A team of international genetic detectives led by renowned Fogarty grantee Dr. Nathan Wolfe has determined that the malaria parasite that kills more than 1 million people a year originated from a chimpanzee parasite and did not, as was previously believed, co-evolve as the human and chimpanzee lineages split from a common ancestor.
Photo courtesy of Global Viral Forecasting Initiative
The groundbreaking analysis was made possible by the team's identification of eight new isolates of the parasite, Plasmodium reichenowi, which infects chimpanzees.
The new genetic materials came from 84 wild or wild-born captive chimps in Cameroon and Côte d'Ivoire.
The researchers, writing in Proceedings of the National Academy of Sciences, were able to conclude that the deadly human parasite, Plasmodium falciparum, is a fairly recent descendent of the more genetically diverse and thus, older chimpanzee parasite.
Previous studies, which strongly suggested the two parasites had developed independently, one in humans and one in chimps from a common ancestor millions of years ago, had been based on only a single isolate of the chimpanzee parasite.
Instead, "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 authors wrote.
Part of Wolfe's work in collecting the specimens was supported by a Fogarty International Research Scientist Development Award.
Stephen M. Rich, Fabian H. Leendertz, Guang Xu, Matthew LeBreton, Cyrille F. Djoko, Makoah N. Aminake, Eric E. Takang, Joseph L. D. Diffo, Brian L. Pike, Benjamin M. Rosenthal, Pierre Formenty, Christophe Boesch, Francisco J. Ayala and Nathan D. Wolfe. "The origin of malignant malaria." PNAS 2009 106:14902-14907; published online before print August 3, 2009.