Detecting Copy Number Variation Associated with Gastrointestinal Parasites in Corriedale Sheep

Several studies have reported an association between copy number variation (CNV) and various diseases and complex trait phenotypes in different species. The objective of the present study was to detect CNV associated with gastrointestinal parasite (GIP) infection in sheep. A total of 54 resistant (R) and 44 susceptible (S) Corriedale sheep, from divergent selection lines for R/S to GIP, were selected by extreme fecal worm egg count breeding values and average relatedness coefficient (<4%). All DNA samples were genotyped using the Illumina OvineSNP50 BeadChip. Additionally, two whole genome sequences were performed from pooled DNA of 4 R and 4 S individuals, respectively. Based on SNP luminescence intensities (expressed as Log₂ Ratio) differences between R and S lines, 60 SNPs were selected as CNV candidates. From these markers, 54 matched with the sheep genomes v2.0 and v3.1 (with a similarity coefficient > 0.9), of which 14 of them had at least two fold coverage differences between R and S. These results provide valuable information for further study of sheep CNV underling R/S to GIP. Validation of CNVs using quantitative PCR is underway.