title: Developing a preventive immunization approach against insect bite hypersensitivity using recombinant allergens: A pilot study.
abstract: Insect bite hypersensitivity (IBH) is an allergic dermatitis of horses caused by bites of midges (Culicoides spp.). IgE-mediated reactions are often involved in the pathogenesis of this disease. IBH does not occur in Iceland due to the absence of Culicoides, but it occurs with a high frequency in Icelandic horses exported to mainland Europe, where Culicoides are present. We hypothesize that immunization with the Culicoides allergens before export could reduce the incidence of IBH in exported Icelandic horses. The aim of the present study was therefore to compare intradermal and intralymphatic vaccination using four purified recombinant allergens, in combination with a Th1 focusing adjuvant. Twelve horses were vaccinated three times with 10μg of each of the four recombinant Culicoides nubeculosus allergens. Six horses were injected intralymphatically, three with and three without IC31(®), and six were injected intradermally, in the presence or absence of IC31(®). Antibody responses were measured by immunoblots and ELISA, potential sensitization in a sulfidoleukotriene release test and an intradermal test, cytokine and FoxP3 expression with real time PCR following in vitro stimulation of PBMC. Immunization with the r-allergens induced a significant increase in levels of r-allergen-specific IgG1, IgG1/3, IgG4/7, IgG5 and IgG(T). Application of the r-allergens in IC31(®) adjuvant resulted in a significantly higher IgG1, IgG1/3, IgG4/7 allergen-specific response. Intralymphatic injection was slightly more efficient than intradermal injection, but the difference did not reach significance. Testing of the blocking activity of the sera from the horses immunized intralymphatically with IC31(®) showed that the generated IgG antibodies were able to partly block binding of serum IgE from an IBH-affected horse to these r-allergens. Furthermore, IgG antibodies bound to protein bands on blots of C. nubeculosus salivary gland extract. No allergen-specific IgE was induced and there was no indication of induction of IgE-mediated reactions, as horses neither responded to Culicoides extract stimulation in a sulfidoleukotriene release test, nor developed a relevant immediate hypersensitivity reaction to the recombinant allergens in skin test. IL-4 expression was significantly higher in horses vaccinated intralymphatically without IC31(®), as compared to horses intradermally vaccinated with IC31(®). Both routes gave higher IL-10 expression with IC31(®). Both intralymphatic and intradermal vaccination of horses with recombinant allergens in IC31(®) adjuvant induced an immune response without adverse effects and without IgE production. The horses were not sensitized and produced IgG that could inhibit allergen-specific IgE binding. We therefore conclude that both the injection routes and the IC31(®) adjuvant are strong candidates for further development of immunoprophylaxis and therapy in horses.
authors.affiliation: Institute for Experimental Pathology, Biomedical Center, University of Iceland, Keldur, Keldnavegur 3, 112 Reykjavik, Iceland. Electronic address: sij9@hi.is.
authors.forename: Sigridur
authors.initials: S
authors.lastname: Jonsdottir
authors.affiliation: Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Berne, Länggassstrasse 124, 3012 Berne, Switzerland.
authors.forename: Eman
authors.initials: E
authors.lastname: Hamza
authors.affiliation: Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Berne, Länggassstrasse 124, 3012 Berne, Switzerland.
authors.forename: Jozef
authors.initials: J
authors.lastname: Janda
authors.affiliation: Swiss Institute of Allergy and Asthma Research (SIAF), Davos, Switzerland.
authors.forename: Claudio
authors.initials: C
authors.lastname: Rhyner
authors.affiliation: Valneva Austria GmbH, Campus Vienna Biocenter 3, 1030 Vienna, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Meinke
authors.affiliation: Department of Clinical Research and Veterinary Public Health, Vetsuisse Faculty, University of Berne, Länggassstrasse 124, 3012 Berne, Switzerland.
authors.forename: Eliane
authors.initials: E
authors.lastname: Marti
authors.affiliation: Institute for Experimental Pathology, Biomedical Center, University of Iceland, Keldur, Keldnavegur 3, 112 Reykjavik, Iceland.
authors.forename: Vilhjalmur
authors.initials: V
authors.lastname: Svansson
authors.affiliation: Institute for Experimental Pathology, Biomedical Center, University of Iceland, Keldur, Keldnavegur 3, 112 Reykjavik, Iceland.
authors.forename: Sigurbjorg
authors.initials: S
authors.lastname: Torsteinsdottir
mesh_terms: D000485:Allergens / Q000276:immunology*; D000818:Animals; D004338:Drug Combinations; D006736:Horses; D006967:Hypersensitivity / Q000517:prevention & control*; D007114:Immunization; D007074:Immunoglobulin G / Q000097:blood / Q000145:classification; D007299:Insect Bites and Stings / Q000276:immunology*; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D010865:Pilot Projects; D011994:Recombinant Proteins / Q000276:immunology
chemical_list: D000485:Allergens; D004338:Drug Combinations; C544002:IC31 adjuvant; D007074:Immunoglobulin G; D009838:Oligodeoxyribonucleotides; D009842:Oligopeptides; D011994:Recombinant Proteins
keywords: Horse; IgG subclasses; Immunotherapy; Insect bite hypersensitivity; Intradermal; Intralymphatic