02635naa a2200253 a 450000100080000000500110000800800410001902200140006002400360007410000180011024501680012826000090029650003310030552014760063665300150211265300100212770000160213770000140215370000170216770000190218470000200220370000150222377301430223810606992020-01-27       2019    bl uuuu     u00u1 u    #d  a2045-23227 a10.1038/s41598-019-55447-62DOI1 aESCRIBANO, C.  aResistance to Haemonchus contortus in Corriedale sheep is associated to high parasite-specific IgA titer and a systemic Th2 immune response.h[electronic resource]  c2019  aArticle history: Received: 21 June 2019 / Accepted: 27 November 2019 / Published: 20 December 2019. Funding information:  We acknowledge the personnel from Uruguayan Wool Secretariat that assisted with animal studies. This project was funded by INIA (Uruguay) and CSIC-VUSP (Uruguay). C.E. was funded by a scholarship by INIA.  aABSTRACT. Gastrointestinal nematode infections, including Haemonchus contortus, are one of the main causes of economic losses to ovine farmers worldwide. In order to contribute to the control of nematode infections and avoid parasite spreading we generated divergent resistant and susceptible sheep breeds and evaluated the adaptive immunity of these animals developed upon experimental infection against H. contortus. The selection of resistant or susceptible animals from the Corriedale Breed has been based on Expected Progeny Differences for faecal egg counts per gram. Furthermore, animals from the resistant Corriedale line were inseminated with imported semen from Australian Rylington Merino rams. Thus, the objective of this work was to analyze the adaptive immune response in both susceptible and resistant obtained lambs. Our results indicate that there is a potent parasite-specific local and systemic immune response in resistant animals and that although susceptible lambs can produce high levels of IgA antibodies during the infection, their antibody response is delayed which, together with an impaired specific-Th2 response, does not contribute to initial parasite elimination. Our results shed light into the immune mechanisms that mediate resistance to H. contortus and could constitute important assets to sheep farmers, not only as a means to detect resistance, but also to enhance the efficiency of selection in stud flocks.  © 2019, The Author(s).  aHAEMONCHUS  aSHEEP1 aSARAVIA, A.1 aCOSTA, M.1 aCASTELLS, D.1 aCIAPPESONI, G.1 aRIET-CORREA, F.1 aFREIRE, T.  tScientific Reports, 1 December 2019, Volume 9, Issue 1, Article number 19579. OPEN ACCESS. Doi: https://doi.org/10.1038/s41598-019-55447-6