Review Article Immune Responses Associated with Resistance to Haemonchosis in Sheep

Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. is paper examines the known immunological and genetic factors associated with sheep resistance to infection by Haemonchus contortus. Such resistance is an inheritable genetic trait (ℎ2, 0.22–0.63) associated with certain sheep breeds. Resistant sheep do not completely reject the disease; they only harbor fewer parasites than susceptible sheep and therefore have a lower fecal egg count. Protective immune response to haemonchosis is an expression of genetic resistance. Genes associated with resistance and susceptibility are described. Genetically resistant sheep have nonspeci�c mechanisms that block the initial colonization by Haemonchus contortus larvae.ese sheep also have an efficacious2 type response (e.g., increases in blood and tissue eosinophils, speci�c IgE class antibodies, mast cells, IL-5, IL-13, and T�