Synthetic rEg.P29 Peptides Induce Protective Immune Responses Against Echinococcus granulosus in Mice.

Background:Echinococcus granulosus represents a significant threat to animal husbandry and human health, but its consequences are often underestimated. Vaccination can prevent E. granulosus infection. We investigated the immune protective effect induced by the recombinant protein P29 of E. granulosus (rEg.P29) peptide vaccine. Methods: The CD4(+) T-, CD8(+) T-, Treg-, and CD8(+)CD107a(+) T-cell proportions in the spleen and peripheral blood of infected mice were analyzed using flow cytometry. Additionally, we measured the proportions of IFN-γ and IL-2 secreted by memory T cells, CD19(+)CD138(-)B cells, CD19(+)CD138(+) plasmablasts, CD19(-)CD138(+) plasma cells, and CD19(+)IgD(-)IgG(+) and CD19(+)IgD(-)IgA(+) memory B cells. Results: No significant differences were noted in CD4(+) T-, CD8(+) T-, and CD8(+)CD107a(+) Treg-cell percentages among the experimental groups. However, IFN-γ, IL-2, and TNF-α levels and vaccine-specific antibody concentrations in the plasma were significantly elevated in the rEg.P29(T+B) + CpG + infection and rEg.P29 + CpG + infection groups compared to those in the PBS + infection and CpG + infection groups. Similarly, CD19(-)CD138(+) plasma cell and CD19(+)IgD(-)IgG(+) and CD19(+)IgD(-)IgA(+) memory B-cell populations, along with specific antibodies, were significantly higher in these groups. Especially, the average cyst burden in the rEg.P29(T+B) + CpG + infection and rEg.P29 + CpG + infection groups was significantly reduced compared to that in the PBS + infection and CpG + infection groups. Conclusions: Synthetic peptide vaccines targeting rEg.P29 can effectively inhibit cysts, offering a novel strategy for the development of vaccines against E. granulosus. These findings provide a foundation for further research on the immunogenicity and protective efficacy of rEg.P29-based vaccines.