Intranasal Immunization With STAg Plus CpG ODN And CT Induces Toxoplasma Gondii Specific Immune Responses

Objective This study was performed to determine the optimal dose of CpG ODN acted as mucosal adjuvant of STAg, observe the persistent time of immune response after intranasally immunizied mice with optimal dose CpG ODN plus STAg and investigate the synergistic effect of CpG ODN and CT. The aim of this study was providing the theory and experimental evidence for developmenting the complex mucosal vaccine of Toxoplasma gondii.Method First part: Fifty 5-to 6-week-old BALB/c mice were randomly divided into five groups. The mice of experimental groups were immunized intranasally two times at 14-day intervals with 20μg STAg plus 0μg, 1μg, 5μg or 10μg CpG ODN, respectively. The mice of control group were immunized intranasally with PBS at the same time. All animals were killed on day 30 after the last immunization. Lymphocytes of spleen, Peyer's patch, mesenteric lymphocyte code (MLN) and intraepithelial lymphocyte (IEL) were counted. The content of IgA antibody in the feces and IgG in the sera were detected by ELISA.Second part: 5-to 6-week-old female BALB/c mice were divided into control group and infected group. Each group had 36 mice. The mice of experimental groups were immunized intranasally two times at 14-day intervals with 10μg CpG ODN plus 20μg STAg. The mice of control group were immunized intranasally with PBS at the same time. Six mice in each group were killed per time-point on week 1, 2, 3, 4, 5, 6 respectively. After last immunity, IgA in rinse solution of intestimal, nasopharynx, lung and vaginal and IgG in the sera were detected by ELISA. Lymphocytes of spleen and intraepithelial lymphocyte (IEL) were counted.Third part: Thirty 5-to 6-week-old BALB/c mice were randomly divided into four experimental groups and one control group. The mice of experimental groups were immunized intranasally two times at 14-day intervals with 20μg STAg, 20μg STAg plus 10μg CpG ODN, 20μg STAg plus 1μgCT and 20μg STAg plus 10μg CpG ODN /1μgCT, respectively. The mice of control group were immunized intranasally with PBS at the same time. All animals were killed on day 20 after the last immunization. The content of IgA antibody in rinse solution of intestinal tract and IgG in the sera were detected by ELISA. MTT assay tested the proliferate reaction of splenic lymphocyte in vitro.Results Proliferative responses were observed in gut-associated lymphoid tissue and spleen lymphocytes in the 10μg CpG ODN group, and higher than the control...