Induction of protective immunity against experimental Eimeria tenella infection using serum exosomes.
Avian coccidiosis is caused by Eimeria, a unicellular, apicomplexan protist which primarily infects intestinal epithelia resulting in nutrient malabsorption and reduced growth of commercial poultry. Vaccination of chickens with exosomes isolated from antigen presenting cells containing parasite antigens (Ags) represents a promising alternative strategy to control avian coccidiosis, but is restricted in its commercial application due to limitations on production scale-up for mass immunization programs. Here, we report the biochemical and physiologic characteristics of exosomes derived from serum of Eimeria tenella-infected chickens and their feasibility for inducing protective immunity to experimental coccidiosis. Exosomes isolated from the serum of E. tenella-infected chickens contained a subset of protein Ags found in the intact parasite. Serum-derived exosomes containing these E. tenella Ags localized to the intestine and spleen following intramuscular injection into naïve chickens. In vitro ELISPOT assays revealed increased numbers of IL-2-, IL-4-, IL-6-, and IFN-γ-secreting cells in the intestine and spleen of exosome-administered chickens, compared with vehicle controls. Pre-immunization of chickens with serum exosomes from E. tenella-infected chickens increased both body weight gain and feed conversion efficiency, and reduced both fecal parasite shedding and gut lesion scores following parasite infection, compared with vehicle controls. Finally, immunization with CD80(+) serum exosomes stimulated greater numbers of cytokine-producing cells, and higher levels of protective immunity to E. tenella infection, compared with CD80(-) exosomes. These results suggest the possibility of producing an effective, parasite-free vaccine against avian coccidiosis under field conditions using serum-derived CD80(+) exosomes containing parasite Ags.
Department of Animal Pathology, Faculty of Veterinary Sciences, University of Zaragoza, Zaragoza, Spain. Electronic address: edelcach@unizar.es.
Emilio
E
Del Cacho
Department of Animal Pathology, Faculty of Veterinary Sciences, University of Zaragoza, Zaragoza, Spain.
Margarita
M
Gallego
Animal Parasitic Diseases Laboratory, Animal and Natural Resources Institute, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, MD, 20705, USA.
Hyun Soon
HS
Lillehoj
Department of Animal Pathology, Faculty of Veterinary Sciences, University of Zaragoza, Zaragoza, Spain.
Joaquin
J
Quilez
Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Erik P
EP
Lillehoj
Department of Animal Pathology, Faculty of Veterinary Sciences, University of Zaragoza, Zaragoza, Spain.
Caridad
C
Sánchez-Acedo
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D000953:Antigens, Protozoan / Q000276:immunology; D003048:Coccidiosis / Q000276:immunology / Q000662:veterinary*; D016786:Eimeria tenella / Q000276:immunology*; D055354:Exosomes / Q000276:immunology*; D007114:Immunization / Q000662:veterinary*; D011201:Poultry Diseases / Q000276:immunology*; D015430:Weight Gain
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan
Chicken; Dendritic cell; Eimeria tenella; Immunity; Serum exosome