title: The origin of malignant malaria.
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 finding 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.
authors: Laboratory of Medical Zoology, Division of Entomology (PSIS), University of Massachusetts, Amherst, MA 01003, USA. smrich@psis.umass.edu
authors: Stephen M
authors: SM
authors: Rich
authors: Fabian H
authors: FH
authors: Leendertz
authors: Guang
authors: G
authors: Xu
authors: Matthew
authors: M
authors: LeBreton
authors: Cyrille F
authors: CF
authors: Djoko
authors: Makoah N
authors: MN
authors: Aminake
authors: Eric E
authors: EE
authors: Takang
authors: Joseph L D
authors: JL
authors: Diffo
authors: Brian L
authors: BL
authors: Pike
authors: Benjamin M
authors: BM
authors: Rosenthal
authors: Pierre
authors: P
authors: Formenty
authors: Christophe
authors: C
authors: Boesch
authors: Francisco J
authors: FJ
authors: Ayala
authors: Nathan D
authors: ND
authors: Wolfe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D006023:Glycoproteins / Q000235:genetics; D006801:Humans; D008288:Malaria / Q000378:metabolism / Q000469:parasitology* / Q000662:veterinary; D008969:Molecular Sequence Data; D009154:Mutation; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D002679:Pan troglodytes / Q000469:parasitology; D010802:Phylogeny; D010961:Plasmodium / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D010963:Plasmodium falciparum / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011529:Protozoan Infections, Animal / Q000378:metabolism / Q000469:parasitology; D015800:Protozoan Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D006023:Glycoproteins; D015800:Protozoan Proteins; C041595:circumsporozoite protein, Protozoan; D019158:N-Acetylneuraminic Acid