• Vaccine Name: T. gondii DNA vaccine pSAG5B/SAG5C
• Target Pathogen: Toxoplasma gondii
• Target Disease: Toxoplasmosis
• Type: DNA vaccine
• Status: Research
• Host Species for Licensed Use: Human
• Antigen: SAG5B and SAG5C: sequence branches of surface antigen protein 5, transcribed in T. gondii tachyzoites and bradyzoites, play an important role in cyst persistence in the host. (Lu et al., 2017)
• SAG5B gene engineering:
  • Type: DNA vaccine construction
  • Description: Amplified by PCR. The PCR products from SAG5B and SAG5C genes were cloned into the pEASY-T1 vector and digested with restriction enzymes. The SAG5B and SAG5C fragments were purified and inserted into the mammalian expression vector pBudCE4.1 to produce pSAG5B and pSAG5C. The NotI/KpnI fragment encoding SAG5B was excised and cloned into the HindIII/XbaI sites of the pSAG5C to produce pSAG5B/SAG5C. (Lu et al., 2017)
  • Detailed Gene Information: Click Here.
• SAG5C gene engineering:
  • Type: DNA vaccine construction
  • Description: Amplified by PCR. The PCR products from SAG5B and SAG5C genes were cloned into the pEASY-T1 vector and digested with restriction enzymes. The SAG5B and SAG5C fragments were purified and inserted into the mammalian expression vector pBudCE4.1 to produce pSAG5B and pSAG5C. The NotI/KpnI fragment encoding SAG5B was excised and cloned into the HindIII/XbaI sites of the pSAG5C to produce pSAG5B/SAG5C. (Lu et al., 2017)
  • Detailed Gene Information: Click Here.
• Immunization Route: Intramuscular injection (i.m.)
• Description: Multi-antigenic DNA vaccine that express SAG5B and SAG5C using mammalian expression vector pBudCE4.1. (Lu et al., 2017)

Mouse Response

• Host Strain: BALB/c mice (Lu et al., 2017)
• Host age: Eight-week-old (Lu et al., 2017)
• Host gender: female (Lu et al., 2017)
• Vaccination Protocol: Mice were divided randomly into five groups (28 in each group) and were immunized four times on weeks 0, 2, 4, and 6. Three experimental groups were immunized with 100 μL of PBS containing 100 μg pSAG5B, 100 μg pSAG5C, or 100 μg pSAG5B/SAG5C . The other two mouse groups (the controls) were injected with the empty vector or with PBS. (Lu et al., 2017)
• Immune Response: Humoral: The IgG levels for the experimental mice increased gradually over time. Significant differences were found in the sera of mice vaccinated using pSAG5B, pSAG5C, or pSAG5B/SAG5C compared with the mice injected with PBS or pBudCE4.1 (P < 0.05). Moreover, IgG levels in the pSAG5B/SAG5C-immunized mice were significantly higher compared with the mice immunized with the single-gene (P < 0.05). A predominance of IgG2a over IgG1 was observed. (Lu et al., 2017)
  Cellular: The IFN-γ levels in mice immunized with pSAG5B, pSAG5C, or pSAG5B/SAG5C were significantly higher than those of the mice immunized with PBS or pBudCE4.1 (P < 0.05). The pSAG5B/SAG5C-immunized mice generated the highest IFN-γ level. The pSAG5C-immunized mice generated a higher level of IFN-γ than the pSAG5B-immunized mice, but no significant difference was found between these two groups (P > 0.05). The splenocyte supernatant IL-4 levels of all groups were similar (P > 0.05). (Lu et al., 2017)
• Challenge Protocol: Two weeks after the final inoculation (day 56), 12 mice from each group were challenged intraperitoneally with 1 × 10^4 tachyzoites of the highly virulent T. gondii RH strain, while another 12 mice from each group were infected intragastrically with 20 cysts of the T. gondii PRU strain. The mice challenged with the RH strain were observed and those that showed signs of illness were sacrificed immediately using CO2 gas. (Lu et al., 2017)
• Efficacy: RH: The survival time of the mice immunized with pSAG5B (8.5 ± 0.53), pSAG5C (7 ± 0.56) or pSAG5B/SAG5C (12.3 ± 0.68) was longer than that of the PBS-immunized mice (3.8 ± 0.24) or the pBudCE4.1-immunized mice (3.9 ± 0.26) (P < 0.05). Mice in the pSAG5B/SAG5C immunization group survived longer (17 days) than the mice immunized with the single gene (P < 0.05), while the number of survival days for the single gene groups were similar (P > 0.05). (Lu et al., 2017)
  PRU: Mice in the pSAG5B, pSAG5C, and pSAG5B/SAG5C groups showed significantly fewer brain cysts than the PBS- or pBudCE4.1-immunized mice (P < 0.05). Brain cyst numbers in the mice vaccinated with pSAG5B/SAG5C were much lower than those of the other mouse groups (P < 0.05). (Lu et al., 2017)