Researchers have discovered why the parasite that causes the deadliest form of malaria only infects humans.
The team recently showed that the interaction between a parasite protein called RH5 and a receptor called basigin was essentially required for the invasion of red blood cells by the parasite that causes the deadliest form of malaria. Now, they've discovered that this same interaction is also an important factor in explaining why the parasite seems to be remarkably specific to humans. This research will help guide eradication strategies in regions where malaria is endemic.
There are several distinct species of parasite that cause malaria. The malaria parasite species responsible for severe illness and death, Plasmodium falciparum, only infects humans, but is closely related to several species that infect chimpanzees and gorillas. Strangely, these species seem to be very specific - individual species appear to infect only humans, chimpanzees or gorillas, even when these primates live in close proximity. This striking observation piqued the curiosity of the team which prompted a search for the molecules that controls this specificity and revealed the important role of the RH5-basigin interaction.
"It's remarkable that the interaction of a single pair of proteins can explain why the most deadly form of malaria is specific to humans" says Dr Julian Rayner, from the Wellcome Trust Sanger Institute Malaria Programme. "This research will strengthen eradication strategies by ruling out great apes as possible reservoirs of human infection by P. falciparum."
The team investigated the question of host specificity by examining two important protein interactions involved in the invasion of red blood cells - the interactions between the parasite and host EBA175-Glycophorin A and RH5-basigin.
They found that the EBA175 protein from chimpanzee specific malaria parasites could bind to human Glycophorin A, thereby ruling out this interaction as a specificity factor.