Figure 2

Effect of CPS-induced IgG on in vitro hepatocyte traversal. (A) The proportion of traversed (wounded) cells was determined by flow cytometric analysis, after gating out debris and doublets. Sporozoites with dextran only were used as a positive control and sporozoites pre-treated with cytochalasin D (cytoD) and dextran, as a negative control. Cells incubated with dextran only were used to correct for background. (B) Sporozoites were pre-incubated with 10 mg/ml pre- or post-immunization IgG from three pools of two volunteers each (Study 1) or (C) from six individual volunteers (Study 2), all of which underwent ChemoProphylaxis and Sporozoites immunization (CPS). Samples were tested in 4 experiments with 3 mosquito batches, in duplicate or triplicates. (D) The percentage inhibition of traversal was calculated for post- compared to pre-immunization IgG for each pool/volunteer at a concentration of either 1 or 10 mg/ml. Data are shown as the mean of duplicate or triplicate measurements, and presented as circles or squares for Study 1 and 2, respectively. Filled symbols show volunteers protected against mosquito challenge. Open symbols represent volunteers with unknown protection status regarding mosquito challenge (blood-stage challenged). Differences between pre- and post-immunization IgG, and 1 and 10 mg/ml IgG was tested using the paired Student’s t-test.