Single-nucleotide polymorphisms in CLEC7A, CD209 and TLR4 gene and their association with susceptibility to paratuberculosis in Indian cattle

The aim of this study was to identify the single-nucleotide polymorphisms (SNPs) in bovine candidate genes CLEC7A, CD209 and TLR4, and explore the association between these SNPs with the occurrence of bovine paratuberculosis (PTB) disease. For this purpose, 549 animals were screened by a panel of four diagnostic tests, namely Johnin PPD test, ELISA test, faecal microscopy and IS900 blood PCR against Mycobacterium avium ssp. paratuberculosis (MAP) to develop case-control populations. SNPs were genotyped by polymerase chain reaction-restriction fragment length polymorphism method. Genotypic-phenotypic associations were assessed by the PROC-LOGISTIC procedure of SAS 9.3. Of the seven SNPs; rs110353594 in CLEC7A gene and rs8193046 in TLR4 gene were found to be associated with PTB. For SNP rs110353594, odds of CC and CT genotypes vs TT genotype was 1.543 (0.420-5.667; 95% CI) and 0.284 (0.104-0.774; 95% CI), respectively which means that CT genotype was more resistant than TT and CC genotypes against bovine PTB. For SNP rs8193046, odds of AA and AG genotypes versus GG genotype was 0.947 (0.296-3.034; 95% CI) and 3.947 (1.555-10.022; 95% CI), respectively, i.e. probability for getting an infection in animals with AG genotype was 3.94 times more as compared to GG genotype. Hence, a selection programme favouring CT genotype for rs110353594 and against AG genotype for rs8193046 may be beneficial for conferring resistance against bovine PTB.