Fig 1.
a Vaccination was discontinued in one subject due to blood phobia. b One subject was excluded from further vaccinations due to severe anemia. c One subject migrated out of the country without prior notification. d One subject voluntarily withdrew to relocate to another town. e One subject discontinued the study and was lost to follow up for safety evaluation after receiving all three vaccinations. All attempts to find this subject failed. Abbreviation: EBA-175 RII-NG–Erythrocyte binding antigen 175 region II non-glycosylated.
Table 1.
Demographic and baseline characteristics by dose of study population.
Table 2.
Adverse events by severity vaccine dose and frequency of vaccinations.
Fig 2.
Observed laboratory adverse events for all dose escalation groups.
Panel A is for screening prior to enrolment; Panels B and C are for vaccination 1, Day 0 and Day 14 respectively; Panels D and E are for vaccination 2, Day 0 and Day 14 respectively and Panels F, G and H are for vaccination 3, Day 0, Day 14 and Day 28 respectively. Abbreviations: ALT—Alanine Transaminase; AST—Alanine Aminotransferase; CR–Creatinine; BG–Blood glucose; K–Potassium; Na–Sodium; Hb–Hemoglobin; PLT–Platelets; WBC–White Blood Cells.
Fig 3.
Anti-EBA-175 RII-NG IgG antibody levels (ELISA units) and growth inhibition activity against P. falciparum 3D7 parasite.
Panel A: Geometric mean IgG antibody levels (ELISA units) to the vaccine antigen EBA-175 RII-NG measured in each treatment group on different days (D0 to D194) post vaccination. Panel B: The left y-axis represents mean percentage P. falciparum 3D7 parasite growth inhibition measured for each treatment group on the different days post vaccination plotted as vertical bars. The right y-axis represents mean EBA175 ELISA units (on log 10 scale) used per growth inhibition assay well for each treatment group on the different days post vaccination plotted as lines. One subject in the placebo group recorded the highest anti-EBA-175 RII-NG IgG levels at baseline which persisted throughout the study. Both the high mean EBA 175 ELISA units/GIA well and mean GIA values observed in the placebo group were largely due to this subject. One ELISA unit is the reciprocal of the dilution required to give an optical density = 1 in the standardized assay. Any data point less than the minimal detectable level was assigned as 5 ELISA units in the growth inhibition assay well in the analysis. Vaccinations occurred on Days 0, 28 and 180. Blood samples were drawn for immunogenicity prior to vaccination. Abbreviations: EBA-175 RII-NG–Erythrocyte binding antigen 175 region II non-glycosylated; IgG–Immunoglobulin G; GIA–Growth inhibition assay.
Table 3.
Proportion of subjects with 4-fold increase from baseline in anti-EBA175 antibody response.