Evaluation Of Immunogenicity Of Recombinant SAG1 DNA Vaccine Based On Five Different Molecular Adjuvants

The purpose of this experiment was to investigate the adjuvant effects of the molecular adjuvants EDA,FliC,TAT,OvASP1 and Calreticulin(Cal)on the immune predominant antigen SAG1 of Toxoplasma gondii.Firstly molecular adjuvants EDA,FliC,TAT,OvASP1,and Calreticulin and SAG1 were coloned and ligated into the the eukaryotic expression recombinant plasmid pVAX1 to yield to the following plasmids:pVAX1-SAG1,pVAX1-EDA-SAG1,pVAX1-FliC-SAG1,pVAX1-TAT-SAG1,pVAX1-OvASP1-SAG1,pVAX1-Cal-SAGl.Secondly,the constructed expression vectors were confirmed by double enzymes digestion and sequencing,after the identification,large number of recombinant plasmids were extracted for immunization.The levels of antibodies IgG,IgG2a,and IgGl in the serum of mice were measured after the third immunizations,and the concentration of cytokines IL-4,IL-10,IL-12p70,IFN-γ and lymphocytes proliferation were also evaluated.Finally,the immunized mice were challenged with Toxoplasma gondii RH strain.The immunoprotective effect of the recombinant vaccines were studied by recording the survival times of the mice.The results obtained in this experiment are as follows:The level of antibodies IgG,IgG2a,IgG1 were significantly higher in the molecular adjuvant groups than that in the control groups.Among them,the levels of antibodies produced by the molecular adjuvants EDA-SAG1 group and Cal-SAG1 group were higher than other adjuvants groups.The level of cytokines IL-4,IL-10,IL-12p70,and IFN-y in the molecular adjuvants EDA-SAG1 group and Cal-SAG1 group were significantly higher compared with other groups.The molecular adjuvant EDA-SAG1 group had the higher cell proliferation rates than other groups.After the mice were infected with Toxoplasma gondii RH strain,the survival times of the molecular adjuvant Cal-SAG1 group and EDA-SAG1 group were the longest,and they survived for 5 days more than the blank control group.CONCLUSION:The molecular adjuvants EDA and Cal can significantly enhance the immune response of the recombinant DNA vaccine against Toxoplasma gondii,and can also improve the immunoprotective effect of the Toxoplasma gondii DNA vaccine.