| Inflammatory diseases like mastitis and Johne's diseases (JD) cause major economic losses in dairy cattle production. Both diseases have bacterial etiologies and though mastitis is etiologically complex, JD is specifically caused by Mycobacterium avium ssp. paratuberculosis (MAP). Therapeutic and prophylactic strategies to deal with these diseases are expensive, ineffective or inefficient. Since susceptibility to both diseases is known to be heritable, variation in host genetics could potentially influence disease resistance. Identification of such genetic variants could enable the selection of dairy cattle for increased resistance to mastitis and JD and minimize the associated economic losses. Host pattern recognition molecules (PRMs) are interesting candidates in this regard as they recognize conserved pathogen-associated molecular patterns (PAMPs) shared by a wide range of pathogens and modulate the host immune responses against them. Previous studies have demonstrated that SNPs in different PRMs could impair an individual's ability to respond properly to infections. Therefore, the aim of this study was to investigate the presence of single nucleotide polymorphisms (SNPs) in important PRMs: Toll-like receptor 2 (TLR2 ), Caspase recruitment domain 15 (CARD15), Peptidoglycan recognition protein 1 (PGLYRP1) and Dectin-1 (CLEC7A ), and study their associations with somatic cell score (SCS), an indirect index of mastitis resistance, and MAP infection status in dairy cattle. Since little is known about genomic regions that influence MAP infection status in dairy cattle, the aim of this study was also to investigate the presence of chromosomal regions influencing MAP infection status in a genome-wide association (GWA) study. SNPs were identified by sequencing of a pooled DNA sample and separate resource populations were genotyped for evaluating associations with SCS and MAP infection status. The BovineSNP50 BeadChip containing 54,001 SNPs was used to genotype 232 animals with known MAP infection status in order to perform the GWA study. Associations between SNP c.3020A>T in CARD15 and SCS, and between SNP c.480G>A in PGLYRP1; SNP c.616G>A in CLEC7A and MAP infection status were found. The GWA analyses revealed the presence of at least 12 genomic regions on BTA1, 5, 6, 7, 10, 11 and 14 that were associated with the MAP infection status of our resource population. |
