Every day in Africa alone, 2000 children die from malaria, as biting mosquitoes spread the infection between humans. And despite years of working toward a vaccine, scientists have been unable to unleash a suitably potent weapon against the disease.
But now, Dutch researchers have characterized a large number of parasite proteins that could prove useful in the development of a human malaria vaccine. Details were published in the Oct. 31 issue of the open-access journal PLoS Pathogens.
According to the study, after being injected by a mosquito, parasites migrate to the liver, where they mature and release their sporozoites (or infective cells) into the bloodstream, resulting in disease and fatal complications. One promising method for vaccination is to attack these parasites, weakening them so that their invasion of the liver stimulates an immune response, stalling their development. The researchers were able to genetically inactivate individual parasite genes that are active during the growth phase in the liver.
Studies had previously shown how to successfully vaccinate mice using a rodent malaria which had one of these liver stage genes removed; a group of collaborating researchers also completed the first transition of such a vaccination from the rodent system to humans by inactivating the equivalent gene in the major human malaria parasite.
This study marks the first time that genetic modification of a human parasite resulted in its growth arrest in a liver cell, opening up promising possibilities for its use as a human vaccine.
“This study sheds light not only on the development and maturation of the malaria parasite in an Anopheles mosquito but also identifies proteins that are uniquely synthesized as the sporozoite becomes increasingly infectious to humans,” the authors wrote. “Understanding the sporozoite and all its various developmental steps during the establishment of an infection continues to represent a promising approach in the hunt for new weapons in the fight against malaria.”