Abstract
BackgroundGastrointestinal nematodes are one of the most serious causes of disease in domestic ruminants worldwide. There is considerable variation in resistance to gastrointestinal nematodes within and between sheep breeds, which appears to be due to underlying genetic diversity. Through selection of resistant animals, rapid genetic progress has been demonstrated in both research and commercial flocks. Recent advances in genome sequencing and genomic technologies provide new opportunities to understand the ovine host response to gastrointestinal nematodes at the molecular level, and to identify polymorphisms conferring nematode resistance.ResultsDivergent lines of Romney and Perendale sheep, selectively bred for high and low faecal nematode egg count, were genotyped using the Illumina® Ovine SNP50 BeadChip. The resulting genome-wide SNP data were analysed for selective sweeps on loci associated with resistance or susceptibility to gastrointestinal nematode infection. Population differentiation using FST and Peddrift revealed sixteen regions, which included candidate genes involved in chitinase activity and the cytokine response. Two of the sixteen regions identified were contained within previously identified QTLs associated with nematode resistance.ConclusionsIn this study we identified fourteen novel regions associated with resistance or susceptibility to gastrointestinal nematodes. Results from this study support the hypothesis that host resistance to internal nematode parasites is likely to be controlled by a number of loci of moderate to small effects.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-637) contains supplementary material, which is available to authorized users.
Highlights
Gastrointestinal nematodes are one of the most serious causes of disease in domestic ruminants worldwide
With wide variability among individuals, and rapid genetic progress has been demonstrated in both research and commercial flocks [6,7]
Quality control After quality control the final data set consisted of 46,736 Single Nucleotide Polymorphisms (SNP) for the Romney data set and 48,436 SNP for the Perendale data set
Summary
Gastrointestinal nematodes are one of the most serious causes of disease in domestic ruminants worldwide. There is considerable variation in resistance to gastrointestinal nematodes within and between sheep breeds, which appears to be due to underlying genetic diversity. Through selection of resistant animals, rapid genetic progress has been demonstrated in both research and commercial flocks. In the face of the increasing incidence of anthelmintic resistance and the need to minimise drench residues in animal products, new strategies for control are required [4]. Breeding for host resistance has been shown to be a viable method of nematode control [5]. With wide variability among individuals, and rapid genetic progress has been demonstrated in both research and commercial flocks [6,7]. Computer simulation models have shown that selection for host resistance, using the phenotype low faecal worm
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