Evaluation of the toxoplasma Urm1 gene deletion mutant (PruΔUrm1) as a promising vaccine candidate against toxoplasmosis in mice

Toxoplasmosis is a significant zoonotic disease that poses a serious threat to both human and animal health. Despite ongoing research, developing an effective vaccine for toxoplasmosis remains a challenge. In this study, we evaluated the vaccine potential of the Toxoplasma Urm1 gene deletion mutant (PruΔUrm1) by assessing its pathogenicity and protective efficacy in mice. Using CRISPR/Cas9 technology, we successfully created a type II Toxoplasma gondii Pru mutant strain with a deleted Urm1 gene. Compared to the wild-type parasite, the PruΔUrm1 strain exhibited significantly reduced invasive and proliferative abilities in vitro. In in vivo studies, mice intraperitoneally infected with the parental Pru strain showed severe symptoms including emaciation, hunching, and high mortality rates. In contrast, mice infected with PruΔUrm1 tachyzoites demonstrated a 100 % survival rate, no overt symptoms, and a markedly reduced parasite burden in the liver, spleen, and lungs, indicating reduced pathogenicity. Notably, PruΔUrm1 vaccination triggered a strong immune response, characterized by significantly elevated cytokine levels, including TNF-α, IFN-γ and IL-10. Furthermore, we assessed the immunoprotective efficacy of PruΔUrm1 vaccination in mice against type I strains. Mice immunized with PruΔUrm1 were able to resist the tachyzoites of type I RH wild-type parasites, achieving a 100 % survival rate and significantly reduced parasite loads in the liver, spleen and lungs. These data demonstrate that PruΔUrm1 immunization provides effective protection against acute Toxoplasma infections and holds promise as a potential vaccine candidate for toxoplasmosis.