ACKR1 and malaria: In Plasmodium vivax (Pv), the geographically most widespread human malaria parasite1, the Pv Duffy-Binding Protein (PvDBP) is a typical example of this fine balance with polymorphic antigenic domains and conserved residues within the protein region (region II, DBPII) binding to the host cell receptor, the Duffy antigen (also known as Duffy Antigen Receptor for Chemokine, DARC).