Studies Of Immunoportection And Its Mechanism Of Recombinant Myophilin Against Echinococcus Granulosus In Mice

Object: To identify vaccine candidate character of recombinant myophilin against hydatidosis,through detecting the immunoprotection and its mechanism. Methods: (1) We expressed and purify the protein from recombinant engineering bacteria rEg.myophlilin/pET-28a, and then identified its immuno-character. (2) We preparated the vaccine by emulsifying rEg.myophilin with complete/ imcomplete Freund's adjuvant for immunization or booster. (3) Three groups of female mice were used, and grouped them as A, B, and C, which were immunized subcutaneously with phosphate buffered saline (PBS), Freund's complete adjuvant (FCA) in PBS or rEg.myophilin with FCA respectively. Two weeks after additional two boosters, mice were challenged with 1500 Eg protoscoleces (PSCs) intraperitoneally. (4) immunoprotection was computed by formula: reduction in cyst load = 1-(average of cysts in test group / average of cysts in control group)×100%. Serum and spleens were collected at different time point by sacrificing 5 mice in each group. Antibodies in serum and cytokines in supernatant of lymphocytes cultures were measured. Result: mice immunized with rEg.myophilin produced effective immunity protection (reductions in cyst load are 89.86% and 86.11% compared with group A and B). Compared to control groups, mice immunized with rEg.myophilin showed that specific IgG, IgG1, IgG2a and IgE accompanied by IFN-γand IL-4 significantly increased after one or more times of immunization, but neither IgG2b nor IgG3 increased. Nevertheless, IL-10 significantly increased in the control groups compared with rEg.myophilin group in which it appeared a decline trend. Conclusion: rEg.myophilin was identified as a vaccine candidate for its effective protection (reduction in cyst load >86.11%), rEg.myophilin showed a effectively protective immunity, which may attribute to: (1) IgGs and IgE-mediated humoral immune response, (2) cell-mediated immunity (especially Th1 cell marked by IFN-γ)was associated with this high immunoprotection. (2) Humoral immune and cytoimmunity complement and influence each other, IL-4 assists to stimulate type transformation of IgE which plays an important role in Eosinophils-related anti-parasite immunity.