• Vaccine Name: rTgADF
• Target Pathogen: Toxoplasma gondii
• Target Disease: Toxoplasmosis
• Type: Subunit vaccine
• Status: Research
• Host Species for Licensed Use: Human
• Host Species as Laboratory Animal Model: mouse
• Antigen: TgADF (Liu et al., 2016)
• TgADF gene engineering:
  • Type: Recombinant protein preparation
  • Description: ORF of TgADF was amplified using PCR from the cDNA template with forward primer introducing BamHI site and reverse primer introducing XhoI site. The PCR products were cloned into the ppET30a(+) vector and transformed into E. coli DH5α competent cells. rTgADF was harvested from E. coil and was purified. (Liu et al., 2016)
  • Detailed Gene Information: Click Here.
• Immunization Route: Nasal spray
• Description: T. gondii subunit vaccine of recombinant TgADF. (Liu et al., 2016)

Mouse Response

• Host Strain: BALB/c (Liu et al., 2016)
• Vaccination Protocol: The mice were randomly divided into 5 groups (8 mice per group). Four groups were intranasally administered with 10, 20, 30, or 40 μg of rTgADF that was separately dissolved in 20 μL of phosphate-buffered saline (PBS). The control group was immunized with PBS. On days 0, 14, and 21, the nostrils of the mice were slowly instilled with rTgADF protein solution (10 μL per nostril). (Liu et al., 2016)
• Immune Response: Mucosal: Significantly higher levels of sIgA titers were observed in the nasal, intestinal, and vesical washes in mice immunized with 20, 30, or 40 μg of rTgADF than in the control groups (P < 0.05). The sIgA levels in three mucosal washes in the 30- and 40-μg groups were prominently higher than that in the 20-μg group. Moreover, an apparent predominance of the 30-μg group over the 40-μg group was observed on the basis of the vesical washes. (Liu et al., 2016)
  Humoral: High IgG titers were detected in the serum samples of all immunized mice (P < 0.05). The OD values for IgG were continuously increased following an increase in the immunization dosage, and the 40-μg group showed the highest titer among all the immunized groups (P < 0.01). (Liu et al., 2016)
  Cellular: Splenocytes from the 30-μg and 40-μg groups exhibited a significantly greater proliferative response to rTgADF than splenocytes from the control group. Splenocytes from all the immunized groups secreted significantly high levels of IFN-γ and IL-2 when compared with the control group, and the highest levels were elicited by 30 μg of rTgADF. In contrast, IL-4 and IL-10 levels displayed no significant changes between the immunized and control groups (P > 0.05). (Liu et al., 2016)
• Challenge Protocol: Two groups of BALB/c mice (30 mice per group) were immunized with PBS or 30 μg of rTgADF as mentioned in vaccination protocol. Twenty-two mice from each group were intragastric administrated with a dose of 4 × 10^4 tachyzoites for the acute assay. Survival times of the infected mice were recorded daily. The other 8 mice per group were challenged with 1 × 10^4 tachyzoites for the chronic model. Four weeks later, real-time PCR was used to quantify tachyzoite loads in the liver and brain for detecting the SAG1 gene. (Liu et al., 2016)
• Efficacy: Acute: Most of the mice in the control group were dead within 9 days post-infection, with the last mouse dying on the 23rd day. However, 36.36 % of the mice immunized with 30 μg of rTgADF remained alive 30 days post-infection. (Liu et al., 2016)
  Chronic: The tachyzoite load in the livers and brains was significantly lower in the immunized mice {13.89 ± 1.27 (105/g) and 6.33 ± 0.43 (105/g), respectively)} than in the control mice {43.09 ± 3.03 (105/g) and 12.92 ± 3.30 (105/g), respectively}, which showed a reduction in the tachyzoite load by 67.77 % in the liver and 51.01 % in the brain when compared with the control group. (Liu et al., 2016)