• Vaccine Name: T. gondii LDH1 and LDH2 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: deleted LDH1 and LDH2 gene in T. gondii PruΔKu80::hxgprt strain (Abdelbaset et al., 2017)

Mouse Response

• Host Strain: BALB/c (Abdelbaset et al., 2017)
• Host age: Eight weeks old (Abdelbaset et al., 2017)
• Host gender: female (Abdelbaset et al., 2017)
• Vaccination Protocol: Mice were vaccinated with a low-dose with 10^3 tachyzoites of the parental PruΔKu80::hxgprt strain or LDH knockout strains (ΔLDH1, ΔLDH2, or ΔLDH1ΔLDH2). A group of non-vaccinated mice was kept as control. (Abdelbaset et al., 2017)
• Side Effects: Infection study:
  Infection with 10^6 tachyzoites: parental or Δldh2 strain infected mice demonstrated a 10 and 0% survival rate, respectively. On the other hand, mice challenged with Δldh1 and Δldh1Δldh2 strains demonstrated a 60 and 30% survival rate, respectively. Average number of cysts in each group was 680 (parental, n = 1), 177 ± 62 (Δldh1, n = 6), no data (Δldh2, n=0) and 60 ± 40 (Δldh1Δldh2, n = 3).
  Infection with 10^4 tachyzoites: parental and Δldh2 strain infected mice demonstrated a 60 and 40% survival rate, respectively. On the other hand, Δldh1 and Δldh1Δldh2 strain infected mice showed 100% survival. Average number of cysts in each group was 231 ± 116 (parental, n = 6), 27 ± 7 (Δldh1, n = 10), 52 ± 11 (Δldh2, n = 4), and 1 ± 1 (Δldh1Δldh2, n = 10)
  Infection with 10^3 tachyzoites: parental, Δldh1 and Δldh1Δldh2 strain infected mice showed 100% survival. Δldh2 infected mice showed low (10%) mortality. Average number of cysts in each group was 640 ± 72 (parental, n = 4), 56 ± 5 (Δldh1, n = 5), 330 ± 34 (Δldh2, n = 5), and 0 (Δldh1Δldh2, n = 5)
  (Abdelbaset et al., 2017)
• Challenge Protocol: 30 days after vaccination, mice were challenged with 100 highly virulent (LD100) RH strain parasites. (Abdelbaset et al., 2017)
• Efficacy: All mice in the naïve group died within 11 days after challenge, one mouse died in parental strain infected group, and all mice survived in the other vaccinated groups. (Abdelbaset et al., 2017)