Induction of immune response in mice by combined immunization with HSV-2 multi-epitope DNA vaccines and interleukin-2 genetic adjuvant

Objective To investigate the effect of combined immunization of interleukin-2(IL-2) eDNA and HSV-2 muiti-epitope DNA vaccines on the humeral and cellular immunity of mice.Methods The eukaryotic expression plasmid pcDNA3.1 was used to construct a multi-epitope DNA vaccine HV- pcDNA3.1,which contained the genes of glycoprotein D,glycoprotein B,glycoprotein C and infectious cell protein 27(ICP 27),and a recombinant eukaryotic expression plasmid IL-2-pcDNA3.1.Fifteen C57/BL6 mice were divided into 3 groups immunized with pcDNA3.1 vector,HV-pcDNA3.1 vaccine,and combina- tion of HV-pcDNA3.1 vaccine and IL-2-pcDNA3.1,respectively for 2 times with an interval of 2 weeks. Three weeks after the last immunization,ELISA was used to detect the serum levels of HSV-specifie IgG, IL-2 and IFN-γin these mice,lactate dehydrogenase assay to evaluate the function of CTL,and MTT method to assess the lymphproliferation response of T lymphocytes collected from the spleen of these mice. Results In comparison with the immunization with HV-pcDNA3.1 vaccine alone,the coinjection of IL-2-pcDNA3.1 and HV-pcDNA3.1 increased the serum levels of IFN-γ(1956.19±219.60 vs 1340.27±108.52 ng/L,P0.05),and CTL activity(47.91%±15.09% vs 31.82%±10.12%,P0.05).Also,the combined immunization elevated the proliferation rate of T lymphocytes more significantly than HV- peDNA3.1 vaccine alone(2.75%±0.26% vs 1.18%±0.06%,P0.05).The serum levels of specific IL-2 were 1246.84±157.02 ng/L and 1421.16±220.98 ng/L in mice immunized by HV-pcDNA3.1 alone and those by IL-2-pcDNA3.1 and HV-pcDNA3.1,respectively,but no statistical difference was found between them.Conclusion IL-2 eDNA may enhance the celluar immune response induced by HSV-2 multi-epitope DNA vaccine in mice.