Survival of immunized mice after a lethal tachyzoite challenge. Groups of mice were peritoneally immunized with one dose of PLG-rSAG1/2 MPs (●), one dose of rSAG1/2 (Vet L-10) (◆), two doses of rSAG1/2 (Vet L-10) (■), one dose of rSAG1/2 alone (○), one dose of blank PLG (◇), or one dose of PBS (□). Twelve weeks after immunization, six groups of 20 mice each were subcutaneously infected with 1 × 10⁴ live tachyzoites of T. gondii (RH strain). Animals were observed daily for 28 days and the final survival rates were calculated. All groups were analyzed by the chi-square test. An asterisk (*) indicates P < 0.05 when comparing the PLG-rSAG1/2 (single I.P. dose) group to the rSAG1/2 (Vet L-10) (single I.P. dose) group. Two asterisks (**) indicate P < 0.05 when comparing the PLG-rSAG1/2 (single I.P. dose) group to the rSAG1/2 (Vet L-10) (two I.P. doses) group.