• Vaccine Name: ChAd63-MVA ME-TRAP
• Target Pathogen: Plasmodium spp.
• Target Disease: Malaria
• Type: Recombinant vector vaccine
• Status: Clinical trial
• Host Species for Licensed Use: Human
• Antigen: ME-TRAP: multiple epitope thrombospondin-related adhesion protein of the pre-erythrocyte stage P.falciparum (Mensah et al., 2016)
• TRAP from P. falciparum gene engineering:
  • Type: Recombinant vector construction
  • Description:
  • Detailed Gene Information: Click Here.
• Immunization Route: Intramuscular injection (i.m.)
• Description: Prime-boosting vaccine that use different vectors: ChAd63 ME-TRAP is the prime vaccination and MVA ME-TRAP is the booster.

Human Response

• Host Strain: Healthy men aged 18–50 years old in the peri-urban area of Dakar in Senegal, West Africa.
• Vaccination Protocol: Random, controlled, single-blinded phase IIb efficacy trial.
  Participants radomly receive either 1) ChAd63 ME-TRAP (5x105 vp) as prime vaccination and MVA ME-TRAP (2x108 pfu) as booster eight weeks later or 2) two doses of anti-rabies vaccine (0.5ml) at the same interval. (Mensah et al., 2016)
• Immune Response: Increases in anti-TRAP IgG responses.
  Cellular immunogenicity: TRAP-specific T cells induced
  14 days after prime vaccination: 261 SFC per million PBMC (95% CI 165–412) compared with 48 SFC (95% CI 30–79 SFC) in control group.
  7 days after booster: 932 SFC (95% CI 754–1152) compared with 57 SFC per million (95% CI 44–72) in control group.
  Humoral: TRAP peptide pools 1, 2, 3 and 6 frequently recognized: 66–93% positive response to these pools at the peak time point after MVA in TRAP group, comparing with 19% positive response to pool 3 and 10% positive response to pool 1 in control group. Positive correlation between humoral and cellular immunogenicity.
  Neutralising antibodies to the ChAd63 vector detected: LGMT of 216 (95% CI 188–247), 56% responses above the clinically relevant threshold of 200.(Mensah et al., 2016)
• Side Effects: ChAd63: Solicited local AEs: Mild or moderate pain, itching, redness, swelling, and warmth. Systematic AEs: fever, myalgia, discomfort, headache, arthralgia, and nausea.
  MVA: more reactogenic than ChAd63, but still tolerable for the majority. Solicited local AEs: swelling, pain, itching, and warmth (last between a few hours to 2 days). Systematic AEs: arthralgia, fever, headache, myalgia, nausea, and discomfort (Mensah et al., 2016)
• Efficacy: PCR positive cases:12 of 57 in TRAP group, 13 of 58 in controls: 8% efficacy, but not statistically significant.
  Malaria cases: 11 in TRAP group, 12 in control group: unadjusted efficacy of 9%, non-significant.
  *protocol-specified metaanalysis after pooling the data of the Kenyan and Senegalese trials showed significant protective efficacy of 50% (95% CI 17%-70%). (Mensah et al., 2016)