Safety and Immunogenicity of EBA-175 RII-NG Malaria Vaccine Administered Intramuscularly

This study is a phase I, double-blinded, placebo-controlled, dosage-escalation study of the safety and immunogenicity of EBA-175 RII-NG malaria vaccine administered intramuscularly. The vaccine is a recombinant Plasmodium falciparum (Pf) erythrocyte-binding antigen 175 kDa Region II-nonglycosylated (EBA-175 RII-NG) adsorbed to aluminum phosphate adjuvant. The study is being conducted at Baylor College of Medicine, Houston, Texas. Eighty healthy subjects, between the ages of 18 and 40 years, males and females, will be recruited from Houston, Texas, and will participate in the study for approximately 13 months. Subjects will be randomized to receive 3 doses of the vaccine or saline placebo by the intramuscular route in a 9:1 ratio at 0, 1 and 6 months. The safety and immunogenicity of ascending dosages of the vaccine will be assessed. Eighteen subjects will receive vaccine at each of the following dosage levels: 5, 20, 80 and 160 micrograms. Two subjects will receive placebo for each dosage level. Dosage escalation will proceed only after review of the 2-week safety data of the 2 initial doses of the prior dosage level. The primary study objective is to assess the safety and reactogenicity (tolerability) of ascending dosages of EBA-175 RII-NG vaccine among healthy subjects given in 3 intramuscular doses at 0, 1 and 6 months. The secondary study objective is to evaluate the immunogenicity of the EBA-175 RII-NG vaccine by measuring anti-EBA-175 RII-NG antibodies using enzyme-linked immunosorbent assay (ELISA), anti-parasite antibodies by indirect fluorescence antibody test (IFAT), inhibition of binding of EBA-175 RII-NG to red blood cells (RBCs), and inhibition of Pf growth in vitro.