Protective effect of STAg through different immunization routes against Toxoplasma gondii infection in mice

Objective To investigate the protective effect of soluble tachyzoite antigen (STAB) against Toxoplasma gondii in mice after intranasal,intmgastric administration or subcutaneous injection with Toxoplasma gondii STAB.Methods Forty 6 to 7 weeks old BALB/cm icewere randomly divided into four groups.Them ice in intmnasal,intragastric administration and subcutaneous injection group were inm unized two times with 20μg STAg,at an interval of 2 weeks respectively and the control group was not immunized.On the day 14 after last immunization,all micewere challenged through intragastric administration with 2×10⁴ tachyzoites of RH strain The health of mice was observed day by day,recording the body weight and survival rate of the mice.The survivors were sacrificed on the day 30 after challenge; the tachyzoites in spleens and brains were counted.Results The health of mice in intranasal group was better than other groups,and the survival rate of intranasal group (70%)was higher than that of subcutaneous injection (60%),intmgastric administration (60%)and control group(40%).The tachyzoite loads in spleen in intmnasal(369.48) and subcutaneous injection(386.94) groups were significantly lower than that of intragastric administmtion group (630.40) and control group (664.93,F=3.611,P<0.05).The tachyzoite loads in brain in intranasal,intragastric adm inistmtion and subcutaneous injection groups had no difference,butwere signuficantly lower than that of control group (F=1.999,P<0.05).Conclusion Them ice immunized intmnally with 20μg STAB induced effective protection against Toxoplasma gondii,which outstripped that of intragastric administration and subcutaneous injection group.