TABLE 4.

P. falciparum-specific IFN-γ responses induced by a multiple DNA vaccine and enhanced by exposure to sporozoite-infected mosquitoes

CohorthGM-CSF (μg/dose)Volunteers with positive IFN-γ responses before challengeVolunteers with evidence of boosting of IFN-γ responses after challenge
1 wk before challenge4 wks after challengeb9 wks after challengeb
VaccineesControlsVaccineesControlsVaccineesControls
106/8a0/37/81/34/81/3
2204/80/38/81/34/80/3
31002/71/32/71/33/71/3
45003/80/46/80/44/80/4
Total15/31 (48.4%)1/13 (7.7%)23/31 (74.2%)3/13 (23.1%)15/31 (48.4%)2/13 (15.4%)
P valuec0.010.0020.04
  • a No. responders/no. tested

  • b IFN-γ responses were considered to be boosted by parasite challenge only if the number of IFN-γ SFCs/1 × 106 PBMCs was at least two times higher after challenge than before challenge.

  • c Comparison of vaccinees and controls in each challenge group (1, 4, or 9 weeks).