Protective Effect Of A Multiantigenic DNA Vaccine Against Toxoplasma Gondii With Co-delivery Of Interleukin-12 In BALB/c Mice

The protozoan parasite Toxoplasma gondii invades and replicates within nucleated cells of warm-blooded animals and causes toxoplasmosis. To control T. gondii, a tool such as a vaccine is necessary because of the massive disease burden of T. gondii in the world. In the present study, we contructed a multiantigenic DNA vaccine, pSAG1-ROP2-SAG2 (SAG1 being expressed only by tachyzoites and ROP2 being expressed by tachyzoites, bradyzoites and sporozoites, and SAG2 being expressed by tachyzoites), and examined the expression ability of the DNA vaccine in Hela cells. Afterwards, we tested the effect of the multi-component vaccine with or without pIL-12 as an adjuvant in BALB/c mice. After T. gondii RH strain challenge, mice immunized with pcDNA3.1-SAG1-ROP2-SAG2 displayed significant high survival rates. Moreover, the protection was markedly enhanced by pIL-12 co-administration.The results show that that immune response elicited by pSAGl-ROP2-SAG2 vaccination was stronger than those by pSAG1-ROP2, pSAG2, expression vector alone, or PBS. Our study demonstrated that multiantigenic DNA vaccine expressing SAG1, ROP2 and SAG2 is more potent than single gene vaccine and double gene vaccine. Simultaneous murine IL-12 expression plasmid vaccination could enhance the potency of a multiantigenic DNA vaccine.