title: Regulation of Oestrus ovis (Diptera: Oestridae) populations in previously exposed and naïve sheep.
abstract: Larvae of Oestrus ovis (Insecta: Diptera: Oestridae) are common parasites of nasal and sinus cavities of sheep and goats. During larval development, a specific immune reaction is initiated by the host with a humoral local and systemic response and the recruitment of eosinophils and mast cells in the upper airways mucosae. Nevertheless, the roles of these responses in the regulation of O. ovis larvae populations in sheep are not yet known. The aim of this study was to compare the establishment and the development of larvae as well as some inflammatory or immune parameters between different groups of half-sibling sheep: (i) a primed group experimentally infected twice before a challenge infection, (ii and iii) two groups infected once only and previously treated with a long-lasting corticoïd before the challenge (one group) or not (the other group). A fourth group of non-infected animals was added in the experimental design. The larval establishment rate was 23% in the corticoïd treated group compared to about 10% in the two other infected groups. Moreover, the larval development appeared more rapid in the corticoïd treated group than in the two other infected groups suggesting that the inflammatory response is involved in the regulation of O. ovis populations. By contrast, no differences in the establishment rates were shown in the primed group compared to the naïve group (without corticoïd treatment) despite evidence of higher eosinophilia, serum specific IgG, and immediate hypersensibility to excretory-secretory products of larvae. The specific lymphocyte proliferation was reduced in the primed group compared to the naïve one suggesting that an immuno-suppression occurs following repetitive O. ovis infections.
authors.affiliation: UMR INRA/DGER 1225 Interactions Hôtes--Agents Pathogènes, Ecole Nationale Vétérinaire de Toulouse, 23, Chemin des Capelles, 31 076 Toulouse Cedex 03, France. p.jacquiet@envt.fr
authors.forename: Philippe
authors.initials: P
authors.lastname: Jacquiet
authors.forename: Trinh
authors.initials: T
authors.lastname: Tran Thi Ngoc
authors.forename: Xavier
authors.initials: X
authors.lastname: Nouvel
authors.forename: Françoise
authors.initials: F
authors.lastname: Prevot
authors.forename: Christelle
authors.initials: C
authors.lastname: Grisez
authors.forename: Hailu Tolossa
authors.initials: HT
authors.lastname: Yacob
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Bergeaud
authors.forename: Hervé
authors.initials: H
authors.lastname: Hoste
authors.forename: Philippe
authors.initials: P
authors.lastname: Dorchies
authors.forename: Guillaume
authors.initials: G
authors.lastname: Tabouret
mesh_terms: D000305:Adrenal Cortex Hormones / Q000494:pharmacology; D000818:Animals; D049109:Cell Proliferation; D004175:Diptera / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D004802:Eosinophilia / Q000453:epidemiology / Q000469:parasitology; D005260:Female; D006632:Histamine / Q000276:immunology; D006969:Hypersensitivity, Immediate / Q000276:immunology / Q000469:parasitology / Q000662:veterinary; D007074:Immunoglobulin G / Q000097:blood; D007963:Leukocytes, Mononuclear / Q000276:immunology; D009198:Myiasis / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D009297:Nasal Mucosa / Q000276:immunology / Q000469:parasitology; D009668:Nose Diseases / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D011897:Random Allocation; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology / Q000469:parasitology*
chemical_list: D000305:Adrenal Cortex Hormones; D007074:Immunoglobulin G; D006632:Histamine