The study, published early this month (2 January) in Nature, was based on a five-year research project that created malaria mutations in a lab based on a sample retrieved from a malaria patient in Tanzania.
The researchers found mutations inside the so-called ‘propeller’ domain of the Kelch, or K13 protein, potentially offering clues into how resistance to artemisinin has developed in Cambodia, where the first case of resistant malaria strains were discovered in the early 2000s.
Drug-resistant strains were later discovered in Myanmar, Thailand and Vietnam, and researchers and health officials now worry that the strains could spread to Bangladesh, India and countries in Africa.
“It clearly demonstrates that a mutation in a specific Kelch-propellor protein results in resistance to artemisinin,” Ian Graham, head of the biology department at the University of York in Britain, says of the study.
Graham led a team of scientists that published in 2010 a genetic map of Artemisia annua plant, the source of artemisinin which is the most potent drug against the malaria parasite. Artemisinin is made from the sweet wormwood plant and used in traditional Chinese medicines.
The WHO recommends a combination of artemisinin and other drugs as the first-line treatment for basic malaria infections. It says that artemisinin typically reduces a patient’s “parasite load” while a partner drug eliminates remaining parasites, typically curing patients in two days.
According to the study in Nature, the studies in Cambodia in the early 2000s documented cases in which patients were cured after five days, or not at all, by artemisinin treatments. The WHO says resistance is linked to poor treatment, substandard versions of artemisinin, and reluctance by some patients to complete their treatment regimens.
The study’s lead researcher, Frederic Ariey, a malaria expert at the Pasteur Institute in Paris was not available to comment for this article.
Graham explains that the identification of a molecular marker will allow scientists to track the spread of resistance to artemisinin, and for future research to help understand how the resistance developed and possibly come up with ways to overcome such resistance.
“We do not understand the precise mode of action of artemisinin and such research is important,” he adds. “The Kelch propellor protein could be interacting directly or indirectly with the drug.”
Link to abstract of paper
This article has been produced by SciDev.Net South-East Asia & Pacific desk.