Transgenic Eimeria mitis expressing chicken interleukin 2 stimulated higher cellular immune response in chickens compared with the wild-type parasites

Abstract

Chicken coccidiosis, caused by Eimeria sp., occurs in almost all poultry farms and causes huge economic losses in the poultry industry. Although this disease could be controlled by vaccination, the reduced feed conservation ratio limits the widespread application of anticoccidial vaccines in broilers because some intermediate and/or low immunogenic Eimeria sp. only elicit partial protection. It is of importance to enhance the immunogenicity of these Eimeria sp. by adjuvants for more effective prevention of coccidiosis. Cytokines have remarkable effects on the immunogenicity of antigens. Interleukin 2 (IL-2), for example, significantly stimulates the activation of CD8+ T cells and other immune cells. In this study, we constructed a transgenic Eimeria mitis line (EmiChIL-2) expressing chicken IL-2 (ChIL-2) to investigate the adjuvant effect of ChIL-2 to enhance the immunogenicity of E. mitis against its infection. Stable transfected EmiChIL-2 population was obtained by pyrimethamine selection and verified by PCR, genome walking, western blotting and indirect immunofluorescence assay. Cellular immune response, E. mitis-specific IFN-γ secretion lymphocytes in the peripheral blood mononuclear cells, stimulated by EmiChIL-2 was analyzed by enzyme-linked immunospot assay (ELISPOT). The results showed that EmiChIL-2 stimulated a higher cellular immune response compared with that of the wild-type parasite infection in chickens. Moreover, after the immunization with EmiChIL-2, elevated cellular immune response as well as reduced oocyst output were observed These results indicated that ChIL-2 expressed by Eimeria sp. functions as adjuvant and IL-2 expressing Eimeria parasites are valuable vaccine strains against coccidiosis.

Transgenic Eimeria magna Pérard, 1925 Displays Similar Parasitological Properties to the Wild-type Strain and Induces an Exogenous Protein-Specific Immune Response in Rabbits (Oryctolagus cuniculus L.)

“…However, a significant local immunity in the MLN was detected. Previous work in our laboratory (8) on transgenic chicken Eimeria demonstrated that enhanced cellular immunity was detected in PBMC of chickens immunized with transgenic parasites expressing chicken IL-2. However, the systemic immune response, at least in our rabbits, was low after primary infection of EmagWT or EmagER , consistent with a previous study on the dynamics of T-lymphocytes in rabbits immunized with E. intestinalis (28).…”

“…Previous studies demonstrated that the exogenous protein expressed by transgenic parasites stimulate specific immune responses in the host. One study (8) showed that immunization with a transgenic E. mitis line expressing chicken IL-2 stimulated an enhanced cellular immune response against it. In addition, a transgenic line of E. tenella expressing Toxoplasma gondii SAG1 protein (TgSAG1) elicits protective immunity against T. gondii in chicken and mice (9).…”

Transgenic Eimeria tenella Expressing Profilin of Eimeria maxima Elicits Enhanced Protective Immunity and Alters Gut Microbiome of Chickens

“…Genetic manipulation to improve the safety and efficacy of anticoccidiosis vaccines have been extensively studied in recent years (28)(29)(30)(31). Enhancing the immunogenicity of live oocyst formulations via expressing molecular adjuvants is one of the most active and promising attempts (29,30).…”

“…Genetic manipulation to improve the safety and efficacy of anticoccidiosis vaccines have been extensively studied in recent years (28)(29)(30)(31). Enhancing the immunogenicity of live oocyst formulations via expressing molecular adjuvants is one of the most active and promising attempts (29,30). Li and colleagues used interleukin 2 (IL-2), a critical cytokine for T cell activation and proliferation, to enhance the immunogenicity of E. mitis and demonstrated that the protection provided by transgenic E. mitis expressing IL-2 is nearly 3-fold better than that provided by the wild type in experimental settings (29).…”

“…Enhancing the immunogenicity of live oocyst formulations via expressing molecular adjuvants is one of the most active and promising attempts (29,30). Li and colleagues used interleukin 2 (IL-2), a critical cytokine for T cell activation and proliferation, to enhance the immunogenicity of E. mitis and demonstrated that the protection provided by transgenic E. mitis expressing IL-2 is nearly 3-fold better than that provided by the wild type in experimental settings (29). Parallel experiments showed that transgenic Eimeria expressing the Fc fragment of immunoglobulin stimulated better protective immunity than its wild type (30).…”