• Vaccine Name: GRA7(20–28)SAPN
• Target Pathogen: Toxoplasma gondii
• Target Disease: Toxoplasmosis
• Type: Subunit vaccine
• Status: Research
• Host Species for Licensed Use: None
• Antigen: GRA7(20-28) peptide (LPQFATAAT) (El et al., 2014)
• GRA7 gene engineering:
  • Type: Recombinant protein preparation
  • Description: The GRA7(20–28) peptide sequence was cloned in between the NsiI/BamHI restriction sites of the modified pPEP-T vector to yield the final LP amino acid sequence. The sequence is composed of the his-tag sequence (1-12aa), the CD8+ epitope (13-21aa), the pentameric coiled coil (22-60aa), a glycine-glycine linker (61-62aa), the trimeric coiled coil (63-107aa) and a solubility tag (108-128). The trimeric coiled coil contains a PADRE derivative as a CD4+ epitope (86-98aa). LP monomer was expressed in E. coil, purified, and eventually self-assembled to form nanoparticles (GRA7(20-28)SAPN). (El et al., 2014)
  • Detailed Gene Information: Click Here.
• Immunization Route: subcutaneous injection
• Description: Self-assembling nanoparticles displaying the GRA7(20–28) in conjunction with PADRE. (El et al., 2014)

Mouse Response

• Host Strain: HLA-B*0702 transgenic mice: express a chimeric HLA-B07/H2-Db MHC Class I Molecule and are on a C57BL/6 × Balb/C background backcrossed through many generations (El et al., 2014)
• Vaccination Protocol: Mice were inoculated subcutaneously with 50 μg GRA7(20–28) SAPN or P4c-RD control SAPN three times at two weeks intervals. (El et al., 2014)
• Immune Response: Increase of IFN-γ secretion (El et al., 2014)
• Challenge Protocol: RH: Mice (n = 5 per group) were challenged i.p. with 2000 RH T. gondii expressing stable YFP. Peritoneal fluid was collected 120 h post infection and parasite fluorescence and numbers were measured using a fluorometer and hemocytometer, respectively. (El et al., 2014)
  Me49: Mice (n = 6 for PBS(negative control) and GRA7(20–28)SAPN, n = 3 for ΔRPS13(positive control)) were challenged intraperitoneally 14 days post-immunization using 2000 Me49-FLUC tachyzoites and were imaged 21 days post-challenge. Mice were then euthanized, and the number of tissue cysts per brain were counted. (El et al., 2014)
• Efficacy: RH: Fluorescence from GRA7(20–28)SAPN immunized mice was significantly lower than the control. (El et al., 2014)
  Me49: The numbers of luciferase expressing parasites in mice immunized with GRA7(20–28)SAPN were significantly reduced compared to the mice immunized with control SAPN or PBS. This correlates with the reduction of the number of cysts per brain in GRA7(20–28)SAPN immunized mice. (El et al., 2014)