Intranasal Immunization With ESA And STAg Induces Toxoplasma Gondii Specific Mucosal And Systemic Immune Responses In Mice

Objective To identify candidate of complex antigens of Toxoplasma gondii, we observed that excreted-secreted antigens (ESA) and/or soluble tachyzoite antigen (STAg) administrated intranasally induced mucosal and systemic immune response in mice.Methods This study included three parts. In first part, to determine the optimal phrase of ESA, we observed that different-phrase ESA administrated intranasally induced mucosal and systemic immune responses in mice. Eight BALB/c mice were twice intranasally immunized with 20μg different-phrase ESA per mouse at an internal of 14 days, respectively, which were taken from the infected mice peritoneal fluids on 0h, 6h, 12h, 24h, 36h, 48h and 60h after Toxoplasma gondii infection, while mice in the control group were immunized with 20μl PBS per mouse. The healthy condition of mice was observed and the body weight (BW) of mice was recorded everyday. On day 14 after the last immunization, IgG in serum and sIgA in intestinal washes were detected by ELISA. Intestinal intraepithelial lymphocytes (iIEL), mesenteric lymph node lymphocytes (MLNL) and spleen lymphocytes were isolated and counted.In second part, to determine the optimal dosage of ESA, we observed that different-dosage ESA administrated intranasally induced mucosal and systemic immune responses in mice. Eight BALB/c mice were twice immunized intranasally with 5μg ESA, 10μg ESA, 20μg ESA and 30μg ESA per mouse at interval of 14 days, respectively, while mice in the control group were immunized with 20μl PBS per mouse. The healthy condition of mice was observed. On day 14 after the last immunization, sIgA in nasopharyngeal and intestinal washes and IgG in serum were detected by ELISA, meanwhile iIEL, MLNL and spleen lymphocytes were isolated and counted.In third part, to determine the effect of complex antigens, we observed that ESA and/or STAg administrated by intranasal route, respectively, induced mucosal and systemic immune responses in mice. Ten BALB/c mice were twice immunized intranasally with 30μgESA, 20μgSTAg and 25μg combination of 15μg ESA and 10μg STAg per mouse at an internal of 14 days, respectively, while mice in the control group were immunized with 20μl PBS per mouse. The healthy condition of mice was observed and the body weight (BW) of mice was recorded everyday. On day 14 after the last immunization, IgG in serum and sIgA in intestinal washes were detected by ELISA. iIEL and spleen lymphocytes were isolated and counted.Results Besides 60h group, mice in all other groups were healthy, BW remained increase with time chang after intranasal immunization with different-phrase ESA. In 60h group, the condition of mice was not good, and the increase of BW was slower than all other groups (P<0.05). In experimental groups, the level of specific antibodies in serum and mucosal site were rising;...