Malaria’s new guises

The complicated life cycle of the malaria parasite has just taken another swerve. Scientists have observed Plasmodium falciparum enjoying three distinct lifestyles in the blood of infected children. Two of these three states have never been seen before, and one of those two appears to cause an unusually severe illness.

RING CYCLE. The malaria parasite (yellow-white ovals) infects red blood cells (big red discs) during the “ring” stage of its complicated life cycle. Researchers have found the parasite lives in one of three distinct ways during the ring stage. iStockphoto

The findings highlight new targets for future anti-malaria drugs, says the Massachusetts Institute of Technology’s Aviv Regev, a computational biologist involved in the study.

For the research, scientists developed a new technique to isolate messenger RNA from the parasite as it infects red blood cells. This messenger RNA paints a profile showing which of the parasite’s 6,000 genes are switched on, and to what degree. The researchers found three distinct genetic profiles in parasites from 43 infected children in Senegal.

One genetic profile resembled an active-growth state also seen during lab studies of P. falciparum. But the other two profiles were new. In one, the parasite appears to be starving. In the other, it’s stressed out.

The 17 patients whose parasites were in the stressed state suffered worse symptoms than the others. “They had a higher fever, they had the disease for longer, and they had a higher load of parasites in their blood,” says Regev. The study appears online in Nature.

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