14. Transcriptomics Analysis of Katahdin Sheep PBMC with Divergent PFEC EBV.

Abstract This study aimed to investigate the differential immune response in Katahdin ewes with divergent post-weaning fecal egg count (PFEC) estimated breeding values (EBVs). Peripheral mononuclear blood cells (PBMCs) were isolated from whole blood of 10 Katahdin ewes (5 LoKat and 5 HiKat) and stimulated with lipopolysaccharide (LPS). Following isolation, RNA was extracted and sequenced for each animal and results analyzed for differentially expressed genes (DEGs), gene ontology and pathway analysis (FDR ≤ 0.05). A total of 354 DEGs were identified in HiKatLPS compared to HiKatCON, with 185 being downregulated and 169 being upregulated. Most of the enriched pathways were associated with cytokine production regulation of cytokine production and positive regulation of cytokine production. Conversely, 162 DEGs were identified in LoKatLPS compared to LoKatCON, with 110 being downregulated and 52 being upregulated. The most enriched pathways in LoKat were associated with adaptive immune response, positive regulation of response to stimulus and adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains. Results outline the ability of both groups to respond to immunological stimuli but identify the vast difference in the magnitude of response, which favors a more transient response in the LoKat group compared to a sustained response observed in the HiKat ewes.