• Vaccine Name: PfRH5 DNA Vaccine
• Target Pathogen: Plasmodium spp.
• Target Disease: Malaria
• Type: DNA vaccine
• Status: Research
• Host Species for Licensed Use: None
• Antigen: PfRH5: reticulocyte-binding protein homolog 5, a leading blood-stage antigen to APCs. The vaccine uses PfRH5ΔNL, the crystal structure and key functional antibody epitopes for the trunacated version of PfRH5. (Bjerkan et al., 2021)
• RH5 gene engineering:
  • Type: Recombinant protein preparation
  • Description: The crystal structure and key functional antibody epitopes for the truncated version of PfRH5 were characterized to create PfRH5ΔNL, used as the vaccine antigen. (Bjerkan et al., 2021)
  • Detailed Gene Information: Click Here.
• Preparation: DNA vaccines were encoded in a pUMVC4a plasmid vector (Aldevron) under a CMV-IE promoter and containing a tPA signal peptide. The targeted constructs were cloned into pUMVC4a using PmlI and BamHI.(Bjerkan et al., 2021)
• Immunization Route: Intramuscular injection (i.m.)
• Description: The PfRH5 DNA Vaccine vaccine is designed as bivalent homodimers where each chain is composed of an amino-terminal single chain fragment variable (scFv) targeting unit specific for major histocompatibility complex class II (MHCII) expressed on APCs, and a carboxyl-terminal antigenic unit genetically linked by the dimerization units. This vaccine uses PfRH5ΔNL as the antigen, with the APC-targeted vaccine construct, termed a “Vaccibody”. (Bjerkan et al., 2021)

Mouse Response

• Host Strain: Female BALB/c mice
• Vaccination Protocol: For intramuscular (i.m.) delivery of DNA vaccines, mice were shaved on each leg, and 25 µg of PfRH5ΔNL-containing DNA or 2.5 µg of PvDBP-containing DNA was injected in a 50 µl volume into each quadriceps femoris muscle (50 µg or 5 µg total DNA/mouse, respectively). Immediately after injection, electrical pulses were applied at the injection site. BALB/c mice were immunized three times at three weeks intervals, with 50 µg plasmids that encoded either MHCII-targeted or non-targeted Vaccibodies, or antigen alone. (Bjerkan et al., 2021)
• Immune Response: Vaccination with the MHCII-targeted vaccine showed significantly increased levels of total PfRH5FL-specific IgG compared to vaccination with the antigen alone at days 41 and 62 post-prime vaccination. The results showed that vaccination with the MHCII-targeted-PfRH5ΔNL vaccine induced significantly higher levels of IFN-γ producing cells in response to PfRH5FL protein in both spleens and dLNs as compared to vaccination with the non-targeted control vaccine and PfRH5ΔNL antigen alone. Strong and comparable levels of GIA were detected for IgG raised following DNA vaccination with PfRH5ΔNL-containing vaccines and the PfRH5ΔNL control vaccine. (Bjerkan et al., 2021)