|KIM, EUI-SOO - Iowa State University|
|VINICIUS DA SILVA, MARCOS - Embrapa|
|Van Tassell, Curtis - Curt|
Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2015
Publication Date: 3/24/2015
Citation: Kim, E., Sonstegard, T.S., Vinicius Da Silva, M., Gasbarre, L.C., Van Tassell, C.P. 2015. Genome-wide scan of gastrointestinal nematode resistance in closed Angus population selected for minimized influence of MHC. PLoS One. 10(3):e0119380.
Interpretive Summary: This report is a continuation of a previous study in a resource population of Angus cattle to try to identify genomic regions or genes affecting host genetic response to parasitic infection. In the first study, the regions were mapped using older DNA marker technology at a much lower resolution of about 200 markers. In this study, a SNP assay bead chip with DNA markers for 50,000 locations across the genome were analyzed using the phenotypic data collected in a closed experimental Angus population over the past 15 years. The genome wide association analysis identified about 100 locations of significance revealing the complex nature of host resistance to parasites. These results will lead to further studies to identify DNA markers that can be used to guide selection of animals for drug treatment to tolerate parasite infection, thus reducing drug input and costs for the producer.
Technical Abstract: Genetic markers associated with parasite indicator traits are ideal targets for study of marker assisted selection aimed at controlling infections that reduce herd use of anthelminthics. For this study, we collected gastrointestinal (GI) nematode fecal egg count (FEC) data from post weaning animals of an Angus resource population challenged to a 26 week natural exposure on pasture. In all, data from 410 animals was collected over a 12 year period between 1992 and 2007, most of which were selected for a specific DRB1 allele to reduce the influence of gene variant effects derived from this locus. BovineSNP50 genotypes from 410 animals and their ancestors (n=150) were generated for genome-wide association (GWA) tests, which revealed over 100 significant SNP (-log10p value cutoff in the parenthesis) associated with Box- Cox transformed mean FEC. Considering genome-wide association tests, candidate genes involved in immune responses were selected from the significant regions, and some of these genes were found to be participating in inflammatory response. Furthermore, potential effects of selection and inbreeding on associations between genomic regions and resistance to disease were investigated, and found no strong evidence that the regions associated with resistance to parasitic disease have been affected by selection or local autozygosity. These findings may provide useful information for early disease resistance prediction in cattle and suggest new molecular targets for disease-modifying therapies that identify animals most likely to benefit from individualized treatment.