Résumé
Infected erythrocytes that sequester in the placenta via parasite-encoded VAR2CSA-type PfEMP1 are selectively eliminated following delivery as their cognate adhesion receptor in the placenta is lost.
Parasitemia among pregnant women with protective immunity to Plasmodium falciparum malaria is often dominated by VAR2CSA-positive infected erythrocytes (IEs). VAR2CSA mediates sequestration of IEs in the placenta. We hypothesized that the previously observed spontaneous postpartum clearance of parasitemia in such women is related to the expulsion of the placenta, which removes the sequestration focus of VAR2CSA-positive IEs. We assessed parasitemias and gene transcription before and shortly after delivery in 17 Ghanaian women. The precipitous decline in parasitemia postpartum was accompanied by selective reduction in transcription of the gene encoding VAR2CSA. Our findings provide a mechanistic explanation for the earlier observation.