Safety and Immunogenicity of a Recombinant Nonglycosylated Erythrocyte Binding Antigen 175 Region II Malaria Vaccine in Healthy Adults Living in an Area Where Malaria is Not Endemic
Year of Publication
El Sahly, H; Patel, S; Atmar, R; Lanford, T; Dube, T; Thompson, D; Sim, BK; Long, C; Keitel, W
Clinical and Vaccine Immunology
Adjuvants-Immunologic; Adolescent; Adult; Aluminum Compounds; Antibodies- Protozoan; Antigens-Protozoan; Enzyme-Linked Immunosorbent Assay; Female; Human Experimentation; Immunization-Secondary; malaria; Malaria-Falciparum; Male; Phosphates; Vaccines
Erythrocyte binding antigen region II (EBA-175) is a conserved antigen of Plasmodium falciparum that is involved in binding of the parasite to the host's erythrocytes. We evaluated the safety and immunogenicity of a recombinant EBA-175 vaccine with aluminum phosphate adjuvant in healthy young adults living in the United States. Eighteen subjects/group received ascending doses (5, 20, 80, or 160 μg) of the vaccine at 0, 1, and 6 months; 8 subjects received placebo. Most of the injection site and systemic reactions were mild to moderate in intensity. After 2 or 3 doses of the vaccine at any concentration, antibody levels measured by enzyme-linked immunosorbent assay were significantly higher than those for the placebo group. Sera from subjects who received 3 doses of the vaccine at any concentration inhibited the growth of erythrocyte-stage P. falciparum at low levels compared to sera from placebo recipients or preimmune sera. In conclusion, the EBA-175 vaccine with adjuvant was safe and immunogenic in malaria-naïve subjects.