The protective effect of a DNA vaccine encoding the Toxoplasma gondii cyclophilin gene in BALB/c mice

Toxoplasmosis is a world-wide zoonosis that causes significant public health and veterinary problems. The study of vaccines remains the most promising method for the future prevention and control of toxoplasmosis. Recombinant Toxoplasma gondii cyclophilin has been shown to have potent PPIase and IL-12-inducing activities, thus promoting the stabilization of T. gondii's life cycle and maintaining the survival of its host during evolution. In this study, the T. gondii cyclophilin gene was used to construct a DNA vaccine (pVAX1-TgCyP). The immune response and protective efficacy of the vaccine against T. gondii infection in BALB/c mice were evaluated. All BALB/c mice that were vaccinated with pVAX1-TgCyP developed a high response with TgCyP-specific antibodies, and significant splenocyte proliferation (P < 0·05) compared with pVAX1 vector and PBS groups. pVAX1-TgCyP also induced a significant Th1 type immune response, indicated by the higher production of IL-2 and IFN-γ (P < 0·05). The survival rate of BALB/c mice increased significantly after vaccination with pVAX1-TgCyP (37·5%) (P < 0·05). These results indicate that TgCyP is a highly efficacious vaccine candidate that can generate protective immunity against T. gondii infection in BALB/c mice.