Single nucleotide polymorphisms in toll-like receptor genes and case-control association studies with bovine tuberculosis

Research (Published online: 09-05-2016)

5. Single nucleotide polymorphisms in toll-like receptor genes and case-control association studies with bovine tuberculosis - Ashish Bhaladhare, Deepak Sharma, Amit Kumar, Arvind Sonwane, Anuj Chauhan, Ranvir Singh, Pushpendra Kumar, Ramji Yadav, Mohd Baqir, Bharat Bhushan and Om Prakash

Veterinary World, 9(5): 458-464

   doi: 10.14202/vetworld.2016.458-464

Abstract

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Aim: Toll-like receptor 2 (TLR2) and TLR4 genes play critical roles in host recognition of Mycobacterium bovis infection and initiation of innate and adaptive immune response. The present study was aimed at exploring the association of seven single nucleotide polymorphisms (SNPs) in TLR2 and TLR4 genes with susceptibility/resistance against bovine tuberculosis (bTB) infection in cattle.

Materials and Methods: A case-control resource population of 35 positive and 45 negative animals was developed after screening with single intradermal tuberculin test for bTB. Resource population was screened for SNPs in TLR2 and TLR4 genes using polymerase chain reaction-restriction fragment length polymorphism. The PROC LOGISTIC procedure of SAS 9.3 was used to find an association of allelic and genotypic frequencies with bTB.

Results: In TLR2 gene, two of SNPs under study (rs55617172 and rs68268253) revealed polymorphism while in the case of TLR4 gene all four SNPs under investigation (rs8193041, rs207836014, rs8193060, and rs8193069) were found to be polymorphic in case-control population. SNP locus rs55617172 in TLR2 gene was found significantly (p<0.01) associated with susceptibility/resistance to TB in cattle.

Conclusion: These findings indicate the presence of SNPs in TLR2 and TLR4 genes in our resource population. Upon validation in independent, large resource population and following biological characterization, SNP rs55617172 can be incorporated in marker panel for selection of animals with greater resistance to bTB.

Keywords: bovine tuberculosis, immune response, resistance, single nucleotide polymorphisms, toll-like receptors.