More than 20 years ago, Eckard Wimmer, a geneticist at Stony Brook University in New York, highlighted the potential dangers of synthetic biology in dramatic style when he recreated poliovirus in a test tube. Earlier this year, a team at the University of Alberta built an infectious horsepox virus. The virus is a close relative of smallpox, which may have claimed half a billion lives in the 20th century. Today, the genetic code of almost any mammalian virus can be found online and synthesised. The technology to do this is available now. It requires some expertise, but it’s something that’s relatively easy to do...