Observation on immunogenicity of Toxoplasma gondii excreted/secreted antigen and soluble tachyzoite antigen

Objective To study the immunogenicity of Toxoplasma gondii excreted/secreted antigens (ESA) and soluble tachyzoite antigen (STAg) after intranasal immunization. Methods BALB/c mice were randomly divided into 3 groups, 10 mice each group. Mice were intranasally immunized with 20 μl PBS per mouse and 20 μg ESA or STAg per mouse, respectively, twice at an internal of 2 weeks. Ten mice of each group were killed on day 14 after the last immunization. Spleen lymphocytes and intestinal intraepithelial lymphocytes (iIEL) were counted. Serum IgG and IgA in intestinal washes were detected by ELISA. Results Cell proliferation of spleen lymphocytes and iIEL was observed in all antigen groups on day 14 after the last immunization, and compared with the PBS group, there was a significant difference ( P ＜0.05). The level of serum IgG in all antigen groups was higher than that in PBS group on day 14 after immunization with a significant difference ( P ＜0.01 ). On day 14 after immunization, the level of IgA in ESA group and STAg group was higher than that in PBS group (P ＜ 0.01 ). Conclusion Intranasal immunized with ESA or STAg can effectively induce the mucosal and systemic immune responses with potent immunogenicity. Key words: Toxoplasma gondii; Excreted/secreted antigen; Soluble tachyzoite antigen; Intranasal immunization; Immunogenicity