Carbohydrates on the surface of malaria parasites play a critical role in their ability to infect mosquito and human hosts. This discovery, published last week in Nature Communications, may someday lead to improvements in the only malaria vaccine approved to protect against the most deadly malaria species, Plasmodium falciparum.
The research team consisted of scientists from the Walter and Eliza Hall Institute, with support from a professor at University of Alberta, Canada. Together, they showed that the malaria parasite ‘tags’ its proteins with carbohydrates in order to stabilize and transport them. This ‘tagging’ is important for two stages malaria lifecycle—the early stages of human infection where the parasite invades the liver and later when it is transmitted back to a mosquito host.
If the parasite’s ability to attach these carbohydrates to its proteins is compromised, infection and transmission are hindered and the parasite becomes too weak to survive in the host.
"Carbohydrates have long been considered unimportant to malaria parasites. This discovery reveals that carbohydrates are very important, and in two completely different lifecycle stages. This is exciting because to ultimately eradicate malaria we need combined approaches that attack different stages of the parasite at once," explained Justin Boddey, Ph.D., one of the lead researchers of the study.
The researchers hope these findings will spur improvements to RTS,S/AS01, the first malaria vaccine approved for human use. Although it has been in use since July 2015, its efficacy has not been as robust as originally hoped.
This vaccine uses a protein that is easily recognized by the immune system and mimics one of the malaria proteins used in the current study. It’s possible that attaching a carbohydrate to this protein could improve its efficacy as a vaccine, as similar changes to other vaccines have been successful in the past.
Image: A malaria parasite (yellow) invading liver cells (pink/red). Image courtesy of WEHI.TV/Walter and Eliza Hall Institute of Medical Research.