New Malaria Access Into Human Cells Found

Scientists from The Walter and Eliza Hall Institute in Melbourne in Australia, have identified the newest pathway taken by the malaria parasites to infect the body's red blood cells, and have made another step towards an effective vaccine for the disease.

Malaria is the disease that infects 400 million people ever year, out of which over one million, mostly children, die, so before finding a vaccine and a cure, the researchers' job is never over.

The most severe form of malaria is caused by the Plasmodium falciparum parasite and part of its success is that it always find a way of penetrating red blood cells.

Malaria parasites use proteins called glycophorins as a way of entering the red blood cells, and this is known by scientists for decades now, but apparently there was also an alternative pathway, wich does not involve glycophorins.

This new method needs the binding of the parasite molecule called PfRh4 to Complement Receptor 1 (CR1), which is a common protein found on the surface of red blood cells.

Professor Alan Cowman, head of the institute's Infection and Immunity division, and leader of the research said that “ the parasite is like a master burglar – it will try a variety of different methods to get into the house, not just the front door, and although the human body has evolved a variety of methods to keep the parasite out, it keeps finding new ways to get in.”

The key is that the PfRh family of surface proteins is the one that recognizes red blood cell receptors, thus allowing the parasite to attach to their surface and get in.

“We think that the parasite uses this protein to correctly identify the red blood cell and say 'Yes, this is the one we want to invade', it's like a quality assurance process,” said Professor Cowman.

“The PfRh4-CR1 pathway is one of the most important of the pathways we've identified for entry of malaria parasites into cells, and we are now at the stage where we have identified the best combination of proteins for a vaccine, and are ready to start clinical development,” added the Professor.

Once both the glycophorin and the CR1 pathways are blocked, the parasite's infection decreases by 90%.

“These results suggest that if a vaccine were to stimulate the immune system to recognize and generate antibodies to the prevalent invasion pathways, there is a good chance it would lead to a significant decrease in malaria infection,” Cowman added.

The Professor worked on this research with Dr Wai-Hong Tham, Dr Danny Wilson, Mr Sash Lopaticki, Mr Jason Corbin, Dr Dave Richard, Dr James Beeson from the institute and collaborators at the University of Edinburgh.