Tobacco plants engineered to manufacture high yields of malaria drug

In 2015, the Nobel Prize in Physiology or Medicine was awarded in part for the discovery of artemisinin, a plant-derived compound that's proven to be a lifesaver in treating malaria. Yet many people who need the drug are not able to access it, in part because it's difficult to grow the plant that is the compound's source. Now, research has shown that tobacco plants can be engineered to manufacture the drug at therapeutic levels. 

"Artemisinin treats malaria faster than any other drug. It can clear the pathogen from the bloodstream within 48 hours," says senior author Shashi Kumar, of the International Centre for Genetic Engineering and Biotechnology in New Delhi, India. "Our research is focused on finding a way to make this drug available to more people."

Earlier studies looked at growing the compound in tobacco – a plant that's relatively easy to genetically manipulate and that grows well in areas where malaria is endemic. But yields of artemisinin from those plants were low.

In the current paper, Kumar's team reports using a dual-transformation approach to boost the production of artemisinin in the tobacco plants: they first generated plants that contained transgenic chloroplasts, and the same plants were then manipulated again to insert genes into the nuclear genome as well.

Extract from the plants was shown to stop the growth progression of pathogen-infected red blood cells in vitro. Whole cells from the plant were also fed to mice infected with Plasmodium berghei, one of the microbes that causes malaria. The plant product greatly reduced the level of the parasite in the blood.

In fact, the researchers found, the whole plant material was more effective in attacking the parasite than pure artemisinin, likely because encapsulation inside the plant cells protected the compound from degradation by digestive enzymes.