A origem da malária maligna

The origin of malignant malaria

Stephen M. Richa,1, Fabian H. Leendertzb, Guang Xua, Matthew LeBretonc, Cyrille F. Djokoc,d, Makoah N. Aminaked, Eric E. Takangc, Joseph L. D. Diffoc, Brian L. Pikec, Benjamin M. Rosenthale, Pierre Formentyf, Christophe Boeschg, Francisco J. Ayalah,1 and Nathan D. Wolfec,i,1

+Author Affiliations

aLaboratory of Medical Zoology, Division of Entomology (PSIS), University of Massachusetts, Amherst, MA 01003;

bDepartment Emerging Zoonoses, Robert Koch Institute, Nordufer 20, D-13353 Berlin, Germany;

cGlobal Viral Forecasting Initiative, San Francisco, CA 94104;

dThe Biotechnology Centre, University of Yaounde I, Yaounde, Cameroon;

eAnimal Parasitic Diseases Laboratory, Agricultural Research Service, US Department of Agriculture, Beltsville, MD 20705;

fEbola Taï Forest Project, World Health Organization (WHO), WHO Office in Abidjan, Côte d'Ivoire;

gDepartment of Primatology, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany;

hDepartment of Ecology and Evolutionary Biology, University of California, Irvine, CA, 92697; and

iProgram in Human Biology, Stanford University, Stanford, CA 94305

Contributed by Francisco J. Ayala, July 13, 2009 (sent for review June 29, 2009)

Abstract

Plasmodium falciparum, the causative agent of malignant malaria, is among the most severe human infectious diseases. The closest known relative of P. falciparum is a chimpanzee parasite, Plasmodium reichenowi, of which one single isolate was previously known. The co-speciation hypothesis suggests that both parasites evolved separately from a common ancestor over the last 5–7 million years, in parallel with the divergence of their hosts, the hominin and chimpanzee lineages. Genetic analysis of eight new isolates of P. reichenowi, from wild and wild-born captive chimpanzees in Cameroon and Côte d'Ivoire, shows that P. reichenowi is a geographically widespread and genetically diverse chimpanzee parasite. The genetic lineage comprising the totality of global P. falciparum is fully included within the much broader genetic diversity of P. reichenowi. This ••• is inconsistent with the co-speciation hypothesis. Phylogenetic analysis indicates that all extant P. falciparum populations originated from P. reichenowi, likely by a single host transfer, which may have occurred as early as 2–3 million years ago, or as recently as 10,000 years ago. The evolutionary history of this relationship may be explained by two critical genetic mutations. First, inactivation of the CMAH gene in the human lineage rendered human ancestors unable to generate the sialic acid Neu5Gc from its precursor Neu5Ac, and likely made humans resistant to P. reichenowi. More recently, mutations in the dominant invasion receptor EBA 175 in the P. falciparum lineage provided the parasite with preference for the overabundant Neu5Ac precursor, accounting for its extreme human pathogenicity.

chimpanzees human evolution Plasmodium falciparum Plasmodium reichenowi zoonosis

Footnotes

1To whom correspondence may be addressed. E-mail: smrich@psis.umass.edu, ndwolfe@stanford.edu, or fjayala@uci.edu

Author contributions: S.M.R., F.H.L., and N.D.W. designed research; S.M.R., F.H.L., G.X., M.L., C.F.D., M.N.A., E.E.T., J.L.D.D., and N.D.W. performed research; F.H.L., C.B., and N.D.W. contributed new reagents/analytic tools; S.M.R., G.X., and B.M.R. analyzed data; and S.M.R., B.L.P., B.M.R., P.F., F.J.A., and N.D.W. wrote the paper.

The authors declare no conflict of interest.

Freely available online through the PNAS open access option.

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