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Researchers have identified a promising target for a vaccine against malaria in pregnant women.
A team of researchers led by Ali Salanti, of the University of Copenhagen in Denmark, found that women who are normally immune to malaria are made vulnerable to it during pregnancy by a molecule that is made by the placenta.
This molecule binds to another, known as VAR2CSA, which the scientists have found is produced by the malaria parasite after it has infected red blood cells. As a result, the infected red blood cells become trapped in the placenta, favouring the development of the disease.
The researchers, who published their findings in the Journal of Experimental Medicine, believe that blocking VAR2CSA could be the key to reducing the disease in pregnant women.
Most people living in areas where malaria is endemic develop immunity by the time they are adults. Pregnant mothers are an exception to this rule. Because the parasites that infect the placenta do so in a way that is unlike conventional infection, they pass under the immune system’s ‘radar’.
This means that even women who are immune to malaria can develop the disease during pregnancy. In some women, however, the mechanism that traps infected blood cells in the placenta is naturally disrupted.
Earlier this year, Lars Hviid also of the University of Copenhagen in Denmark, and one of the collaborators on the Journal of Experimental Medicine paper, published a study of women whose immune systems are particularly capable of targeting the type of proteins that VAR2CSA belongs to.
Hviid and his colleagues showed that these women have a better chance of giving birth to heavier, healthier babies. Salanti’s study confirmed this finding.
The researchers believe that vaccinating women against VAR2CSA will give them immunity to infection during pregnancy.
In an accompanying commentary in the journal, Joseph Smith of the Seattle Biomedical Research Institute, and Kirk Deitsch of Weill Medical College of Cornell University, say the findings are an important step in understanding how malaria infects pregnant women.
Pregnancy-associated malaria is responsible for high levels of disease and illness. Estimates suggest that about 2,500 mothers and 300,000 foetuses and infants die from malaria each year.