Résumé
Plasmodium falciparum is the major human malaria agent responsible for 200
to 300 million infections and one to three million deaths annually, mainly
among African infants. The origin and evolution of this pathogen within
the human lineage is still unresolved. A single species, P. reichenowi,
which infects chimpanzees, is known to be a close sister lineage of P.
falciparum. Here we report the discovery of a new Plasmodium species
infecting Hominids. This new species has been isolated in two chimpanzees
(Pan troglodytes) kept as pets by villagers in Gabon (Africa). Analysis of
its complete mitochondrial genome (5529 nucleotides including Cyt b, Cox I
and Cox III genes) reveals an older divergence of this lineage from the
clade that includes P. falciparum and P. reichenowi (approximately 21+/-9
Myrs ago using Bayesian methods and considering that the divergence
between P. falciparum and P. reichenowi occurred 4 to 7 million years ago
as generally considered in the literature). This time frame would be
congruent with the radiation of hominoids, suggesting that this Plasmodium
lineage might have been present in early hominoids and that they may both
have experienced a simultaneous diversification. Investigation of the
nuclear genome of this new species will further the understanding of the
genetic adaptations of P. falciparum to humans. The risk of transfer and
emergence of this new species in humans must be now seriously considered
given that it was found in two chimpanzees living in contact with humans
and its close relatedness to the most virulent agent of malaria.