• Vaccine Name: T. gondii Pru strain cdpk2 mutant vaccine
• Target Pathogen: Toxoplasma gondii
• Target Disease: Toxoplasmosis
• Type: Live, attenuated vaccine
• Status: Research
• Host Species for Licensed Use: Human
• Immunization Route: Intraperitoneal injection (i.p.)
• Description: T. gondii attenuated vaccine: used CRISPR-Cas9 method to delete cdpk2 gene in T. gondii Pru strain (Wang et al., 2018)

Mouse Response

• Host Strain: Kunming mice (Wang et al., 2018)
• Vaccination Protocol: Mice were either vaccinated once with 500 freshly harvested Pru:Δcdpk2 tachyzoites or mock-vaccinated in a total of 200 µL phosphate-buffered saline (PBS) ip. (Wang et al., 2018)
• Immune Response: Humoral: Higher levels of IgG and IgG2a antibodies 28 dpv, increased level of IgG1 at 70 dpv (Wang et al., 2018)
  Cellular: Significantly higher levels of Th1-type cytokines (IFN-γ, IL-2, and IL-12) and Th2-type cytokine (IL-10) at 70 dpv. (Wang et al., 2018)
• Challenge Protocol: At 70 dpv, both vaccinated and age-matched naive mice were challenged.
  Acute: mice were challenged ip with 200 μL PBS containing 1000 tachyzoites of RH, or ToxoDB#9 (PYS or TgC7) strain
  Chronic: mice were inoculated orally with 20 Pru cysts.
  Congenital: female mice were mated to males on a 2:1 ratio 70 days post vaccination. Compared between three groups: (A) Δcdpk2-immunized and orally gavaged with 10 Pru cysts on day 12 of gestation, (B) non-immunized, and orally gavaged with 10 Pru cysts on day 12 of gestation, and (C) non-immunized and uninfected.
  (Wang et al., 2018)
• Efficacy: Acute: All nonvaccinated and infected mice died within 10 dpi, whereas all mice vaccinated survived. Significantly elevated levels of IL-12 and IFN-γ were found in the nonvaccinated + RH-infected mice, whereas only modestly elevated levels of the same cytokines was observed in Pru:Δcdpk2 vaccinated + RH-infected mice.
  Chronic: All vaccinated mice survived, whereas only 40% of nonvaccinated infected mice survived. Pru:Δcdpk2-vaccinated mice had significantly less brain cyst burden(78 ± 48 cysts/brain compared to 4296 ± 687 cysts/brain) (P < .001).
  Congenital: Body weight of neonates born to Pru:Δcdpk2-vaccinated dams was similar to neonates born to nonvaccinated uninfected dams. In contrast, the litter size and body weight of pups of nonvaccinated + infected mice were significantly lower. The average brain cyst number in all neonates (n = 19) born to nonvaccinated + infected dams was 919 ± 339. In contrast, 41.4% (24/58) of neonates born to vaccinated dams had an average brain cyst number of (60 ± 33). The brain of 58.6% (34/58) of neonates born to vaccinated + infected dams revealed no cysts. The average brain cyst number was significantly higher in nonvaccinated + infected dams (3287 ± 569 cysts/brain) than in that of vaccinated dams (77 ± 58 cysts/ brain).
  (Wang et al., 2018)