NOV 13, 2019 3:56 PM PST

A Major Step Toward a Vaccine for Severe Malaria

WRITTEN BY: Carmen Leitch

The World Health Organization estimates that there were about 219 million cases of malaria in 2017, which caused around 435,000 deaths. Scientists have now learned more about malaria proteins and the antibodies that combat them, which gets us closer to creating a malaria vaccine against the worst forms. The findings have been reported in Cell Host & Microbe.

This photomicrograph of a blood smear, revealed a type of white blood cell that had ingested a malaria parasite. / Credit: CDC/ Dr. Mae Melvin

Malaria parasites have a complex life cycle, and when they reach a human host, they head for the liver. They multiply there and are then released into the bloodstream, where they infect red blood cells and destroy them. Associate Professor Alyssa Barry, leader of the Systems Epidemiology of Infection at Deakin University, explained that once the parasites get into red blood cells, they add proteins called PfEMP1 to the surface of these cells.

"As part of their survival strategy within the human host, malaria parasites use PfEMP1 to stick to the walls of blood vessels, and this can cause blockages to blood flow and inflammation, leading to severe disease," Barry said. "Malaria parasites change these proteins to escape from developing immune responses, and every strain has a different set of proteins, making the identification of vaccine targets like finding a needle in a haystack."

By studying hundreds of variants of PfEMP1 proteins, a team of researchers has identified the antibodies that are best at battling severe forms of malaria. The scientists gathered hundreds of PfEMP1 proteins isolated from children in Papua New Guinea (PNG) that had been naturally infected with various strains of malaria.

"It's the first time anyone has shown this. For years, researchers have thought that developing a malaria vaccine based on PfEMP1 would be virtually impossible because the proteins are just so diverse," noted Barry.

"It's similar to the flu vaccine, where you have to keep adjusting and updating it as the virus strains evolve from year to year. Malaria is even more diverse than influenza; one village in a country such as PNG could contain thousands of possible PfEMP1 variants," Barry continued. "But in malaria-endemic areas, children who are repeatedly infected develop immunity to severe malaria by the time they're about two years old, so we know antimalarial immunity is possible, and it can develop after exposure to only a few strains."

Immunity to mild forms of the diseases was an obstacle to the work, but when malaria becomes severe, the immune system only targets a small group of proteins that are similar in different strains. This makes it easier to create a vaccine that would target these shared proteins.

Learn more about the lifecycle of the malaria parasite from the video.

"Using genomic sequencing, we collected PfEMP1 proteins from different strains of malaria, measured antibodies to those proteins to identify the protective antibody - the biomarker of immunity - that protects kids against disease," Barry added. "We were able to identify these antibodies by monitoring for patterns of disease, following the children in PNG for 16 months to determine which of them were susceptible to the more severe forms of the disease, and those who were protected and only experienced milder forms of the disease.

"Our study shows the potential of new approaches that combine measurement of large numbers of antibodies and carefully designed epidemiological studies," said Dr. Sofonias K. Tessema, who began the work as Barry's student and is now a postdoctoral fellow at University of California San Francisco.


Sources: AAAS/Eurekalert! via Deakin University, Cell Host & Microbe

About the Author
  • Experienced research scientist and technical expert with authorships on over 30 peer-reviewed publications, traveler to over 70 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
AUG 28, 2020
Cancer
Using CRISPR-Cas12a to Repair Hereditary Cancers in the Lab
AUG 28, 2020
Using CRISPR-Cas12a to Repair Hereditary Cancers in the Lab
Genome repair is one of the big-ticket research areas for the future of medicine. CRISPR-Cas9 systems can edit the genom ...
SEP 09, 2020
Microbiology
Changing How We Think of Drug Resistance in Fungi
SEP 09, 2020
Changing How We Think of Drug Resistance in Fungi
It's been estimated that fungal infections cause more than one million deaths worldwide, and many more are affected.
SEP 09, 2020
Cell & Molecular Biology
Why Liver Gene Therapies Have Not Worked & How to Improve Them
SEP 09, 2020
Why Liver Gene Therapies Have Not Worked & How to Improve Them
Diseases that are caused by errors in a gene might be cured if we could correct those errors, or genetic mutations.
SEP 20, 2020
Genetics & Genomics
Errors in the Nuclear Envelope Linked to Microcephaly
SEP 20, 2020
Errors in the Nuclear Envelope Linked to Microcephaly
Researchers have found that errors in a gene called LMNB1, which produces the lamin B1 protein, have devastating effects ...
NOV 07, 2020
Genetics & Genomics
How the Suction Cups on Octopus Arms Detect Their Surroundings
NOV 07, 2020
How the Suction Cups on Octopus Arms Detect Their Surroundings
Scientists have taken a close look at the physiology of the octopus, creatures that are ancient and unique. Their arms c ...
NOV 24, 2020
Genetics & Genomics
Cracking the Code of a Locust Swarm
NOV 24, 2020
Cracking the Code of a Locust Swarm
With a reputation for destruction that goes back to ancient Egypt, locust swarms are once again a major problem for some ...
Loading Comments...