Evaluation Of The Immune Response Induced By Multiantigenic DNA Vaccine Encoding SAG1 And ROP2 Of Toxoplasma Gondii And The Adjuvant Properties Of Cholera Toxin A2/B Subunits And Murine Interleukin-12 Plasmid In BALB/c Mice

The heavy incidence and severe or lethal damages of toxoplasmosis clearly indicate the need for development of the more effective vaccine. In the present study, we constructed a multiantigenic DNA vaccine, eukaryotic plasmid pcDNA3.1-SAG1-ROP2, expressing surface protein SAGl(main surface antigen 1) and ROP2 (rhoptry protein 2 ) of Toxoplasma gondii, and examined the expression ability of the DNA vaccine in Hela cells by Western blot. Afterwards, we investigated the efficacy of pcDNA3.1-SAG1-ROP2 with or without co-administration of a plasmid encoding cholera toxin A2/B subunits (pCTA2/B) or murine interleukin-12 (pIL-12) as genetic adjuvant to protect BALB/c mice against toxoplasmosis. After T. gondii RH strain challenge, mice immunized with pcDNA3.1-SAG1-ROP2 displayed significant high survival rates. Moreover, the protection was markedly enhanced by pIL-12 co-administration. The results show that mice immunized with pcDNA3.1-SAG1-R0P2 elicited stronger humoral immune responses than those immunized with single-gene plasmids, empty plasmid or PBS. Furthermore, co-immunization with IL—12 genes resulted in a dramatic enhancement of these responses. Our study indicates that the introduction of multiantigenic DNA vaccine is more powerful and efficient than single-gene vaccine, and the co-delivery of pIL-12 further enhanced the potency of multiantigenic DNA vaccine.