Construction of Hepatitis B Virus DNA Vaccine Carrying Interleukin-2 Gene

Objective To construct the hepatitis B virus(HBV) DNA vaccine carrying interleukin-2(IL-2) gene and explore its immune effect.Methods Insert internal ribosomal entry site(IRES) gene into the polyclonal site of plasmid pVAX1,then insert HBsAg and IL-2 genes into the same plasmid,at the two sides of IRES gene respectively,to construct HBV DNA vaccine pHII.Transfect COS-7 cells with pHII for transient expression.Immunize BALB/c mice with the extracted plasmid pHII for 3 times at weeks 0,2 and 4 respectively and determine the HBsAg and HBsAb contents in sera starting from week 1,using plasmid pVAX1 as negative control and plasmid pVAX/HBsAg as positive control.Kill the mice at week 13 and determine for the CD4+ and CD8+ on surface of T lymphocyte in murine spleens by flow cytometry.Results HBsAg and IL-2 were detected in the supernatant of COS-7 cells transfected with plasmid pHII.HBsAbs were detected in the sera of mice in test and positive control groups at weeks 2 and 4 respectively,but not detected in those of mice in negative control group.However,no HBsAg was detected in the three groups.Compared with those in positive control group,the antibody in test group appeared 2 weeks earlier,the antibody positive rate was 2.5 times higher,and the quantity of antibody increased about 3 folds.Both the number of CD4+ molecule and the ratio of CD4+ to CD8+ of mice in test group were significantly higher than those in positive control group.Conclusion The constructed HBV DNA vaccine pHII induced immune response in mice successfully.Compared with that of HBV DNA vaccine without molecular adjuvant,the immune effect of the constructed HBV DNA vaccine was good.