Abstract
Cystic echinococcosis (CE) is a zoonotic disease caused by the infection of Echinococcus granulosus (E. granulosus) larva. Currently, blocking the pathogenic cycle chain through immunoprophylaxis has become the main research direction. EgG1Y162 protein has good antigenicity and immunogenicity and is therefore a good candidate molecule for E. granulosus vaccine. Mature T cells express CTLA-4 on their surface, and its extracellular IgV region binds efficiently to the B7 molecules on antigen-presenting cells to deliver negative signals. We designed and prepared a recombinant vaccine by fusing CTLA-4IgV to the EgG1Y162 protein to exploit its binding properties. Bioinformatic methods were used to analyze the structure and epitopes of the proposed recombinant vaccine. The placement of 16 amino acids (GTDDDDKAMADIGSEF) between the CTLA-4IgV and EgG1Y162 using the skeleton structure of pET30a plasmid did not affect the correct folding of the proteins. When the recombinant proteins were co-cultured with bone marrow-induced dendritic cells (DC), the protein CTLA-4IgV-EgG1Y162 promoted its binding to DC and increased the percentage of DC maturation compared with protein EgG1Y162 in vitro and in vivo. Compared to EgG1Y162, CTLA-4IgV-EgG1Y162 promoted the proliferation of lymphocytes in spleen and the release of interferon (IFN)-γ and interleukin (IL)-4 by those lymphocytes in vitro, while it also promoted the release of protective antibodies in the serum of immunized mice in vivo. These findings indicated that the designed recombinant vaccine, CTLA-4IgV-EgG1Y162, can provide new ideas for the optimization and improvement of vaccines against E. granulosus.