It is very rare, but some people’s blood can block transmission of malaria parasites, preventing the spread of the disease. How do you track down those people and what is in these people’s blood? The team of epidemiologist Teun Bousema of Radboudumc developed a test for this: they mix the blood serum of people who may be immune with cultured malaria parasites and feed a cage of mosquitoes with it. Occasionally it appears that the serum prevents the parasites from spreading via the mosquitoes.
“We screened the blood serum of hundreds of people in this way, mainly from Africa. They were all exposed to malaria,” says Bousema. “In the end, two of them showed very strong and long-lasting immunity against the spread of parasites: a Dutch missionary, whose blood had been in the freezer for thirty years, and a little girl from Uganda.” Researcher Matthijs Jore then set to work with an international team to find out which substances in the blood are so special that they prevent the spread of the malaria parasite.
Vaccine against spread
The research team found more than a hundred antibodies in the blood of the missionary and the girl, which could play a role in their strong defense against malaria. Antibodies are substances produced by the body that are very specifically directed against a foreign substance, in this case against two different proteins on a malaria parasite, which are important for the spread via mosquitoes. “We tested all those antibodies separately in the lab; which antibody best prevents the spread of parasites, and which antibodies do nothing?” says Jore. “All those antibodies contain important information for a vaccine against malaria.”
In doing so, Jore’s team studied the antibodies in great detail, together with colleagues from The Hospital for Sick Children in Toronto. He not only examined which proteins they were targeting, but also which part of the proteins. Jore: “We saw that the most powerful antibodies were always directed against the same parts of the proteins. We are now using this information to develop a new vaccine against the spread of malaria.”
Protect young children
The need for new vaccines against malaria is still great. Despite many investments and efforts, 600,000 people die of malaria every year, mainly young children. “The spread of malaria via mosquitoes is very efficient: one person can infect up to a hundred other people. Preventing the spread of malaria is therefore an essential part of fighting malaria,” says Jore. “Our research is a big step towards an effective vaccine against the spread of this disease. That we were able to investigate the naturally built-up immunity of the Ugandan missionary and girl so extensively seems to be a key to success.”
By: National Care Guide