Carbohydrates could be key to improved malaria vaccine

Offering vital clues to improving malaria vaccine, an international research team has shown that carbohydrates on the surface of malaria parasites play a critical role in their ability to infect mosquito and human hosts.

The discovery, published in the journal Nature Communications, also suggests steps that may improve the only malaria vaccine approved to protect people against Plasmodium falciparum malaria -- the most deadly form of the disease.

The team had shown that the malaria parasite "tags" its proteins with carbohydrates in order to stabilise and transport them and that this process was crucial to completing the parasite's life cycle.

"Interfering with the parasite's ability to attach these carbohydrates to its proteins hinders liver infection and transmission to the mosquito and weakens the parasite to the point that it cannot survive in the host," said Justin Boddey from Walter and Eliza Hall Institute in Parkville, Victoria, Australia.

Malaria infects over 200 million people worldwide each year and kills around 650,000 people, predominantly pregnant women and children. Efforts to eradicate malaria require the development of new therapeutics, particularly an effective malaria vaccine.

The first malaria vaccine approved for human use -- RTS,S/AS01 -- got the nod of the European regulators in July 2015 but has not been as successful as hoped with marginal efficacy that wanes over time.

The new research is aimed at improving malaria vaccine design. "The protein used in the RTS, S vaccine mimics one of the proteins we've been studying on the surface of the malaria parasite that is readily recognised by the immune system," Ethan Goddard-Borger from Walter and Eliza Hall Institute said.

"With this study, we've shown that the parasite protein is tagged with carbohydrates, making it slightly different to the vaccine, so the antibodies produced may not be optimal for recognising target parasites."

"It may be that a version of RTS, S with added carbohydrates will perform better than the current vaccine," he said, adding that there were many documented cases where attaching carbohydrates to a protein improved its efficacy as a vaccine.