Longitudinal analysis of naturally acquired PfEMP1 CIDR domain variant antibodies identifies associations with malaria protection

BACKGROUND. Malaria pathogenicity is determined, in part, by the adherence of Plasmodium falciparum-infected erythrocytes to the microvasculature mediated via specific interactions between P. falciparum erythrocyte membrane protein (PfEMP1) variant domains and host endothelial receptors. Naturally acquired antibodies against specific PfEMP1 variants can play an important role in clinical protection against malaria. METHODS. We evaluated IgG responses against a repertoire of PfEMP1 CIDR domain variants to determine the rate and order of variant-specific antibody acquisition and their association with protection against febrile malaria in a prospective cohort study conducted in an area of intense, seasonal malaria transmission. RESULTS. Using longitudinal data, we found that IgG antibodies against the pathogenic domain variants CIDR alpha 1.7 and CIDR alpha 1.8 were acquired the earliest. Furthermore, IgG antibodies against CIDR gamma 3 were associated with reduced prospective risk of febrile malaria and recurrent malaria episodes. CONCLUSION. This study provides evidence that acquisition of IgG antibodies against PfEMP1 variants is ordered and demonstrates that antibodies against CIDR alpha 1 domains are acquired the earliest in children residing in an area of intense, seasonal malaria transmission. Future studies will need to validate these findings in other transmission settings and determine the functional activity of these naturally acquired CIDR variant-specific antibodies. TRIAL REGISTRATION. ClinicalTrials.gov NCT01322581. FUNDING. Division of Intramural Research, National Institute of Allergy and Infectious Diseases, NIH.