Genome-wide association studies of parasite resistance, productivity and immunology traits in Scottish Blackface sheep

• Published in: Animal (Cambridge, England) England), 2024-02, Vol.18 (2), p.101069-101069, Article 101069
• Main Authors: Pacheco, A., Banos, G., Lambe, N., McLaren, A., McNeilly, T.N., Conington, J.
• Format: Article
• Language: English
• Subjects: Animals; Breeding; Feces - parasitology; Gastrointestinal parasites; Genome-Wide Association Study - veterinary; Genomic analysis; Immunity; Immunoglobulin A; Interleukin-10; Parasite Egg Count - veterinary; Parasites - genetics; Scotland; Sheep; Sheep - genetics; Sheep Diseases - parasitology; Sheep, Domestic - genetics
• ISSN: 1751-7311; 1751-732X
• DOI: 10.1016/j.animal.2023.101069

•Genomic analysis of traits associated with parasite resistance in sheep.•Focus on novel traits of cytokine production in addition to Immunoglobulin A and faecal counts.•Multiple genes were identified involved in immunological functions.•We note the importance of genes around the Major Histocompatibility Complex.•Insights into candidate regions may result in an increased accuracy of selection. Gastrointestinal parasitism represents a global problem for grazing ruminants, which can be addressed sustainably by breeding animals to be more resistant against infection by parasites. The aim of this study was to assess the genetic architecture underlying traits associated with gastrointestinal parasite resistance, immunological profile and production in meat sheep, and identify and characterise candidate genes affecting these traits. Data on gastrointestinal parasite infection (faecal egg counts for Strongyles (FECS) and Nematodirus (FECN) and faecal oocyst counts for Coccidia, along with faecal soiling scores (DAG), characterised by the accumulation of faeces around the perineum) and production (live weight (LWT)) were gathered from a flock Scottish Blackface lambs at three and four months of age. Data on the immune profile were also collected from a subset of these lambs at two and five months of age. Immune traits included the production of Interferon-γ (IFN-γ), Interleukin (IL)-4 and IL-10 following stimulation of whole blood with pokeweed mitogen (PWM) or antigen from the gastric parasite Teladorsagia circumcincta (T-ci), and serum levels of T. circumcincta-specific immunoglobulin A (IgA). Animals were genotyped with genome-wide DNA arrays, and a total of 1 766 animals and 45 827 Single Nucleotide Polymorphisms (SNPs) were retained following quality control and imputation. Genome-wide association studies were performed for 24 traits. The effects of individual markers with significant effects were estimated, and the genotypic effect solutions were used to estimate additive and dominance effects, and the proportion of additive genetic variance attributed to each SNP locus. A total of 15 SNPs were associated at least at a suggestive level with FECS, FECN, DAG, IgA, PWM-induced IFN-γ and IL-4, and T-ci-induced IL-10. This study uncovered 52 genes closely related to immune function in proximity to these SNPs. A number of genes encoding C-type lectins and killer cell lectin-like family members were close to a SNP associated with FECN, while several genes encoding