The malaria-causing parasite Plasmodium falciparum, which is transmitted by mosquito bite, replicates in human red blood cells, which then burst causing life-threatening fever. Infected red blood cells display parasite proteins on their surface that help the parasite to survive in their human host and cause disease complications.
People who have grown up in regions where malaria is endemic usually develop protective antibodies to these parasite proteins, and symptoms in adults are mild compared with the severe disease seen in young children with no previous exposure. Previous work has indicated that the parasites causing severe disease express a set of proteins that are distinct from those produced by parasites that infect adults. But up to this point, no one had identified any of these proteins.
The authors developed a new method to compare for the first time the proteins that are expressed by two types of P. falciparum that cause severe childhood malaria and less severe adult infection, respectively. They identified one protein that is expressed on the surface of red blood cells during severe childhood malaria but not during adult infections. This protein causes infected red blood cells to stick inside blood vessels, preventing their removal in the spleen.
The study also found that this protein, unlike similar malaria proteins studied, does not vary between malaria parasites from East and West Africa, making it an ideal candidate for a universal vaccine to boost immunity to severe malaria in young children.