Variants ofPlasmodium falciparumErythrocyte Membrane Protein 1 Expressed by Different Placental Parasites are Closely Related and Adhere to Chondroitin Sulfate A

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 g sequence class) from laboratory-adapted strains is thought to be responsible for binding to CSA. In this study, DBL-g 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-g domain with CSA binding capacities. Furthermore, sequence analysis data provide evidence for antigenic conservation among the DBL-g 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. Plasmodium falciparum is the most important malaria parasite, causing 11 million deaths per year. Malaria during pregnancy remains a serious problem, and the effects of placental infections on both fetus and mother are considerable. P. falciparum‐infected erythrocytes (IEs) adhere to syncytiotrophoblast cells of the placenta via the glycosaminoglycan chondroitin sulfate A (CSA), which is linked to the proteoglycan thrombomodulin. Parasites that infect the placenta bind CSA preferentially, whereas most parasites found in a nonpregnant host bind CD36 [1].