Effects of canine IL-2 and IL-7 genes on enhancing immunogenicity of canine parvovirus VP2 gene vaccine in mice

Abstract:

Abstract:［Objective］ To investigate the effects of canine interleukin-2 (cIL-2) and cIL-7 genes on enhancing the immunogenicity of canine parvovirus (CPV) VP2 DNA vaccine． ［Methods］The bicistronic vectors of cIL-2 and cIL-7 genes were constructed using the eukaryotic expression vector containing internal ribosome entry site (IRES)． The cIL-2/clL-7 dicistronic vector plus previously constructed vectors，including CPV VP2 DNA vaccine vector，cIL-2 vector and cIL-7 vector，were used to co-immunize mice with different combinations，consisting of VP2 alone，VP2 + cIL-2，VP2+cIL-7 and VP2+cIL-2/cIL-7. The VP2-specific antibody levels in immunized mice were measured by ELISA at different time post-immunization． The proliferation indices and interferon-γ expression were measured by lymphocyte proliferation assay and ELISA，respectively． ［Results］The cIL-2/cIL-7 bicistronic vector was correct and could mediate cIL-2 and cIL-7 gene expression in eukaryotic cells． Immunization results revealed that the antibody titers and the neutralizing antibody levels of the mice co-immunized with VP2+cIL-7/cIL-2 vectors were significantly higher than that with either VP2+cIL-2 vectors or VP2+cIL-7 vectors (P＜0.05)．The lymphocyte proliferation indices of VP2+cIL-7/cIL-2 vector-immunized mice were also higher than that of other two groups although not statistically significant． However，the IFN-γexpression levels of VP2+cIL-7/cIL-2 vector-immunized mice were significantly higher than other immunized mice (P＜0.05)． ［Conclusion］ The cIL-2 and cIL-7 genes showed the significant synergic effects on enhancing the immunogenecity of CPV VP2 DNA vaccine．