Polymorphism of cytokine and innate immunity genes associated with bovine brucellosis in cattle.

Genetic susceptibility to brucellosis is multifactorial, and it is known that impairment of the immune system could contribute to risk for getting brucellosis. The aim of the study was to find association of bovine brucellosis with 20 SNPs pertaining to bovine cytokine (IFNG, IFNGR1, IFNGR2, TNFA) and innate immunity (SLC11A1, TLR1, TLR4, and TLR9) genes using PCR-RFLP genotyping technique and it was observed that SLC11A1 (+1066 C/G), TLR1 (+1446 C/A), TLR1 (+1380 G/A), TLR4 (+10 C/T) and TLR4 (+399 C/T) loci were significantly (P≤0.05) associated with bovine brucellosis. The odds ratios (OR) of CG and CC genotypes versus GG genotype were 0.31 (0.12-0.82; 95% CI) and 0.18 (0.03-1.06; 95% CI) at SLC11A1 (+1066 C/G) locus in cases of brucellosis affected cattle. For TLR1 (+1380 G/A) locus, the OR for AG and AA genotypes versus GG genotypes were 0.15 (0.05-0.44; 95% CI) and 0.26 (0.04-1.47; 95% CI) which indicated that proportion of GG homozygote was significantly higher in brucellosis affected animals as compared to control. At TLR1 (+1446 C/A) locus the OR of AC genotype versus CC genotype was 0.24 (0.08-0.68; 95% CI) which revealed that relative proportion CC genotypes was significantly higher in case population. The TLR4 (+10 C/T) locus had three genotypes (TT, CT and CC) where OR of CT and CC genotypes versus TT genotype were near to zero. The OR of CT genotypes versus CC genotypes was 8.25 (0.94-71.92; 95% CI) at TLR4 (+399 C/T) locus and indicated that CT genotype had higher odds of bovine brucellosis than control animals.

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

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.