British researchers have discovered a biochemical key used by the malaria parasite to invade human blood cells. The discovery could pave the way for an effective malaria vaccine.
The Plasmodium malaria parasite has a complex life cycle, and that gives scientists different targets for trying to interrupt its development.
One critical point in that process is when the parasite enters the victim's red blood cells. It does that by interacting with a chemical receptor on the surface of the cell.
Previous research identified several of those receptors, but the problem has been that if one receptor is blocked, the parasite uses a different one. Now, scientists have identified a single blood cell receptor that Plasmodium absolutely needs to enter the blood cell.
Julian Rayner of the Wellcome Trust Sanger Institute in Cambridge says the research team used different techniques to prove the key role of the receptor, called basigin.
"And what we discovered essentially is by adding in protein or antibody in increasing amounts, we could block invasion of the red blood cell," Rayner said at a London news conference. "Our colleagues, led by Manoj Duraisingh at Harvard, used a genetic approach to create red blood cells with reduced amounts of basigin on the surface, and again that had a big impact on invasion."
In the process, Rayner says they used more than 15 varieties of the malaria parasite, including some currently circulating in the wild.
"But [basigin] seems to be used by every parasite strain that we've tested to date. And some of the ones that we've tested in this paper were in collaboration with scientists in Senegal. And these are parasites that are really freshly isolated from people's arms, so they haven't been sitting in a culture dish for a long time. These are real parasites as recently exposed to humans."
Other malaria vaccines are in development, but co-author Gavin Wright expressed confidence that one based on this discovery might be more successful.
"We've probably got more data to show that this really is a critical interaction than for any other candidate in the past. So, as a starting point for developing a vaccine, you couldn't hope for better."
The researchers say a vaccine targeting the basigin receptor may be a decade or more away. But they say that unlike vaccines for some other diseases, which are useful only in prevention, a malaria vaccine that targets basigin may also be a useful treatment, blocking the constant re-infection of blood cells that characterizes malaria.
Gavin Wright, Julian Rayner and their colleagues publish their findings in the journal Nature.