Variants of Plasmodium falciparum erythrocyte membrane protein 1 expressed by different placental parasites are closely related and adhere to chondroitin sulfate A

Abstract

Plasmodium falciparum-infected erythrocytes adhere to syncytiotrophoblast cells lining the placenta via glycosaminoglycans, such as chondroitin sulfate A (CSA) and hyaluronic acid. Adherence of infected erythrocytes to host receptors is mediated by P. falciparum erythrocyte membrane protein-1 (PfEMP-1). A single PfEMP-1 domain (duffy binding-like [DBL]-3, of the γ sequence class) from laboratory-adapted strains is thought to be responsible for binding to CSA. In this study, DBL-γ domains expressed by placental P. falciparum isolates were shown to have an affinity to CSA. All parasite populations accumulating in infected placentas express only 1 variant of PfEMP-1, each of which contains a DBL-γ domain with CSA binding capacities. Furthermore, sequence analysis data provide evidence for antigenic conservation among the DBL-γ sequences expressed by different placental parasites. This study offers a close reflection of the process of parasite adhesion in the placenta and is crucial to the understanding of the pathogenesis of malaria during pregnancy.