PHILADELPHIA - Malaria parasites infecting humans and great apes share genes that allow them to hide from the host’s immune system, adhere to tissues, and cause disease. This unexpected finding changes researcher’s understanding of malaria virulence and provides potentially new targets for drugs and vaccines.
The study, based on samples collected and analyzed by researchers at the Perelman School of Medicine at the University of Pennsylvania, was led by colleagues at the Harvard School of Public Health, and published online in Nature Communications.
Malaria kills more than 500,000 people a year, mostly children in Sub-Saharan Africa. Symptoms, including severe anemia, pregnancy-associated malaria, and cerebral malaria, have been linked to the parasite’s ability to cause infected red blood cells to bind to the inner lining of blood vessels. This ability of the infected cells to adhere in this way—which is key to malaria’s virulence—is mediated by proteins expressed from var genes.
By looking at hundreds of var gene sequence fragments from DNA retrieved from fecal samples collected from wild and sanctuary apes by the team of Beatrice Hahn, MD at Penn, the group discovered that short segments of these genes are shared between malaria parasites infecting humans, chimpanzees and gorillas. Hahn, who is a professor of Medicine and Microbiology, and her team, including MD/PhD student Sesh Sundararaman, sequenced the genome of divergent chimpanzee parasites, which among other approaches, allowed them to find the conserved structure of the var genes.
Finding var segments in ape parasites indicates that they are not a recent adaptation of human malaria, but reflect a common and ancient biology. This implies that the origin of malaria virulence is much older than previously thought.
Additional details are available in the full Harvard School of Public Health news release.
Funding for the study came from the National Institutes of Health (R21 GM100207, R01 AI091595, R37 AI050529, R01 AI058715, T32 AI007532 and P30 AI045008) and the Wellcome Trust (#090851).
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