Deletion of Rhoptry Protein 38 (PruΔ) as a Vaccine Candidate for Toxoplasmosis in a Murine Model.

Toxoplasmosis is a serious zoonotic disease that threatens human and animal health. Here, we evaluated the vaccine potential of the deletion of rhoptry protein 38 (PruΔ) through its pathogenicity and immunoprotective efficacy in mice. Mice inoculated intraperitoneally with 1 × 10, 2 × 10, or 4 × 10 PruΔ showed no visible signs, whereas mice inoculated with 1 × 10 parental Pru strain showed obvious wasting and bow-back, suggesting a significantly lower pathogenicity of PruΔ in mice. Vaccination with 1 × 10 PruΔ triggered a mixed Th1/Th2 response (Th1 response predominant), with higher IgG, IgG2a, and IgG1 levels in serum from week 3 to week 12, and a significant increase in IFN-γ, IL-12, and IL-10 in suspensions of splenocytes at 30 or 60 days post-immunization. All vaccinated mice survived when infected intraperitoneally with tachyzoites (RH, Pru, VEG, or TgcatBJ1) or when infected orally with cysts (Pru or ME49). The brain parasite burden during Pru tachyzoite, Pru cyst and ME49 cyst challenges were significantly reduced in vaccinated mice. The duration of immunization showed that vaccination with PruΔ could protect mice from challenge with different varied genotypes of strains against different routes of infection. Collectively, these findings indicate that PruΔ is an attenuated strain that provides long-term protective efficacy against acute or chronic toxoplasmosis in mice.