Coexpression of interleukin-2 enhances the immunization effect of a DNA vaccine expressing herpes simplex 1 glycoprotein D.

In this study, DNA vaccines consisting of vector IRES-gD expressing Herpes simplex virus 1 (HSV-1) glycoprotein D (gD) and vector IRES-gD-IL-2 coexpressing HSV-1 gD and interleukin-2 (IL-2), respectively, were constructed. After intramuscular inoculation, both vaccines induced in BALB/c mice antibodies as assayed by ELISA and virus neutralization. However, IRES-gD-IL-2 elicited significantly higher levels of IgG (ELISA) and neutralizing antibodies than IRES-gD. Isotyping of sera from mice injected with IRES-gD-IL-2 revealed predominantly IgG2a antibodies. IRES-gD-IL-2 also elicited a higher delayed-type sensitivity (DTH) reaction. However, there was no difference in the protection against lethal challenge with HSV-1 between the two vaccines (P>0.05). The results suggest that the vaccination with IRES-gD-IL-2 can efficiently enhance the immune response of mice to HSV-1, particularly through increased cellular immunity.