• Vaccine Name: CAV-2-ROP16
• Target Pathogen: Toxoplasma gondii
• Target Disease: Toxoplasmosis
• Type: Recombinant vector vaccine
• Status: Research
• Host Species for Licensed Use: Human
• Host Species as Laboratory Animal Model: mouse
• Antigen: ROP16: Rhoptry protein 16: a specialised kinase released from rhoptries into the host cell during invasion, directly target the host cell nucleus and activate both the signal transducer and activator of transcription 3 and 6 (STAT3 and STAT6) signaling pathways. (Li et al., 2016)
• ROP16 gene engineering:
  • Type: Recombinant vector construction
  • Description: pPolyII-CAV-△E3-ROP16 was constructed. The Kpn I fragment containing the E3 region of CAV-2 from pPolyII-CAV-2 was cloned to pVAX. RPO16 was amplified by PCR using a forward primer introducing Nhe I recognition sites and a reverse primer introducing Bgl II recognition sites. ROP16 was identified, purified, and then cloned to pVAX-E3 vector. The 6.7 kb fragment of Nru I and Sal I double-digested pVAX-ΔE3-ROP16, containing the ROP16 expression cassette flanked by residual E3 sequences, and was cloned back into pPolyII-CAV-2. The recombinant viruses was then generated in MDCK cells. (Li et al., 2016)
  • Detailed Gene Information: Click Here.
• Immunization Route: Intramuscular injection (i.m.)
• Description: Recombinant canine adenovirus expressing the ROP16 gene of the RH strain of T. gondii (Li et al., 2016)

Mouse Response

• Host Strain: BALB/c mice (Li et al., 2016)
• Host age: eight weeks old (Li et al., 2016)
• Host gender: female (Li et al., 2016)
• Vaccination Protocol: The mice were randomly assigned to four experimental groups (23 mice per group). Group I was intramuscularly inoculated once with 0.1 ml CAV-2-ROP16 (108.0 PFU/ml); group II received 0.1 ml CAV-2 (108.25 PFU/ml) once intramuscularly; group III was inoculated once intramuscularly with 0.1 ml PBS; and group IV was not given any injection. Group 2, 3, and 4 are negative controls. (Li et al., 2016)
• Immune Response: Humoral: The antibody titres of ROP16 were drastically enhanced in CAV-2-ROP16 group compared to the controls. The ratio of IgG1 to IgG2a in CAV-2-ROP16 group was significantly higher than that of the controls (P < 0.05). (Li et al., 2016)
  Cellular: Values of IFN-γ and IL-2 in the CAV-2-ROP16 group were significantly higher than the control groups (P < 0.05). Low concentration of IL-4 showed a weak but obviously proliferative response in CAV-2-ROP16 group compared to the other control groups (P < 0.05). There were no statistically significant differences in the levels of IL-10 in all groups (P > 0.05). There was significant increase in IFN-γ and TNF-α production that was induced by CD4+ and CD8+ T cells, respectively in the mice vaccinated with CAV-2-ROP16 compared to the other three groups (P < 0.05). The percentage of CD3+/CD4+ and CD3+/CD8+ T-cells were significantly increased in mice vaccinated with CAV-2-ROP16 compared to the other three groups (P < 0.05).(Li et al., 2016)
• Challenge Protocol: Eight weeks after the prime immunisation, 20 mice in all groups were challenged intraperitoneally (i.p.) with 1 × 10^3 tachyzoites of the virulent T. gondii RH strain. The mice were observed daily for mortality. (Li et al., 2016)
• Efficacy: The mice vaccinated with a single dose of CAV-2-ROP16 displayed 25% protection 80 days after RH strain infection; the administration of either CAV-2 or PBS did not prevent mortality, that all mice received CAV-2 or PBS died within seven days. (Li et al., 2016)