Abstract
Vaccine delivery is critical in antigen discovery and vaccine efficacy and safety. The diversity of infectious diseases in humans and livestock has required the development of varied delivery vehicles to target different pathogens. In livestock animals, previous strategies for the development of coccidiosis vaccines have encountered several hurdles, limiting the development of multiple species vaccine formulations. Here, we describe a novel vaccine delivery system using transgenic Eimeria tenella expressing immunodominant antigens of Eimeria maxima. In this delivery system, the immune mapped protein 1 of E. maxima (EmIMP1) was delivered by the closely related species of E. tenella to the host immune system during the whole endogenous life cycle. The overexpression of the exogenous antigen did not interfere with the reproduction and immunogenicity of transgenic Eimeria. After immunization with the transgenic parasite, we detected EmIMP1’s and E. maxima oocyst antigens’ specific humoral and cellular immune responses. In particular, we observed partial protection of chickens immunized with transgenic E. tenella against subsequent E. maxima infections. Our results demonstrate that the transgenic Eimeria parasite is an ideal coccidia antigen delivery vehicle and represents a new type of coccidiosis vaccines. In addition, this model could potentially be used in the development of malaria live sporozoite vaccines, in which antigens from different strains can be expressed in the vaccine strain.
Highlights
Apicomplexan genera parasites that cause serious human, veterinary, or zoonotic diseases include Plasmodium, Toxoplasma, Eimeria, Neospora, and Theileria [1,2,3,4]
We found no significant difference between Et-EmIMP1, its wildtype immunized birds or the transgenic control (EtER) for the E. tenella oocyst antigens (Et Ag)-specific in IFN-γ secreting cells in peripheral blood mononuclear cells (PBMCs) (Figures 3A,B)
We demonstrate that transgenic Eimeria parasites used as vaccine delivery model expressing antigen of its affinis species effectively elicited long periods of foreign pathogen-specific protective immune responses, protecting the host against challenges with wild-type paternal and its affinis species
Summary
Apicomplexan genera parasites that cause serious human, veterinary, or zoonotic diseases include Plasmodium, Toxoplasma, Eimeria, Neospora, and Theileria [1,2,3,4]. There is risk of potential drug residues in poultry meat that threaten food security Both problems constitute major limitations of anti-coccidiosis drugs [6, 7]. Vaccination with formulations containing either the virulent or the attenuated live parasites has been considered the most efficient method for the protection of breeder and layer flocks from Eimeria spp. infection, preventing the presence of drug residues in poultry productions [8, 9]. Vaccinated chicks with one Eimeria species showed complete defense against subsequent homogeneous infection after self-boosting, but not against heterogeneous parasites [7, 9, 10]. Reduction of live parasites formulations, especially of the pathogenic species of the anti-coccidiosis vaccines, can be beneficial in improving animals’ welfare and reducing vaccine production cost
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