Survival of immunized mice after a lethal tachyzoite challenge. Groups of mice were intraperitoneally immunized twice with PLG-rSAG1 microparticles (■ ), rSAG1 (Vet L-10) (● ), soluble rSAG1 alone (□ ), PLG (◊ ), or PBS (○ ). Eight weeks after boosting, five groups of 10 mice each were subcutaneously infected with 1×104 live tachyzoites of T. gondii (RH strain). Animals were observed daily for an additional month (28 days) and the final survival rates were calculated. *P<0.05 when comparing the PLG-rSAG1 group to the rSAG1 (Vet L-10) group.