Whole-parasite malaria vaccines have shown promise in clinical trials. We recently reported the first
human trial of a malaria vaccine based on Plasmodium falciparum genetically attenuated parasites (PfGAP).
Herein we report for the first time that PfGAP induces prolonged functional humoral responses in humans.
Six volunteers were exposed to 5 bites of PfGAP-infected mosquitoes followed by approximately 200
bites. Plasma collected from all volunteers 3 months after the last exposure efficiently inhibits invasion
of hepatocytes by P. falciparum sporozoites. The level of inhibition observed is comparable to that attained
using plasma collected after 4–5 intravenously administrations of high numbers of irradiated sporozoites,
validating the potential of PfGAP malaria vaccines. Our data highlight the role of antibody responses in
pre-erythrocytic stages of human malaria, and suggests that to be protective, malaria vaccines might
need to elicit long-lasting functional antibodies in addition to cellular responses.