• Vaccine Name: T. gondii DNA vaccine pVAX-ROP38
• Target Pathogen: Toxoplasma gondii
• Target Disease: Toxoplasmosis
• Type: DNA vaccine
• Status: Research
• Host Species for Licensed Use: Human
• Antigen: ROP38: Rhoptry protein 38: an active rhoptry protein kinase (ROPK) that could have an inhibitory effect on host cell transcription by down-regulating the MAPK signaling track, observed inside rhoptries. (Xu et al., 2014)
• ROP38 gene engineering:
  • Type: DNA vaccine construction
  • Description: Amplified by PCR using a forward primer introducing Kpn I recognition sites and a reverse primer introducing Xba I recognition sites. The amplified ROP38 was purified and was inserted into the pVAX I vector. (Xu et al., 2014)
  • Detailed Gene Information: Click Here.
• Immunization Route: Intramuscular injection (i.m.)
• Description: T. gondii DNA vaccine encoding ROP38 using pVAX I vector. (Xu et al., 2014)

Mouse Response

• Host Strain: Specific-pathogen-free (SPF) grade Kunming mice (Xu et al., 2014)
• Host age: six to eight weeks old (Xu et al., 2014)
• Host gender: female (Xu et al., 2014)
• Vaccination Protocol: Three groups of mice (28 per group) were injected with 100 μl diluted pVAX-ROP38 DNA vaccine, PBS or empty pVAX I plasmid, respectively. Another group of 28 mice were kept as blank control without injection. Mice in the pVAX-ROP38 DNA vaccine, PBS and pVAX I groups were vaccinated three times with a two-week interval. (Xu et al., 2014)
• Immune Response: Humoral: Compared with the three control groups, a statistically significantly higher level of IgG antibody was detected in the sera of mice immunized with pVAX-ROP38 (P < 0.01), and the OD values of IgG were continuously increased with successive DNA immunization. The levels of IgG1 and IgG2a in the experimental group (immunized with TgROP38) were also the highest (P < 0.01). A significantly higher IgG2a value than IgG1 was detected. (Xu et al., 2014)
  Cellular: The percentage of CD3+ CD4+ CD8- and CD3+ CD8+ CD4- T lymphocytes in the pVAX-ROP38 group were significantly higher than those in the control groups, respectively (P < 0.01). There were no significantly differences in the ratio of CD8+/CD4+ between mice immunized with pVAX-ROP38 and in controls (P > 0.05). A significantly high level of both IFN-γ and IL-2 in the pVAX-ROP38 group was detected in pVAX-ROP38 group compared with that in the three control groups (P < 0.05). (Xu et al., 2014)
• Challenge Protocol: Two weeks after the last immunization, 10 mice in each group were challenged intraperitoneally with 1000 tachyzoites of the virulent T. gondii RH strain, and other 6 mice were inoculated with 10 cysts of the attenuated virulent PRU strain orally. Mice injected with RH strain were observed twice a day for mortality until a fatal outcome for all animals. The brain cysts were determined one month after the challenge infection. Each brain was homogenized in 2 ml PBS, and the mean number of cysts per brain was calculated. (Xu et al., 2014)
• Efficacy: RH: The average survival time of mice in the pVAX-ROP38 group was slightly longer than that of the three control groups, but the difference was not statistically significant (P > 0.05). (Xu et al., 2014)
  PRU: The number of brain cysts in mice from the pVAX-ROP38 group was significantly decreased (76.6%) compared to that of the three control groups (P <0.01). (Xu et al., 2014)