Not all viruses set out to cause widespread death and sickness — some have the potential to fight cancer, according to new research.

Researchers from Hokkaido University in Japan have genetically engineered adenoviruses, which is a family of viruses that cause mild symptoms, to replicate inside cancer cells and kill them, according to a new paper in the journal Cancers.

To do this, Fumihiro Higashino, a molecular oncologist, and his team inserted adenylate-uridylate-rich elements (AREs) from two human genes — a stabilizing element found in a type of macromolecule present in all biological cells — into two strains of the virus to help specifically attack cancer cells.