Induction of protective immunity by DNA vaccination with Toxoplasma gondii HSP70, HSP30 and SAG1 genes.

The vaccination with Toxoplasma gondii heat shock protein 70 (T.g.HSP70) gene (a virulent tachyzoite-specific) induced the most prominent reduction in T. gondii loads in various organs of B6 and BALB/c mice at the acute and chronic phases of toxoplasmosis compared with T.g.HSP30 (a bradyzoite-specific) and SAG1 (a tachyzoite-specific) genes. A single gene gun vaccination with 2 microg of T.g.HSP70 gene induced a significant reduction in the number of T. gondii organisms compared with 50 microg of T.g.HSP70 gene vaccination by intramuscular (i.m.) or intraperitoneal (i.p.) injection. The vaccine effects of T.g.HSP70 gene persisted for more than 3 months.