A more realistic risk is that terrorists could order genes thatfconfer virulence to dangerous pathogens such as the Ebola virus, and engineer them into another virus or bacterium. They could also order genes for a hazardous bacterial toxin although many of these are also available by isolating the microorganisms from the environment.
Virulence genes are typically no more than a few thousand base-pairs long. Their sequences are publicly available, so screening gene-synthesis orders for potential bioweapons shouldn't pose a huge challenge. Indeed, a company called Craic Computing,based in Seattle, has written opensource software called Blackwatch that does just that. It is used by one of the leading gene-synthesis companies, Blue Heron Biotechnology of Bothell, Washington.
Robert Jones, president of Craic Computing, says that Blackwatch "casts a wide net", comparing orders against sequences from organisms identified by the US government as "select agents" that raise bioterror concerns. But not all of these sequences are dangerous, and some customers may have the clearance to work with those that are. So even legitimate orders may be flagged up as suspicious, and that means companies must employ biologists to carefully examine any matches that crop up.
The need for expert human checks may be one factor deterring some companies from screening orders. Others like to reassure customers who may be worried about commercial confidentiality that their sequence data will remain secret. But whatever the reasons, some firms freely admit tha