• Vaccine Name: p52(-)/p36(-) GAP
• Target Pathogen: Plasmodium spp.
• Target Disease: Malaria
• Type: Live, attenuated vaccine
• Status: Clinical trial
• Host Species for Licensed Use: Human
• Antigen: Genetically attenuated NF54 strain P.falciparum sporozoites: p52 and p36 gene deleted
• Immunization Route: mosquito bites

Human Response

• Host Strain: Four volunteers identifying as Caucasian and two as African American. (Spring et al., 2013)
• Host age: 18-42 years(Spring et al., 2013)
• Host gender: 3 males 3 females(Spring et al., 2013)
• Vaccination Protocol: Single group, non-randomized, phase I/IIa Trial.
  6 volunteers received five infectious bites from GAP-infected Anopheles mosquito at first exposure, and then received around 200 bites as second exposure one month later. (Spring et al., 2009)
• Immune Response: Humoral: Post 5 bites: below the threshold. Post 200 bites: Pre-erythrocytic stage antigens: LSA-1 still not detectable, 2.9 μg/ml (0.7–12.3 μg/ml) CSP. Blood stage antigens: Only the volunteer with a peripheral blood stage parasitemia has humoral response to MSP-1 (3D7) and MSP-1 (FVO).
  
  Cellular: IFN-γ, IL-2 and TNF responses significantly increased in the CD4 T cell compartment after 5 bites exposure, and amongst CD8 T cells after 200 bites exposure. IFN-γ production was primarily produced by CD8 T cells, and TNF production was primarily produced by CD4 T cells. No significant responses to CSP overlapping peptides or CSP recombinant protein observed.
  
  Memory responses: CSP peptide 2, CelTOS and MSP-1 recalled the highest responses, followed by CSP and LSA-1 protein and then AMA-1, the CSP peptide pool and CSP peptide 4. LSA-1 peptide pools #1 and #2 failed to recall any responses. (Spring et al., 2013)
• Side Effects: First exposure: erythema and pruritus
  Second exposure: local: erythema, pruritus, edema; systematic: fever, nausea/vomiting, headache and malaise in the first 24 hours of exposure.
  **One volunteer developed peripheral P. falciparum parasitemia on day 12 post-second, high dose exposure:24 parasites/μL, experienced fever, headache, fatigue, malaise, and myalgia. The Stopping Rule was activated and therefore the efficacy test was not executed as originally planned. (Spring et al., 2013)