• Vaccine Name: T. gondii DNA vaccine pVAX-GRA16
• Target Pathogen: Toxoplasma gondii
• Target Disease: Toxoplasmosis
• Type: DNA vaccine
• Status: Research
• Host Species for Licensed Use: Human
• Antigen: GRA16 (Hu et al., 2017)
• GRA16 gene engineering:
  • Type: DNA vaccine construction
  • Description: TgGRA16 gene was PCR amplified, and the PCR products were subcloned into the pVAX I and generated recombinant plasmid pVAX-GRA16. The recombinant plasmids pVAX-GRA16 were purified from transformed E. coli DH5α cells by anion exchange chromatography. (Hu et al., 2017)
  • Detailed Gene Information: Click Here.
• Immunization Route: Intramuscular injection (i.m.)
• Description: T. gondii DNA vaccine encoding GRA16 as antigen using pVAX I vector. (Hu et al., 2017)

Mouse Response

• Vaccination Protocol: A total of 4 groups were performed (28 mice per group). Mice in different groups were intramuscularly injected with pVAX-GRA16 plasmids, empty pVAX I, and PBS (100 μl/each) 3 times at a 2-week interval. The mice that received nothing were used as negative control. (Hu et al., 2017)
• Challenge Protocol: 10 mice in each group were intraperitoneally (IP) challenged with 10^3 tachyzoites of the virulent T. gondii RH strain 2 weeks after the last immunization. The survival time for each mouse and the percentages of mice survived were recorded until a fatal outcome for all animals. Meanwhile, 6 mice in all groups were inoculated orally with 10 tissue cysts as experimental chronic toxoplasmosis. One month after infection, brains of mice from each group were homogenized in 1 ml PBS. The number of cysts per brain was determined. (Hu et al., 2017)
• Efficacy: The average survival time of immunized mice (8.4 ± 0.78 days) showed an extension tendency compared to that of the control groups (7.1 ± 0.30 days), but the differences were not significant (p > 0.05).
  Compared to pVAX I, PBS, and negative control groups, immunization with pVAX-GRA16 significantly reduced brain cyst numbers in the immunized mice (p < 0.001), with a cyst reduction of 43.89%.
  (Hu et al., 2017)