Matthias Gromeier, M.D., assistant professor of molecular genetics and microbiology at the Duke Comprehensive Cancer Center, said “we made a drug out of a virus by engineering its destructive abilities from a foe into a friend”. The key to Gromeier’s success has been disabling the poliovirus’ ability to kill normal brain cells while retaining its ability to kill cancer cells in the brain. To do so, Gromeier’s team swapped a critical genetic element from the common cold “rhinovirus” with the corresponding genetic element from the poliovirus. The genetic element, called an “IRES” (internal ribosomal entry site), enables a virus to express its own genetic information inside the host cell it has invaded, said Gromeier.