A recombinant protein vaccine encoding Toxoplasma gondii Cyst wall 2 (dense granule protein 47) provides partial protection against acute and chronic T. gondii infection in BALB/c mice

Abstract

Toxoplasma gondii poses a major threat to economies and public health, and there are still no available vaccines for human against T. gondii infection. T. gondii cyst wall 2 (TgCST2, also known as dense granule protein-47) is a critical molecule in the establishment of chronic infection, making it a potential vaccine candidate. In this research, the recombinant TgCST2 (rTgCST2) was employed to evaluate the protective efficacy of TgCST2 antigen using BALB/c mice model against T. gondii infections via active immunization trials. First, the strong immunogenicity of TgCST2 was indicated by immunoblotting and immunofluorescence, which mean that TgCST2 might elicit robust immune responses in the organism. Then, after triply subcutaneous immunization with rTgCST2/ISA 201 emulsion, high levels of Toxoplasma-specific IgG, IgG1, IgG2a and cytokines (Interferon γ and interleukin 10) further suggested that TgCST2 was a promising immunogenic antigen. More importantly, this antigen could prolong survival in RH strain infected mice and resulted in the lower brain cysts size and number of PRU strain infected mice. These preliminary results demonstrated the immunoprophylactic effects of TgCST2 antigen and will inform new studies in developing subunit recombinant vaccines against T. gondii.