• Vaccine Name: Ad-MVA PvCelTOS
• Target Pathogen: Plasmodium spp.
• Target Disease: Malaria
• Type: Recombinant vector vaccine
• Status: Research
• Host Species for Licensed Use: Human
• Antigen: PvCelTOS: cell-traversal protein for ookinetes and sporozoites of P. vivax. A protein important for parasite traversal of host cells both for ookinetes in the mosquito and for sporozoites. (Alves et al., 2017)
• PvCelTOS gene engineering:
  • Type: Recombinant protein preparation
  • Description:
  • Detailed Gene Information: Click Here.
• Immunization Route: Intramuscular injection (i.m.)
• Description: PvCelTOS (Ad): Recombinant chimpanzee adenoviral vector 63 (ChAd63) expressing PvCelTOS.
  PvCelTOS (MVA): Recombinant modified vaccinia virus Ankara (MVA) expressing PvCelTOS
  **PvCelTOS (Ad) is the primary vaccination, and PvCelTOS (MVA) is the booster. (Alves et al., 2017)

Mouse Response

• Vaccination Protocol: 3 groups of mice were used, each group includes 6 mice. Mice were intramuscularly inject prime immune 1*10^8 IU ChAd63-PvCelTOS, then intramuscularly injected one of the boosters 8 weeks later: 1*10^6 PFU per ml of 1) PvCelTOS (MVA), 2) PvCelTOS (VLPs), 3) PvCelTOS (protein) (Alves et al., 2017)
• Immune Response: Humoral: anti-PvCelTOS antibody levels significantly increased after vaccination in both types of mice. Antibody responses were boosted with all three vaccine platforms.
  Cellular:
  CD-1: Mice in Ad-MVA group had significantly higher TNF-α levels (2.93% ± 0.72% comparing to 0.98% ± 0.42%) and IFN-γ levels(3.46% ± 0.699% and 1.36% ± 0.52%). No significant difference in IL-2 levels. The total anti-PvCelTOS cellular responses were low after background values subtraction (1.9% for TNF-α and 2.1% for IFN-γ. Only the value of IFN-γ significantly higher (P < 0.0001)).
  BALB/c: All immunization regimens substantially higher levels of TNF-α- and IFN-γ-producing CD3+/CD8+ cells.
  (Alves et al., 2017)
• Challenge Protocol: Same prime-boost vaccination performed (6 mice in each BALB/c group, 10 mice in each CD1 group). Three set of mice were each challenged with 1000 sporozoits of 1) Pb-PvCelTOS (P. berghei expressing P. vivax CelTOS), 2) Wild-type P.berghei, and 3) Pb-PfCelTOS (P. berghei sporozoites expressing P. falciparum CelTOS). Sporozoits were intravenous injected 10 days after booster. Efficacy was determined by measuring the prepatent period (the time to reach 1% parasitemia after challenge). (Alves et al., 2017)
• Efficacy: Pb-PvCelTOS:
  CD1: Ad-MVA provided 10% sterile protection, not significantly higher than the control
  BALB/c: no vaccination regimen conferred any protective efficacy even though it induced protective cellular and humoral immune responses.
  Pb-PfCelTOS: no protective immunity in CD1 mice.
  Wild-type P. berghei: no protective immunity from any immunization regimen in CD1 mice.
  (Alves et al., 2017)