Burnet and PNG-IMR researchers have studied 200 children in PNG to see how their immune system responds to malaria. Photo courtesy of Brett Balalas.
By Julia Medew, Health Editor, The Age
Australian researchers have found promising new targets for a vaccine to prevent malaria, a disease that kills more than 600,000 people every year.
Researchers at Melbourne’s Burnet Institute and the Papua New Guinea Institute of Medical Research recently studied 200 children in PNG to see how their immune systems had responded to malaria parasites commonly found in the region.
They found many of the children had developed natural immunity to the disease through antibodies that target specific malaria proteins.
Dr Jack Richards, an infectious disease physician who worked on the study, said identifying these proteins was exciting because it meant scientists could try to mimic the children’s natural response in a vaccine.
He said the children’s antibodies appeared to block the malaria proteins from engaging with red blood cells - the process during which malaria infects red blood cells and makes people sick. Dr Richards said the new proteins appeared to be better targets than other proteins unsuccessfully used in vaccine development.
‘'This is a big step forward scientifically. It gives us cause for optimism,’‘ he said.
‘'It may be that we’ve been looking at the wrong proteins for many years. There are a whole lot of new candidates that really deserve a strong focus now.’'
Malarial parasites are carried by mosquitoes in tropical regions in Asia, Africa, and Central or South America.
When an infected mosquito bites a human, the parasites migrate to the liver and then start multiplying.
After one to two weeks, the parasites return to the bloodstream to invade and multiply inside red blood cells. They then burst out, releasing new parasites, which then invade fresh red blood cells and continue the cycle of proliferation.
Dr Richards said the team was hoping to find a vaccine that would exploit the small window of opportunity when the parasite bursts out of red blood cells into others because this was the point when the disease started producing symptoms such as fever and chills.
‘'We want to stop people getting sick and dying from malaria, so if we can generate immunity at the blood stage, that’s where we’ll have the biggest impact,’‘ he said.
The World Health Organization says about 220 million people are diagnosed with malaria each year and of those about 660,000 die. Pregnant women and children are especially vulnerable to the disease, which is endemic in many of Australia’s neighbouring countries. About 350 Australians are infected each year while travelling abroad.
While treatments are available, Dr Richards said there was growing concern resistance was developing to the most effective drugs and insecticides used in bed nets and insect sprays to control the mosquitoes that transmit malaria.
‘'We’re really hopeful that over the next five or so years we can make some real progress [towards a vaccine],’‘ he said.
This research was conducted in collaboration with the PNG-IMR and the Walter and Eliza Hall Institute, Japan’s Ehime University and Case Western Reserve University, USA.
CLICK HERE for the Journal of Immunology paper on this research.