Analysis of human antibodies to erythrocyte binding antigen 175 peptide 4 of Plasmodium falciparum.

BACKGROUND The IgG1 and IgG3 antibodies are considered cytophilic and protective against Plasmodium falciparum, whereas IgG2 and IgG4 are thought to block protective mechanisms. OBJECTIVES The main objective was to measure antibodies directed against erythrocyte binding antigen-175 (EBA-175) peptide 4 and analyze the relationship between such antibodies and clinical malaria attack. METHODS Using an enzyme-linked immunosorbent assay, a retrospective analysis of naturally acquired antibodies to synthetic peptide from EBA-175 peptide 4 has been carried out in 158 school children from the village of Dienga in Gabon. RESULTS The overall prevalence rates of antibodies to EBA-175 peptide 4 were 85.2%, 66.8%, 52.6%, 71.6% and 64.0% for total IgG, IgG1, IgG2, IgG3 and IgG4, respectively. Protection from clinical malaria, determined after a prospective 1-year study, was associated with the levels of IgG and IgG1 antibodies that increased with age. CONCLUSION Together, these data suggest that age/exposure-related acquisition of anti-EBA-175 antibodies may contribute to the development of clinically protective immunity and could be taken into account in malaria control strategies when they are confirmed.