Toxoplasma gondii, a specialized intracellular parasite, causes a widespread
zoonotic disease and is a severe threat to social and economic development. There is a lack of effective drugs and
vaccines against T. gondii
infection. Recently,
mRNA vaccines have been rapidly developed, and their packaging materials and technologies are well established. In this study, TGGT1_216200 (TG_200), a novel molecule from T. gondii, was identified using bioinformatic screening analysis. TG_200 was purified and encapsulated with a
lipid nanoparticle (LNP) to produce the TG_200
mRNA-LNP
vaccine. The immune protection provided by the new
vaccine and its mechanisms after immunizing BABL/C mice via
intramuscular injection were investigated. There was a strong immune response when mice were vaccinated with TG_200
mRNA-LNP. Elevated levels of
anti-T. gondii-specific
immunoglobulin G (
IgG), and a higher IgG2a-to-IgG1 ratio was observed. The levels of
interleukin-12 (IL-12),
interferon-γ (IFN-γ),
IL-4, and
IL-10 were also elevated. The result showed that the
vaccine induced a mixture of Th1 and Th2 cells, and Th1-dominated humoral immune response. Significantly increased
antigen-specific splenocyte proliferation was induced by TG_200
mRNA-LNP immunization. The
vaccine could also induce T. gondii-specific cytotoxic T lymphocytes (CTLs). The expression levels of
interferon regulatory factor 8 (IRF8), T-Box 21 (T-bet), and
nuclear factor kappa B (NF-κB) were significantly elevated after TG_200
mRNA-LNP immunization. The levels of CD83, CD86, MHC-I, MHC-II, CD8, and CD4 molecules were also higher. The results indicated that TG_200
mRNA-LNP produced specific cellular and humoral immune responses. Most importantly, TG_200
mRNA-LNP immunized mice survived significantly longer (19.27 ± 3.438 days) than the control mice, which died within eight days after T. gondii challenge (P< 0.001). The protective effect of adoptive transfer was also assessed, and mice receiving serum and splenocytes from mice immunized with TG_200
mRNA-LNP showed improved survival rates of 9.70 ± 1.64 days and, 13.40 ± 2.32 days, respectively (P< 0.001). The results suggested that TG_200
mRNA-LNP is a safe and promising
vaccine against T. gondii
infection.