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

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). The findings revealed that the inoculation of the 14-day-old chickens exhibited a shorter time to achieve the highest HI titer in comparison to the inoculation of the 1-day-old chickens. The cellular immunity was assessed by the flow cytometry analysis to enumerate CD4+ and CD8 + T cells in the peripheral blood. The chickens inoculated with pDis/H5？+？pDis/IL-15 demonstrated the highest increase in CD4+ T cells population relative to the control chickens. However, this study revealed that pDis/H5？+？pDis/IL-15 was not significant (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). On the other hand, the pDis/H5？+？pDis/IL-18 group was not significant (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？<？0.05). Similar results were obtained for the IL-18 expression where the pDis/H5？+？pDis/IL-18 groups in both trials (Table 8) were significantly higher compared to the control group (P？<？0.05). However, the expressions of other cytokines remained low or undetected by GeXP assay.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.Avian influenza (AI) is regarded as one of the most important diseases infecting poultry and other birds throughout the world. Outbreaks of H5N1, the highly pathogenic avian influenza (HPAI), in poultry all over Asia have caused significant economic and public health difficulties [1]. Traditionally, the control of th