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Edited by Thomas E. Wellems, National Institutes of Health, Bethesda, MD, and approved February 22, 2010 (received for review October 29, 2009)
↵1D.M. and C. Barnadas contributed equally to this work.
Abstract
Malaria therapy, experimental, and epidemiological studies have shown that erythrocyte Duffy blood group-negative people, largely of African ancestry, are resistant to erythrocyte Plasmodium vivax infection. These findings established a paradigm that the Duffy antigen is required for P. vivax erythrocyte invasion. P. vivax is endemic in Madagascar, where admixture of Duffy-negative and Duffy-positive populations of diverse ethnic backgrounds has occurred over 2 millennia. There, we investigated susceptibility to P. vivax blood-stage infection and disease in association with Duffy blood group polymorphism. Duffy blood group genotyping identified 72% Duffy-negative individuals (FY*BES/*BES) in community surveys conducted at eight sentinel sites. Flow cytometry and adsorption–elution results confirmed the absence of Duffy antigen expression on Duffy-negative erythrocytes. P. vivax PCR positivity was observed in 8.8% (42/476) of asymptomatic Duffy-negative people. Clinical vivax malaria was identified in Duffy-negative subjects with nine P. vivax monoinfections and eight mixed Plasmodium species infections that included P. vivax (4.9 and 4.4% of 183 participants, respectively). Microscopy examination of blood smears confirmed blood-stage development of P. vivax, including gametocytes. Genotyping of polymorphic surface and microsatellite markers suggested that multiple P. vivax strains were infecting Duffy-negative people. In Madagascar, P. vivax has broken through its dependence on the Duffy antigen for establishing human blood-stage infection and disease. Further studies are necessary to identify the parasite and host molecules that enable this Duffy-independent P. vivax invasion of human erythrocytes.
Footnotes
- 2To whom correspondence may be addressed. E-mail: dmenard{at}pasteur.fr, omp{at}pasteur.fr, or paz{at}case.edu.
Author contributions: D.M., C. Barnadas, A.R., C.L.K., O.M.-P., and P.A.Z. designed research; D.M., C. Barnadas, C. Bouchier, C.H.-H., L.R.G., A.R., V.T., J.-F.C., O.D., O.B., J.P., and B.T.G. performed research; C.H.-H., Y.C., C.L.K., and P.A.Z. contributed new reagents/analytic tools; D.M., C. Barnadas, C.H.-H., Y.C., O.B., C.L.K., O.M.-P., and P.A.Z. analyzed data; and D.M., C. Barnadas, Y.C., C.L.K., O.M.-P., and P.A.Z. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession nos. GU130196 and GU130197).
This article contains supporting information online at www.pnas.org/cgi/content/full/0912496107/DCSupplemental.
Plasmodium vivax clinical malaria is commonly observed in Duffy-negative Malagasy people
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