Induction of Cellular Immune Response by DNA Vaccine Coexpressing E. acervulina 3-1E Gene and Mature CHIl-15 Gene

We previously reported that the chimeric DNA vaccine pcDNA-3-1E-linker-mChIL-15, fused through linking Eimeria acervulina 3-1E encoding gene and mature chicken IL-15 (mChIL-15) gene with four flexible amino acid SPGS, could significantly offer protection against homologous challenge. In the present study, the induction of cellular immune response induced by the chimeric DNA vaccine pcDNA-3-1E-linker-mChIL-15 was investigated. Spleen lymphocyte subpopulations were characterized by flow cytometric analysis. The spleen lymphocyte proliferation assays were measured by 3-[4,5-dimethylthiazol-2-y1]-2,5-diphenyltetrazolium bromide (MTT) method. The mRNA profiles of ChIL-2 and ChIFN-γ in spleen were characterized by means of real-time PCR. Chickens immunized with pcDNA-3-1E-linker-mChIL-15 exhibited significant upregulated level of ChIL-2 and ChIFN-γ transcripts in spleen following two immunizations compared with chickens in other groups (P < 0.01). In comparison with pcDNA3.1-immunized and control groups, lymphocyte proliferation, percentage of CD8α (+) cell, and levels of ChIL-2 and ChIFN-γ transcripts in the group immunized with pcDNA-3-1E-linker-mChIL-15 were significantly increased on day 6 following challenge (P < 0.05, P < 0.01, and P < 0.01, resp.). Our data suggested that the fusion antigen 3-1E-linker-mChIL-15 could be a potential candidate for E. acervulina vaccine development.