| Summary: | <i>Toxoplasma gondii</i> is a protozoan parasite, occurring worldwide, endangers human health and causes enormous economic losses to the Ministry of Agriculture. A safe and effective vaccination is needed to handle these problems. In addition, ideal vaccine production is a challenge in the future. In this study, we knocked out the adenylosuccinate lyase (<i>ADSL</i>) gene and found that the gene reduces the growth rate of <i>T. gondii</i> tachyzoites in vitro under standard growth conditions by plaque or replication experiments. Furthermore, mice that were immunized with tachyzoites of the ME49Δ<i>ADSL</i> strain induced 100% protection efficacy against challenge with the type 1 strain RH, type 2 strain ME49 and type 3 strain VEG. All mice that were immunized with ME49Δ<i>ADSL</i> had a survival rate of 100% when they were reinfected with wild-type strains, either 30 days or 70 days after immunization, and immunization was also protective against homologous infection with 50 <i>T. gondii</i> ME49 tissue cysts. In addition, the level of <i>Toxoplasma</i>-specific IgG was significantly elevated at 30 and 70 days after immunization. ME49Δ<i>ADSL</i> induced high levels of Th1 cytokines (interferon gamma (IFN-γ), interleukin (IL)-12) at 4 weeks after immunization and spleen cell cultures from mice vaccinated for 150 days were able to produce robust INF-γ and IL-12 levels in the supernatant. The results of the present study showed that Δ<i>ADSL</i> vaccination induced a T. <i>gondii</i>-specific cellular immune response against further infections. These results suggest that the ADSL-deficient vaccine can induce anti-<i>Toxoplasma gondii</i> humoral and cellular immune responses and has 100% immune protection against post-challenge by the type 1 strain RH, type 2 strain ME49 and type 3 strain VEG. It will be used as an excellent candidate for live vaccines and may contribute in a positive meaning to control human toxoplasmosis.
|
|---|