Gene and genome evolution in malaria parasites (Plasmodium species)

Within the last five years, we have discovered evidence of multiple Plasmodium parasites infecting African apes (chimpanzees and gorillas) that are closely related to species infecting humans. In particular, we have found evidence for six species within the Laverania subgenus that includes Plasmodium falciparum, the major cause of malignant malaria in humans: three of these species exclusively infect chimpanzees, while three more exclusively infect gorillas (1).

P. falciparum originated when one of the parasite species infecting gorillas adapted to infect humans (1). The other common form of human malaria parasite is Plasmodium vivax, which is thought to be absent from humans in central Africa because they carry a Duffy-negative mutation that confers resistance to P. vivax infection. However, we have found that P. vivax is widespread among chimpanzees and gorillas across central Africa (2). Our general aim is now to investigate the evolution of these parasites, in an attempt to understand what determines their host specificity and how they have adapted to infecting different hosts (3).

Our work in this area is part of a long-running collaboration with Professor Beatrice Hahn (University of Pennsylvania). Members of the Hahn laboratory are currently generating multiple genome sequences for various of these ape parasites. This project will involve bioinformatics analyses of gene and genome sequences derived from these various Plasmodium species, to investigate their evolution.

We expect to compare multiple genome sequences from each species. Questions to be addressed include the extent of adaptive evolution in general, and the nature of host-adaptation in particular. Genes involved in parasite-host interactions will be specifically investigated, but various aspects of genome evolution will also be considered.