Immunization of mice with egG1Y162-1/2 provides protection against Echinococcus granulosus infection in BALB/c mice

This study is to predict and purify the T-B combined epitopes of egG1Y162 antigen in Echinococcus granulosus, and to evaluate their immunogenicity in mice.

The bioinformatics software was used to predict the T-B combined epitopes of egG1Y162 antigen. Recombinant egG1Y161/2 peptides were constructed, expressed and purified. Mice were immunized with egG1Y161/2 peptides. The serum and spleen cells were isolated. The isolated spleen cells were stimulated with egG1Y161/2 peptides in vitro and the culture supernatant was collected. The levels of IgG in serum and levels of IL-4 and IFN-γ in the culture supernatant were measured by ELISA. The weight and number of the fresh hydatid cysts were evaluated. The serum ptotoscolicidal activity was measured by the complement dependent cytotoxicity assay.

Peptides of 6-19aa, 64-82aa, 106-119aa were predicted as T-B combined epitopes of egG1Y162 antigen. And, recombinant protein egG1Y162-1 or egG1Y162-2, which contained T-B combined epitope(s) of the 6-19aa, or the 64-82aa and the 106-119aa in egG1Y162 antigen, respectively, was successfully expressed and purified. Serum IgG levels of mice immunized with egG1Y162-1/2 were significantly increased during the immune response to Echinococcus granulosus. The levels of IFN-γ, IL-4 and the ratio of IFN-γ/IL-4 after egG1Y162-1/2 immunization were significantly higher. Weight and number of the fresh hydatid cysts in egG1Y162-1/2 immunized mice was significantly decreased. And, the serum protoscolicidal activity after egG1Y162-1/2 immunization was enhanced.

The egG1Y162-1/2 induces production of serum IgG levels and Th1 cell immune response, which enhances the protective immunity in Echinococcus granulosus challenged mice and thus may be used as a potential vaccine candidate.