Study of cell-mediated immune response induced by HPV DNA vaccine in combination with IL-15 expression plasmid

Objective To investigate the effects of IL-15 eukaryotic expression plasmid on the Ag-specific immune responses induced by HPV 16 E7 vaccine in mice.Methods An eukaryotic expression plasmid encoding IL-15 gene coding region was constructed and named as pcDNA3.1IL-15.Female BALB/c mice were injected intramuscularly with pcDNA3.1-IL-15 and HPV16 E7 gene vaccine.After the immunization,the concentration of serum IFN-γ were tested.Single-cell suspensions of splenocytes were prepared from mice and were re-stimulated with HPV16 E7 protein.Then,the T cell proliferation assay was measured by the MTT method.Results The concentration of serum IFN-γ in mice after co-injection with pcDNA3.1-IL-15 and pcDNA3.1-E7 was raised to 414.1pg/ml,which was significantly higher than that of mice co-injected with pcDNA3.1 and pcDNA3.1-E7 or mice injected with pcDNA3.1-E7 only(P0.01).Administration of pcDNA3.1-IL15 in combination with pcDNA3.1-E7 enhanced specific T cell proliferation(the disparity vale of OD(570) is 1.313),which was statistically significant in comparison with the control group(P0.01).Conclusions Administration of the eukaryotic expression plasmid pcDNA3.1-IL-15 in combination with pcDNA3.1-E7 can enhance cell-mediated responses in mice induced by pcDNA3.1-E7 DNA vaccine.