• Vaccine Name: rTgROP17
• 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: ROP17 (Wang et al., 2014)
• ROP17 gene engineering:
  • Type: Recombinant protein preparation
  • Description: ORF of the TgROP17 gene was amplified by RT-PCR and was cloned into the pGEX-6P-1 vector. The recombinant plasmid was transferred into E. coli DH5a and were selected. The successful pGEX-6P-1/TgROP17 construct was transformed into E. coli Rosetta (DE3). The rTgROP17 protein was express in E. coli Rosetta (DE3) cells, purified, and the endotoxin in rTgROP17 was removed. (Wang et al., 2014)
  • Detailed Gene Information: Click Here.
• Immunization Route: Nasal spray
• Description: T. gondii subunit vaccine of recombinant ROP17 (Wang et al., 2014)

Mouse Response

• Host Strain: BALB/c (Wang et al., 2014)
• Host age: 6 weeks (Wang et al., 2014)
• Host gender: female (Wang et al., 2014)
• Vaccination Protocol: Mice were randomly divided into 5 groups (8 mice per group) and were immunized nasally with 20 µl PBS containing 15, 25, 35 or 45 µg of rTgROP17. The control mice were given PBS solution only. All animals were vaccinated three times on days 0, 14, and 21. (Wang et al., 2014)
• Immune Response: Humoral: The total IgG antibody productions of the mice immunized with 35 and 45 µg rTgROP17 were significantly higher than those of the control group (P<0.01) but not significantly different from each other (P>0.05). 25 µg but not 15 µg rTgROP17 elicited elevated IgG antibody levels compared to the control groups (P<0.05). Both IgG1 and IgG2a were detected in the sera of all the mice immunized with rTgROP17, and greater levels of IgG2a were detected than IgG1 in general. (Wang et al., 2014)
  Cellular: 35 µg and 45µg rTgROP17 significantly stimulated the production of IFN-γ(P<0.01), IL-2(P<0.01), and IL-4 (P<0.05) over the PBS control group. 25 µg rTgROP17 also stimulated the production of IFN-γ and IL-2 (P<0.05) but not IL-4 (P>0.05). 15 µg rTgROP17 did not stimulated the production of IFN-γ, IL-2, or IL-4 (P>0.05). No significant difference was observed for the levels of IL-5 between the rTgROP17-vaccinated and PBS control mice (P>0.05). The splenocyte stimulation indices (SIs) of the mice in 35 and 45 µg rTgROP17 groups were significantly greater than those in 15 µg rTgROP17 group or PBS control (P<0.01). The SI of the 25 µg group was greater than that of the PBS control (P<0.05). No significant difference was found for the SIs of the 15 µg group and PBS controls (P> 0.05). (Wang et al., 2014)
  Mucosal: Higher levels of SIgA were detected in the nasal, vaginal and intestinal washes of rTgROP17-immunized mice compared to those of their PBS controls (35 and 45 µg: P<0.01; 25 µg: P<0.05). (Wang et al., 2014)
• Challenge Protocol: Mice at 6 weeks of age were randomly divided into two groups (20 mice per group) and vaccinated intranasally with 35 µg of rTgROP17 or GST control in 20 µl volumes on days 0, 14, and 21. On day 14 after the final immunization, 8 mice from each group were orally challenged with 1×10^4 tachyzoites of the RH strain for chronic assay, and the other 12 mice from each group were challenged with 4×10^4 tachyzoites for acute infection. (Wang et al., 2014)
• Efficacy: Chronic infection: The tachyzoite loads in the brains and livers of the mice immunized with 35 µg rTgROP17 were significantly reduced to 59.17% (P<0.01) and 49.08% (P<0.05) of the loads found in the GST-treated control mice, respectively (Wang et al., 2014)
  Acute infection: The survival rates of the mice in rTgROP17 group were significantly increased (75%) on the 30th day after the challenge when compared to those in GST-treated control group (25%) (P<0.01). Survival of rTgROP17-immunized mice was three times over the GST-treated mice. The death time of the control mice ranged from 5 to 9 days, while the mice immunized with rTgROP17 died between days 10 and 14 after the challenge. (Wang et al., 2014)