Bovine PGLYRP1 polymorphisms and their association with resistance to Mycobacterium avium ssp. paratuberculosis

Mycobacterium avium ssp. paratuberculosis (MAP) causes a chronic, granulomatous inflammatory condition of the intestines in ruminants and wild-type species. It causes significant economic losses to the dairy and beef industries owing to reduced productivity, premature culling and mortality. Bovine peptidoglycan recognition protein 1 is an important pattern recognition molecule that is capable of directly killing microorganisms. The goal of this study was to identify single nucleotide polymorphisms (SNPs) in the gene encoding bovine peptidoglycan recognition protein 1 and to assess their association with susceptibility to MAP infection in dairy cattle. Blood and milk samples were collected from Holsteins in Southwestern and Eastern Ontario and tested for MAP infection using blood and milk ELISAs. A resource population consisting of 197 infected (S/P > 0.25) and 242 healthy (S/P < 0.10) cattle was constructed. Sequencing of pooled DNA was used to identify three SNPs (c.102G>C, c.480G>A and c.625C>A) that were genotyped in the resource population. Statistical analysis was performed using a logistic regression model fitting the additive and dominance effects of each SNP in the model. SNP c.480G>A (P = 0.054) was found to be associated with susceptibility to MAP infection. Cows with a copy of the major allele 'G' at this locus had an odds ratio of 1.51 (95% CI: 0.99-2.31) for being infected with MAP.