An international team has found a genetic marker for the malaria-causing parasites that are resistant to artemisinin, an important drug for treating the mosquito-borne disease.
Among the researchers, who report their findings in a recent online issue of Nature, is a team from the National Institute of Allergy and Infectious Diseases (NIAID), part of the US National Institutes of Health.
The World Health Organization (WHO) estimates that 627,000 people died of malaria in 2012.
Artemisinin, combined with other drugs, is an important first line of defense against malaria. However, in recent years, development of artemisinin resistance in the malaria parasite Plasmodium falciparum in southeast Asia poses a real threat to global malaria control and elimination.
Thus, researchers are racing to find ways to keep the drug’s effectiveness. One important factor in the race is keeping track of the spread of artemisinin resistance.
For their study, the team sequenced the genetic information of a lab-generated strain of artemisinin-resistant P. falciparum, and also of two natural strains found in the wild in Cambodia – one drug-resistant and the other not. By comparing the genetic information from these three strains, they hoped to pinpoint the genetic marker of drug resistance.
And so they did. They found that P. falciparum carrying a mutant version of the K13-propeller gene was more likely to survive exposure to artemisinin in the lab.
Plus they found, in malaria patients treated with artemisinin, parasites carrying this particular genetic mutation took longer to eliminate.
And when they analyzed the geographical distribution of the K13-propeller mutated gene in parasites in western Cambodia, they found it matched the distribution of resistance among malaria patients in the same regions.
Taking these results together, the team concludes that the mutant K13-propeller gene is closely tied to artemisinin resistance and is likely to be a good molecular marker for it.
They say further research is now needed to find out how this mutation causes resistance and the extent to which it affects other geographical areas.
In another study reported earlier this year in the The Lancet Infectious Diseases, another group of scientists describe how they developed a rapid, simple way of testing for artemisinin resistance in a lethal form of malaria.