• Vaccine Name: ISA 201-rTgCST2
• Target Pathogen: Toxoplasma gondii
• Target Disease: Toxoplasmosis
• Type: Subunit vaccine
• Status: Research
• Host Species for Licensed Use: Human
• Antigen: recombinant TgCST2 protein (Tian et al., 2022)
• TgCST2 gene engineering:
  • Type: Recombinant protein preparation
  • Description: TgCST2 95-325aa was amplified and then constructed to the expression vector pET-30a. Escherichia coli strain BL-21 (DE3) system was used for protein expression. The recombinant protein was purified and the endotoxin was removed using His Bind® Resin Chromatography kit (Merck, Darmstadt, Germany) and Detoxi-Gel Affinity Pak Prepacked columns (Pierce, Rockford, USA). (Tian et al., 2022)
  • Detailed Gene Information: Click Here.
• Immunization Route: subcutaneous injection
• Description: T. gondii subunit vaccine that uses recombinant TgCST2 protein as antigen and ISA 201 as adjuvant (Tian et al., 2022)

Mouse Response

• Host Strain: BALB/c mice (Tian et al., 2022)
• Host age: Six-week-old (Tian et al., 2022)
• Host gender: female (Tian et al., 2022)
• Vaccination Protocol: A total of 60 BALB/c mice were randomized into three groups (20/group), 20 µg of rTgCST2 was immunized subcutaneously each mouse with an equal volume of ISA 201 (Seppic, France) and mice immunized ISA 201 alone or PBS only were enrolled as controls. All mice were vaccinated 3 times at 2-week intervals. (Tian et al., 2022)
• Immune Response: Humoral: Anti-rTgCST2 titers reached up to 1:10^4 for vaccinated mice. Serum IgG levels induced by rTgCST2 had a substantial increase compared with control groups (P < 0.001). Both IgG1 and IgG2a levels induced by rTgCST2 showed considerable rise after inoculation (P < 0.001), IgG1 was the predominant subtype. (Tian et al., 2022)
  Cellular: On 6 weeks post-vaccination, only the levels of IFN-γ and IL-10 in ISA201-rTgCST2 immunized groups were significantly higher (P  <  0.05 and P < 0.001, respectively) than the control groups. (Tian et al., 2022)
• Challenge Protocol: Two weeks after the last vaccination, 10 immunized mice per group were challenged intraperitoneally with 1 × 10^2 tachyzoites of RH T. gondii strain and 10 additional mice were challenged intragastrically with 10 cysts of PRU strain. (Tian et al., 2022)
• Efficacy: Intraperitoneal inoculation of 10^2 RH strain tachyzoites induced all death of the mice within 9 days after challenge. There was no significant difference in survival time between two control groups (PBS and ISA 201, P > 0.05). The survival time of mice immunized with ISA 201-rTgCST2 was significantly longer than that of PBS group (P < 0.001). (Tian et al., 2022)
  After 2 months of observation, 10 of 10 mice infected orally with 10 cysts of PRU strain in ISA 201-rTgCST2 immunized group survived. However, only one animal in the ISA 201 group and two animals in the PBS group died throughout the experiment. Brain cyst burdens in ISA 201-rTgCST2 immunized group had decreased a bit compared with PBS control groups (reduction by 36.4%, P < 0.05). Meanwhile, compared with PBS control groups, there displayed a reduction in brain cyst diameter of ISA 201-rTgCST2 immunized group (P > 0.05, reduction by 16.7%). (Tian et al., 2022)