The malarial parasites found in African tree-dwelling rats has been found to share a close evolutionary relationship with Plasmodium falciparum, the deadly form of malaria for humans and Plasmodium reichenowi in chimpanzees. Based on the result of a novel study from the Sackler Institute for Comparative Genomics at the American Museum of Natural History.
"This is the first time that a relationship has been found between human and rodent malaria," said Susan Perkins, Assistant Curator of Invertebrate Zoology at the Museum.
"In all past studies, P. falciparum seemed not to be closely related to anything else but the chimpanzee parasite. But this study places it in a sister group of parasites from rodents," she added.
During the study, the researchers amplified the entire mitochondrial genome of malarial parasites in a single piece via polymerase chain reaction (PCR) and then sequence it to reconstruct the whole genome.
They found that the malarial parasites found in African thicket rats, P. chabaudi, P. berghei, and P. yoelii, as a sister group of human and chimpanzee P. falciparum, and P. reichenowi,.
This is interesting and surprising because the parasite found in African thicket rats-the only malarial parasite to be discovered first in mosquitoes and only later in a vertebrate host-is the most common laboratory model for human malarial research.
The P. falciparum-rodent group is most closely related to malarial parasites that infect humans and primates in Asia and other primates in Africa.
"The link between human malaria and rodent malaria is exciting because, if they really are that closely related, our laboratory models might be more powerful for helping to study how to fight the disease," said Perkins.
She also believes that this link may include more than these species: as-yet unpublished data collected earlier in her lab found a closely related form of, Plasmodium, in bats from the same area, and it may be that the most virulent form of malaria jumped into humans from these other arboreal animals.
The new paper is published in the early online edition of Mitochondrial DNA.