Protection of BALB/c mice against Toxoplasma infection. Six-week-old mice (20/group) were intranasally immunised on days 0, 14, 21 with 30 μg of rTgPGAM 2 or PBS as a control. (A) Two weeks after the last booster, the mice were challenged by gavage with 1 × 10⁴ tachyzoites of the T. gondii RH strain. Thirty days after the challenge, brain and liver tachyzoites were enumerated using q-PCR assay. The results are expressed as the mean ± SD (n = 8) and represent the numbers of tachyzoites in 1 g of tissue. **P < 0.01 (vaccinated vs. PBS group). (B) Two weeks after the last booster, the mice (12/group) were challenged with 4 × 10⁴ tachyzoites of T. gondii via the oral route. Survival was monitored and recorded daily for 30 days after challenge. Control mice immunised with PBS died within 11 days, and the mice immunised with rTgPGAM 2 died from days 9 to 17.