Table 2

Phenotype of Wild-Type and Recombinant P. berghei Sporozoites

Parasite populationNo. sporozoites/infected mosquitoTypical glidingPrep. period of infection in ratsNo. EEF in HepG2 cells
MGHEMSGHEMSGHEMSGHEMSG
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WT17,0001,00019,00021825.2310260
INCO20,00090016,00017725321310
TΔS19,000ND4000000
TΔL23,000ND1,0000000
TMIC18,000ND17,000ND75ND323290
TRYP20,0004,0002,0000000
ACID21,0004,5008000000
  • Mosquitoes were dissected at days 14–18 after feeding, and sporozoites in the midguts (MG), the hemolymph (HEM), or associated with the salivary glands (SG) of mosquitoes were counted (average from at least 200 mosquitoes in three independent feeding experiments). To assess gliding motility, sporozoites were kept 2 h in 3% BSA at 4°C and allowed to glide on uncoated microscope slides. Sporozoite infectivity to rats was assessed by injecting 15,000 HEM or SG sporozoites into Sprague-Dawley rats and measuring the prepatent (prep.) period of infection; i.e., the number of days between injection and detection of erythrocytic stages of the parasite (average from six experiments; —, no infection). Sporozoite invasion was assessed by incubating 15,000 HEM or SG sporozoites with HepG2 cells for 2 h, and counting EEF 40 h later (average from four experiments).