Infection with gastrointestinal nematodes is challenging and costly for sheep producers and impacts the economic efficiency of farms and reduces the welfare of infected animals. There is evidence that resistance to gastrointestinal nematodes is a heritable trait in sheep, and genetic selection for this trait is a novel method for Canadian sheep producers to reduce levels of gastrointestinal nematode infection in their flocks. This thesis sought to identify functional regulatory elements including genes, mRNA isoforms, and long non-coding RNA that regulate the host immune response to gastrointestinal nematode infection in sheep using hepatic tissue collected from animals with various levels of gastrointestinal nematode infection and immune responsiveness. A list of candidate key regulatory genes, mRNA isoforms, and long non-coding RNAs were identified. These candidate regulatory elements may be used in future genomic selection programs to increase the resistance of grazing sheep to infection by gastrointestinal nematodes.