• Vaccine Name: T. gondii DNA vaccine encoding multi-epitope ROP8
• Target Pathogen: Toxoplasma gondii
• Target Disease: Toxoplasmosis
• Type: DNA vaccine
• Status: Research
• Host Species for Licensed Use: Human
• Antigen: ROP8: expressed in tachyzoite and bradyzoite stages. Involved in the pathogenicity of the parasite as well as host cell modulation, critical for acute virulence of T. gondii. (Foroutan et al., 2020)
• ROP8 gene engineering:
  • Type: DNA vaccine construction
  • Description: The linear B cell epitopes, major histocompatibility complex (MHC) class I and class II molecules for ROP8 protein were predicted using bioinformatic tools. MHC I, MHC II, and linear B-cell epitopes were linked together by the SAPGTP linker, and the Kozak sequence was added at N-terminal. Several physico-chemical parameters, post translational modifications, and the secondary and tertiary structure for the multi-epitope peptide were predicted. The final sequence of the peptide was sent for the construction and cloning into eukaryotic expression vector pcDNA3.1. (Foroutan et al., 2020)
  • Detailed Gene Information: Click Here.
• Immunization Route: subcutaneous injection
• Description: Multi-epitope DNA vaccine encoding the potential B and T-cell epitopes from ROP8 protein using eukaryotic expression vector pcDNA3.1. (Foroutan et al., 2020)

Mouse Response

• Host Strain: BALB/c mice (Foroutan et al., 2020)
• Host age: 6–8 weeks (Foroutan et al., 2020)
• Host gender: female (Foroutan et al., 2020)
• Vaccination Protocol: Three groups of BALB/c mice (8 per experimental group) were immunized on days 0, 21, and 42 with 100 μg of plasmid DNA suspended in 100 μl sterile endotoxin free PBS (100 μg/100 μl), including two control groups (PBS and empty pcDNA3.1 vector). (Foroutan et al., 2020)
• Immune Response: Humoral: Significantly high levels of IgG antibodies were detected post vaccination with multi-epitope ROP8 vaccine compared with PBS and empty pcDNA3.1 vector (P < 0.05). The multi-epitope vaccine elicited both IgG1 and IgG2a production with the predominance of IgG2a compared with control groups (P < 0.05). (Foroutan et al., 2020)
  Cellular: Spleen cells from mice vaccinated with multi-epitope ROP8 vaccine generated a significantly higher level of IFN-γ and IL-4 than the mice in the PBS and empty pcDNA3.1 vector groups (P < 0.05). The BALB/c mice vaccinated with multi-epitope vaccine have the greater splenocyte proliferative response compared with control groups (P < 0.05). (Foroutan et al., 2020)
• Challenge Protocol: Three weeks after the last immunization, five mice per group were intraperitoneally (i.p) challenged with 2 × 10^3 tachyzoite of virulent T. gondii RH strain. Their survival periods were monitored daily. (Foroutan et al., 2020)
• Efficacy: The BALB/c mice that received the multi-epitope ROP8 vaccine had prolonged survival time compared with PBS and pcDNA3 control groups (P < 0.05). (Foroutan et al., 2020)