Scientists discover genetic marker of drug-resistant malaria

Date: Dec-19-2013An 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.

Mutant K13-propeller gene

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.

Written by Catharine Paddock PhD

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