Studying the body's immune response to malaria infection could help scientists find life-saving vaccines

January 4, 2017

Three malaria proteins that trigger an immune response in infected individuals have been identified by A*STAR researchers. These proteins could underpin a new vaccine against the world's deadliest parasitic disease.

Half a million people, mostly young children, are killed by annually. Despite almost a century of research and development, no commercial vaccine exists for malaria.

Part of the problem is the complexity of the parasite, says Laurent Rénia, who led the study at the A*STAR Singapore Immunology Network. Compared with viruses, which have a maximum of 50 genes, the malaria parasite has 5,000 genes and 14 chromosomes. It also changes shape, reinventing itself as it moves from humans or monkeys to mosquitoes and back to the mammalian host. "Everything that works for viruses, doesn't work for malaria," says Rénia. "We need to think differently."

To start with, researchers need to be less haphazard in selecting potential vaccine targets. "Vaccine studies to date have been conducted like witchcraft, with no clear criteria for deciding why one protein candidate is better than another," says Rénia. "We are trying to put a bit of rationality into the process."

In 2009, Rénia and a team of researchers in the Netherlands discovered that individuals exposed to a few bites from infected mosquitos, while taking the antimalarial drug chloroquine, developed long-lasting immunity. Rénia wanted to determine the specific parasitic proteins that trigger this . These antigens, he reasoned, could offer a legitimate target for potential vaccines.

He collaborated with an international team to engineer mammalian that express a range of malarial antigens on their surfaces. The team exposed the cells to blood samples taken from two groups of a total of 14 individuals: those who had been treated for long-lasting immunity, and those who had not. The immunized individuals produced antibodies that recognized three malaria antigens, which were generally absent in the non-immunized group.

The researchers then tested these antigens' potential as vaccine targets. They introduced one of the antigens to human liver cells growing in a dish, then exposed the cells to rabbit antibodies that recognize and block the protein's activity. The antibodies protected the liver cells against parasitic invasion.

During an infection, the first incubates and amplifies in the liver, before flooding the bloodstream and attacking . Blocking the infection at this early stage could save lives.

Rénia now wants to replicate the experiment on a larger group to see if the same three proteins resurface as provokers of an immune response.

Explore further: Why some people may not respond to the malaria vaccine

More information: Kaitian Peng et al. Breadth of humoral response and antigenic targets of sporozoite-inhibitory antibodies associated with sterile protection induced by controlled human malaria infection, Cellular Microbiology (2016). DOI: 10.1111/cmi.12608

Related Stories

Why some people may not respond to the malaria vaccine

December 20, 2016

Generating protective immunity against the early liver stage of malaria infection is feasible but has been difficult to achieve in regions with high rates of malaria infection. Researchers at the University of Washington ...

Improving human immunity to malaria

August 1, 2012

The deadliest form of malaria is caused the protozoan Plasmodium falciparum. During its life-cycle in human blood, the parasite P. falciparum expresses unique proteins on the surface on infected blood cells.

Discovery finds possible new route to malaria vaccine

December 28, 2015

Oxford University researchers across the globe are working to beat Malaria. Now, a team of Oxford scientists in the UK and Kenya, working with colleagues in three Swiss institutes, have found two people who could reveal a ...

Recommended for you

Antibody for fighting cancer emerges

May 19, 2017

While studying the underpinnings of multiple sclerosis, investigators at Brigham and Women's Hospital came across important clues for how to treat a very different disease: cancer. In a paper published in Science Immunology, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.