The bovine TLR4 gene is an interesting candidate marker for mastitis resistance, since it is involved in neutrophil migration to and from the mammary gland during mastitis. TLR4 detects pathogen ligands, such as the Escherichia coli lipopolysaccharide (LPS) endotoxin and facilitates innate and adaptive immune responses. In the current study, a total of 130 crossbred cows (74 mastitis tolerant and 56 with clinical mastitis) kept at the Cattle and Buffalo Farm, IVRI, Izatnagar, were selected to explore the polymorphism in the co-receptor binding region 2 (CRBR2) fragment of the TLR4 gene. PCR-SSCP and sequence analysis showed two genotypes of the TLR4 gene's CRBR2 fragment, AA and AB, which were polymorphic in both the afflicted and tolerant groups. Sequencing revealed eight single nucleotide polymorphisms (SNPs) in allele A and ten SNPs in allele B. This genotype had no significant effect on the incidence of clinical mastitis according to the logistic regression model. Our study found insufficient evidence linking SNP variants in the CRBR2 region of the TLR4 gene to mastitis susceptibility in crossbred cattle.
Keywords: Association; CRBR2; Mastitis; Polymorphism and TLR4.
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