title: Immune responses associated with resistance to haemonchosis in sheep.
abstract: This paper examines the known immunological and genetic factors associated with sheep resistance to infection by Haemonchus contortus. Such resistance is an inheritable genetic trait (h(2), 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 nonspecific mechanisms that block the initial colonization by Haemonchus contortus larvae. These sheep also have an efficacious Th2 type response (e.g., increases in blood and tissue eosinophils, specific IgE class antibodies, mast cells, IL-5, IL-13, and TNFα) that protects them against the infection; in contrast, susceptible sheep do not efficiently establish this type of immune response. Finally, the main reported antigens of H. contortus were reviewed.
authors.affiliation: Departamento de Ciencias Biológicas, Facultad de Estudios Superiores Cuautitlán, Universidad Nacional Autónoma de México, Km. 2.5 Carretera Cuautitlán-Teoloyucan, 54714 Cuautilán Izcalli, MEX, Mexico. fealba@hotmail.com
authors.forename: Fernando
authors.initials: F
authors.lastname: Alba-Hurtado
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Muñoz-Guzmán
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000097:blood; D003165:Complement System Proteins / Q000276:immunology; D060467:Disease Resistance; D004804:Eosinophils / Q000276:immunology / Q000469:parasitology; D005243:Feces / Q000469:parasitology; D006188:Haemonchiasis / Q000235:genetics / Q000276:immunology* / Q000662:veterinary; D006189:Haemonchus; D007113:Immunity, Innate; D007073:Immunoglobulin E / Q000097:blood; D018793:Interleukin-13 / Q000276:immunology; D015848:Interleukin-5 / Q000276:immunology; D010270:Parasite Egg Count / Q000662:veterinary; D012756:Sheep / Q000469:parasitology*; D012757:Sheep Diseases / Q000235:genetics / Q000276:immunology* / Q000469:parasitology; D013045:Species Specificity; D018418:Th2 Cells / Q000166:cytology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: D000909:Antibodies, Helminth; D018793:Interleukin-13; D015848:Interleukin-5; D014409:Tumor Necrosis Factor-alpha; D007073:Immunoglobulin E; D003165:Complement System Proteins