Co-administration of inactivated avian influenza virus with CpG or rIL-2 strongly enhances the local immune response after intranasal immunization in chicken

Intranasal delivery of vaccines is the most effective means of inducing effective immunity in the upper respiratory tract as well as other mucosal lymphoid tissues. To evaluate the effects of the H5N2 inactivated virus with adjuvant, 120 one-day-old chicks were intranasal immunized with the H5N2 inactivated virus respectively mixed with adjuvant CpG or recombinant IL-2 (rIL-2). The local immunocompetent cells on the respiratory tract were detected. The results showed that the number of intraepithelial lymphocytes (IELs), CD3+ T lymphocytes and mast cells in respiratory tract increased significantly respectively and the number of IgA and IgG secreting cells increased significantly after immunization. However, there was no significant change in the immunocompetent cells of the animals administrated H5N2 inactivated virus alone compared to the control group. Our results indicated that intranasal administration of H5N2 inactivated virus with adjuvant CpG or rIL-2 could be beneficial to the local immune response in the respiratory tract.