLR4 gene with mastitis susceptibility in crossbred cattle.
与本土牛相比，杂交牛更容易患乳腺炎。Toll 样受体 4（TLR4）识别病原体配体，例如大肠杆菌的脂多糖（LPS）内毒素，并介导信号转导，启动先天和适应性免疫反应。TLR4 的突变会损害宿主对某些病原体的免疫反应，因此它可能是标记辅助选择的潜在候选者，以提高奶牛的乳腺炎抗性。因此，本研究通过关联分析和杂交牛的表达谱分析，研究了牛 TLR4 基因在乳腺炎抗性中的作用。根据动物的病史和加利福尼亚乳腺炎测试（CMT），将动物分为乳腺炎感染组和未感染组。PCR-SSCP 和序列分析显示，TLR4 基因的共受体结合区 1（CRBR1）片段在两组牛中存在三种基因型，即 AA、AB 和 BB。逻辑回归模型显示这些基因型对临床乳腺炎的发生没有显著影响。此外，用 LPS 体外刺激外周血单核细胞（PBMC）未能显示基因型与 TLR4 基因表达之间存在任何关联。简而言之，在本研究中，没有足够的证据表明 TLR4 基因 CRBR1 片段的 SNP 变异与杂交牛的乳腺炎易感性有关。
