Specific IgG antibody responses in Oestrus ovis L. (Diptera: Oestridae) infected sheep: Associations with intensity of infection and larval development C.E. Angulo-Valadez a , A. Scala b , C. Grisez c , F. Prevot c , J.P. Bergeaud c , A. Carta d , R. Cepeda-Palacios e , F. Ascencio a , G. Terefe f , P. Dorchies c , P. Jacquiet c, * a Centro de Investigaciones Biolo ´ gicas del Noroeste, Mar Bermejo 195, Col. Playa de Santa Rita, La Paz,B.C.S.23090, Mexico b Section of Parasitology, Department of Animal Biology, University of Sassari, via Vienna 2, 07100 Sassari, Italy c UMR INRA/ENVT 1225 Interactions ho ˆ ts Agents Pathoge ` nes, 23 Chemin des Capelles, 31076 Toulouse Cedex 03, France d Istituto Zootecnico e Caseario per la Sardegna, Sassari-Fertilia, Italy e Laboratorio de Sanidad Animal, Universidad Auto ´ noma de Baja California Sur, Carretera al Sur km. 5.5., Col. Mezquitito, La Paz,B.C.S. 23080, Mexico f Addis Ababa University, Faculty of Veterinary Medicine, P.O. Box 34,Debre-Zeit, Ethiopia Received 16 October 2007; received in revised form 7 May 2008; accepted 12 May 2008 Abstract Larvae of Oestrus ovis (Diptera: Oestridae) are ubiquitous parasites of nasal and sinusal cavities of sheep and to the chronobiology of O. ovis infections in Sardinia and the seasonal pattern of the IgG response, the optimal p the relationships between O. ovis larval populations and intensity of local and systemic IgG antibody responses w summer season. Sarda Lacaune ewes (n = 186), divided into three ram-families were used in the study. System responses were measured by ELISA tests using second stage larval crude extracts (L2CE) and L2 (L2SGC) and L3 salivary gland contents as coating antigens. The number of larval instars, larval length of L1, L2 and L3 larvae, a L2 and L3 larvae were individually recorded after ewe necropsy. Negative correlations among larval establishme development on the one hand and intensity of local or systemic IgG responses on the other hand were found in studied ram-families. # 2008 Elsevier B.V. All rights reserved. Keywords: Oestrus ovis; Salivary gland; Sheep; Immunoglobulin G; Larval growth; Genetic resistance; ELISA 1. Introduction Larvaeof Oestrusovis (Diptera:Oestridae) are common parasites of the nasal and sinusal cavities of sheep and goats (Dorchies et al.,2000;Scala etal., 2001) causing losses in meat, wool and milk product Nasal dischargesand sneezingfrequentlyseenin summer are the major clinical signs in O. ovis infecte sheep. Female adults deposit first-instar larvae (L1) i the host nostrils where they quickly crawl into the na cavities. First stage larvae (L1) migrate from the nas septum and turbinates to the ethmoid where the firs moult to the second stage larvae (L2) occurs. Then, L www.elsevier.com/locate/vetpar Available online at www.sciencedirect.com Veterinary Parasitology 155 (2008) 257–263 * Corresponding author. Tel.: +33 5 61193967; fax: +33 5 61193944. E-mail address: p.jacquiet@envt.fr (P. Jacquiet). 0304-4017/$ – see front matter # 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2008.05.015