Co-administration of avian influenza virus H5 plasmid DNA with chicken IL-15 and IL-18 enhanced chickens immune responses

Abstract Background DNA vaccines offer several advantages over conventional vaccines in the development of effective vaccines against avian influenza virus (AIV). However, one of the limitations of the DNA vaccine in poultry is that it induces poor immune responses. In this study, chicken interleukin (IL) -15 and IL-18 were used as genetic adjuvants to improve the immune responses induced from the H5 DNA vaccination in chickens. The immunogenicity of the recombinant plasmid DNA was analyzed based on the antibody production, T cell responses and cytokine production, following inoculation in 1-day-old (Trial 1) and 14-day-old (Trial 2) specific-pathogen-free chickens. Hence, the purpose of the present study was to explore the role of chicken IL-15 and IL-18 as adjuvants following the vaccination of chickens with the H5 DNA vaccine. Results The overall HI antibody titer in chickens immunized with pDis/H5 + pDis/IL-15 was higher compared to chickens immunized with pDis/H5 (p 0.05) in inducing CD8+ T cells. Meanwhile, with the exception of Trial 1, the flow cytometry results for Trial 2 demonstrated that the pDis/H5 + pDis/IL-18 inoculated group was able to trigger a higher increase in CD4+ T cells than the pDis/H5 group (P 0.05) in modulating CD8+ T cells population in both trials. The pDis/H5 + pDis/IL-15 inoculated group showed the highest IL-15 gene expression in both trials compared to other inoculated groups (P Conclusions This study shows the diverse immunogenicity of pDis/H5 co-administered with chicken IL-15 and IL-18,with pDis/H5 + pDis/IL-15 being a better vaccine candidate compared to other groups.