• Vaccine Name: rTgRACK1
• Target Pathogen: Toxoplasma gondii
• Target Disease: Toxoplasmosis
• Type: Subunit vaccine
• Status: Research
• Host Species for Licensed Use: Mouse
• Antigen: TgRACK1 (Wang et al., 2014)
• TgRACK1 gene engineering:
  • Type: Recombinant protein preparation
  • Description: First strand cDNA was synthesised from the total RNA extracted from tachyzoites of T. gondii. TgRACK1 was amplified by PCR, which introduced EcoRI and NotI sites. The PCR product was digested and cloned into pGEX-6P-1 vector. The resulting pGEX-6P-1-TgRACK1 plasmid was transformed into E. coli BL21 (DE3) host cells. rTgRACK1 was harvested from E. coil and purified. (Wang et al., 2014)
  • Detailed Gene Information: Click Here.
• Immunization Route: Nasal spray
• Description: T. gondii subunit vaccine of recombinant TgRACK1 (Wang et al., 2014)

Mouse Response

• Host Strain: BALB/c (Wang et al., 2014)
• Vaccination Protocol: Fifty 6-week-old female BALB/c mice were randomly divided into five groups (10 per group) and were intranasally immunized with 15, 25, 35 or 45 μg of rTgRACK1 dissolved in 20 μl sterile phosphate-buffered saline (PBS) on days 0, 14, and 21. Control mice received PBS alone. (Wang et al., 2014)
• Immune Response: Mucosal: The sIgA antibody titers in the nasal washes of the rTgRACK1-treated groups were significantly higher than those of the PBS control, with the highest titer of sIgA antibody detected in the 35 μg rTgRACK group (P<0.01). sIgA levels from the intestinal and vesical washes were higher in 25, 35, 45 μg rTgRACK1 groups, and 35 μg rTgRACK1 could also elicit the highest sIgA levels in intestinal and vesical washes (P < 0.01). Enhanced production of both IFN-γ and IL-2 were detected in the 25 μg rTgRACK1 group (P < 0.05) and reached higher levels in the 35 and 45 μg rTgRACK1 groups (P < 0.01). (Wang et al., 2014)
  Humoral: Significantly increased levels of total IgG and IgA antibodies were observed in the 25, 35 and 45 μg rTgRACK1 groups compared to the control group (P < 0.05). The maximum IgG antibody response was detected in the 35 μg rTgRACK1-treated group. A mixed IgG1/IgG2a response with predominant IgG2a production was detected. (Wang et al., 2014)
  Cellular: Significant productions of IFN-γ, IL-2 and IL-4 were all evident at 25 μg rTgRACK1 treatment and reached a maximum level at 35 μg rTgRACK1. No significant changes in production of IL-10 were seen (P>0.05). (Wang et al., 2014)
• Challenge Protocol: Mice immunised with 35 μg of rTgRACK1 and PBS control mice (30 mice/group, 10 mice for chronic infection and 20 mice for lethal assay) were orally challenged with either 1 × 10^4 tachyzoites for the chronic infection or 4 × 10^4 tachyzoites for an acute infection on the fifteenth day after the last immunisation.The time to death of the challenged mice was monitored for the acute challenge. On the 31st day, the numbers of tachyzoite in the murine brains and livers of the chronic challenge mice were determined by real-time PCR assay. (Wang et al., 2014)
• Efficacy: Chronic: Significant reductions of tachyzoite were observed in both the brain and liver tissues of rTgRACK1-immunised mice (1.12 ± 0.17 × 10^6/g and 2.61 ± 0.28 × 10^6/g respectively) in comparison with those of PBS controls (2.09 ± 0.32 × 106/g and (5.63 ± 0.74) × 10^6/g, respectively), representing a 57.09% reduction in brain (P < 0.01) and 53.64% reduction in liver (P < 0.01) with rTgRACK1 vaccination. (Wang et al., 2014)
  Acute: The death time of mice immunised with 35 μg rTgRACK1 was between 8 and 21 days after the challenge, while all of the mice in the PBS control group died from 6 to 10 days after the challenge, representing significantly increase in the survival rate of vaccinated mice (approximately 45%) (P < 0.01). (Wang et al., 2014)