Intranasal Immunization With STAg And IFN-γ Adjuvant Induces Toxoplasma Gondii Specific Mucosal And Systemic Immune Responses

ObjectiveThis study was performed to investigate the mucosal and systemic immune responses after intranasal immunization with STAg plus IFN-γadjuvant and the effects on protection of mice against Toxoplasma gondii.MethodsThis study included three parts. The first part was to investigate the effects of IFN-γintranasally administrated on protection of mice against Toxoplasma gondii. Forty-five 5-to 6-week-old BALB/c mice were randomly divided into three groups, fifteen mice of each group were administrated intranasally with IFN-γbefore or after infection with Toxoplasma gondii tachyzoites. Control mice were administrated with water for injection before infection. The condition of mice infected about health and death were observed. Mice were killed on day 30 after infection, the tachyzoites of their livers, spleens and brains were counted.The second part was to observe the protective role of IFN-γintranasally administrated against Toxoplasma gondii infection and the immune effect. Forty-five 5- to 6-week-old female BALB/c mice were randomly divided into three groups, fifteen mice of each group were immunized intranasally two times at 14-day intervals with 20μg STAg alone, 20μgSTAg plus 1000UIFN-γ, while mice intranasally administrated with PBS in the same means were control. The PBS containing 4×104 tachyzoites of RH strain in each 0.5-ml volume were orally administered to all animals on day 10 after the last immunization. The weight and survival of mice were recorded day by day. Survivors were killed on day 43 after infection, the tachyzoites of brains and livers were counted, the number of T lymphocytes in IEL,Payer's patches and spleen were determined, the CD4+ and CD8+ T lymphocytes of which were determined by immunohistochemistry (SABC), the content of IgA antibody in the feces, nasopharynx wash, lung wash, vaginal wash, sera and IgG in the sera were detected by ELISA.The third part was performed to study the mucosal and systemic immunity responses after intranasal immunization with STAg and IFN-γadjuvant. We observed the responses in NALT, GALT and systemic immunity, and the duration of the responses. BALB/c mice were randomly divided into two groups immunized group and control one, 42 mice per group. Mice were intranasally immunized with 20ug STAg and 1000U IFN-γpermouse at internal of two weeks, while control mice were given PBS solution instead. Twelve mice of each group were killed respectively before immunization and on week 2 after the first immunization and on week 2, 4, 6, 8,10 after the intensified immunization.The IgG and IgA in serum, nasopharynx, lung and intestine washes were detected by ELISA.The thymus and spleen was weighed and the number of the peyer's patches was counted. Lymphocytes in spleen and IEL were isolated and counted.