[Dynamic changes of immune responses in BALB/c mice immunized with a recombinant Bb(pGEX-Sj14-3-3) vaccine of Schistosoma japonicum].

OBJECTIVE

To investigate the dynamic changes of the immune responses in mice immunized with a recombinant (Bifidobacterium bifidum, Bb) (pGEX-Sj14-3-3) vaccine of Schistosoma japonicum.

METHODS

BALB/c mice were immunized orally or intranasally by the vaccine. At the interval of every two weeks up to the 22nd week of post-vaccination, the levels of serum IgG, IgG subclass, IgE and IgA were determined by ELISA. Proliferation of splenocytes was observed with MTT assay. The percentage of T-lymphocyte subsets and the rate of apoptotic splenocytes were determined by flow cytometry. The production of IFN-γ, IL-12, TNF-α and IL-10 were quantified by ABC-ELISA in the supernatant of cultured splenocytes.

RESULTS

The orally immunized mice achieved the peaks of IgG, IgG1, IgG2a, IgG2b, IgG3, IgE and IgA at 8, 6, 6, 4, 8, 10 and 6 weeks, respectively. The proliferation and the apoptosis rates of splenocytes came to peaks at 4 week, so did the intranasally immunized group. The percentages of CD4(+);T cells and CD8(+);T cells peaked at 8 and 14 weeks, respectively. IFN-γ, IL-12, TNF-α and IL-10 reached the highest levels at 8, 8, 6 and 4 weeks, respectively. The intranasally immunized group reached to the peaks of IgG, IgG1, IgG2a, IgG2b, IgG3, IgE and IgA at 4, 6, 4, 4, 8, 10 and 8 weeks, respectively. The proportion of CD4(+);T cells peaked at 8 weeks, while CD8(+);T cells at 4 weeks. IFN-γ, IL-12, TNF-α and IL-10 achieved the highest values respectively at 2, 2, 4 and 4 weeks.

CONCLUSION

The recombinant Bb(pGEX-Sj14-3-3) vaccine could induce effective immune responses in mice by either oral vaccination or intranasal inoculation. The better immunogenicity of intranasal vaccination is proved.