Genome sequencing of chimpanzee malaria parasites reveals possible pathways of adaptation to human hosts

Plasmodium falciparum causes most human malaria deaths, having prehistorically evolved from parasites of African Great Apes. Here we explore the genomic basis of P. falciparum adaptation to human hosts by fully sequencing the genome of the closely related chimpanzee parasite species P. reichenowi, and obtaining partial sequence data from a more distantly related chimpanzee parasite (P. gaboni). The close relationship between P. reichenowi and P. falciparum is emphasized by almost complete conservation of genomic synteny, but against this strikingly conserved background we observe major differences at loci involved in erythrocyte invasion. The organization of most virulence-associated multigene families, including the hypervariable var genes, is broadly conserved, but P. falciparum has a smaller subset of rif and stevor genes whose products are expressed on the infected erythrocyte surface. Genome-wide analysis identifies other loci under recent positive selection, but a limited number of changes at the host–parasite interface may have mediated host switching. Plasmodium falciparum, known to cause malaria in humans, evolved from parasites of African Great Apes. Here, the authors compare the genome of the human parasite, P. falciparum, with those of two related chimpanzee parasites, P. reichenowi and P. gaboni, and provide insight into the genetic basis of P. falciparumadaptation to human hosts.