Jacquin Niles of the Massachusetts Institute of Technology in the U.S. is developing a method to switch individual genes on and off in the malaria-causing parasite Plasmodium falciparum for evaluating candidate and existing antimalarial drugs. In Phase I, they built and tested a scalable TetR-aptamer system for rapidly and easily manipulating gene expression in the parasite genome, and showed that it could be used to validate the target of a 4-aminoquinoline antimalarial drug.