U.S. researchers say a cheap way to produce an expensive but effective malaria drug is well on the way.
The researchers have created a modified form of the yeast Saccharomyces cerevisiae that is capable of producing large amounts of artemisinic acid, which is needed to make the anti-malaria drug artemisinin.
Artemisinin is currently expensive to manufacture, and is out of reach for many in the developing world.
Malaria infects as many as 500 million people a year, and kills more than 1.5 million, mainly in Africa and Asia.
It is caused by the one-celled parasite carried by mosquitoes called plasmodium, and kills mostly young children.
Artemisinin is the drug of choice for treating multi-drug resistant strains of plasmodium species as used in combination with other drugs it has proved to be nearly 100% effective.
It is presently extracted from a plant called Artemisia annua commonly known as sweet wormwood, and grown by farmers in Asia.
The drug is expensive and supplies are limited, meaning that many malaria patients in developing countries go untreated.
Dr. Jay D. Keasling, from the University of California at Berkeley, and colleagues succeeded two years ago in engineering bacteria to make a chemical precursor of artemisinin.
They say they have now developed a strain of yeast that can churn out large quantities of artemisinic acid, a chemical just a few steps away from the drug itself.
They apparently did this by adding two genes from Artemisia annua to the yeast, Saccharomyces cerevisiae.
This means in theory that it should now be possible to manufacture the drug much more cheaply.
Professor Keasling says however that it could still be several years before a microbe-produced version of artemisinin will be widely available.
The research is published in the current edition of Nature.