Fya/Fyb antigen polymorphism in human erythrocyte Duffy antigen affects susceptibility to Plasmodium vivax malaria
2011
King, Christopher L. | Adams, John H. | Xianli, Jia | Grimberg, Brian T. | McHenry, Amy M. | Greenberg, Lior J. | Siddiqui, Asim | Howes, Rosalind E. | da Silva-Nunes, Monica | Ferreira, Marcelo U. | Zimmerman, Peter A.
Plasmodium vivax (Pv) is a major cause of human malaria and is increasing in public health importance compared with falciparum malaria. Pv is unique among human malarias in that invasion of erythrocytes is almost solely dependent on the red cell's surface receptor, known as the Duffy blood-group antigen (Fy). Fy is an important minor blood-group antigen that has two immunologically distinct alleles, referred to as Fya or Fyb, resulting from a single-point mutation. This mutation occurs within the binding domain of the parasite's red cell invasion ligand. Whether this polymorphism affects susceptibility to clinical vivax malaria is unknown. Here we show that Fya, compared with Fyb, significantly diminishes binding of Pv Duffy binding protein (PvDBP) at the erythrocyte surface, and is associated with a reduced risk of clinical Pv in humans. Erythrocytes expressing Fya had 41–50% lower binding compared with Fyb cells and showed an increased ability of naturally occurring or artificially induced antibodies to block binding of PvDBP to their surface. Individuals with the Fya+b– phenotype demonstrated a 30–80% reduced risk of clinical vivax, but not falciparum malaria in a prospective cohort study in the Brazilian Amazon. The Fya+b– phenotype, predominant in Southeast Asian and many American populations, would confer a selective advantage against vivax malaria. Our results also suggest that efficacy of a PvDBP-based vaccine may differ among populations with different Fy phenotypes.
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