Thousands died and more than 13 million people fell ill with malaria caused by the parasite Plasmodium vivax last year. There is no vaccine for the disease, partly because multiple strains of P. vivax circulate globally, making it difficult to develop a vaccine. Now, researchers studying a protein crucial for the parasite’s survival have found two portions of that protein that do not vary across many strains. Antibodies against these portions of the protein protect against disease, according to researchers at Washington University School of Medicine in St. Louis. The study is available online in the Proceedings of the National Academy of Sciences.
“This protein – called Duffy binding protein – is the most promising target for vaccine development because it is almost impossible for the parasite to cause infection without it,” said Niraj Tolia, associate professor of molecular microbiology and the study’s senior author.
If the parasite does not bind to the human protein – either because antibodies block the binding site or because the human protein is missing – the parasite is unable to cause disease. P. vivax is found all over the world, but it causes relatively little disease in Africa, where many people lack this specific protein on their red blood cells.
Tolia and colleagues studied three antibodies that are known to prevent a range of binding proteins from latching on to the human protein, and identified the portion of the binding protein to which the antibodies were bound. Two antibodies bound to the same portion, or epitope, while the third bound at another spot. “Our study helps define what we should be targeting to get universal protection,” Tolia said.