If resurrecting horsepox virus provides a roadmap to synthesizing smallpox virus, then why would anyone try to synthesize it? Because there are potentially legitimate uses for it. Tonix claims that the horsepox virus is a good candidate for developing a new, safer smallpox vaccine. Horsepox virus, smallpox virus, and the vaccinia virus that is used in smallpox vaccines are part of a closely related group of pox viruses. Vaccinia is the most well-understood of the pox viruses and is popular with scientists because it can stably integrate large segments of foreign DNA. Engineering pox viruses, such as vaccinia, could help create new vaccines and cancer therapies. But any lab that creates these beneficial applications through synthetic biology would also have the capability to produce infectious smallpox virus from synthetic DNA.

Unfortunately, the current legal and technical safeguards against the synthesis of smallpox virus are weak and fragmented. There is no clear international legal or regulatory framework to prevent the synthesis of smallpox virus. The WHO has a policy banning the synthesis of the smallpox and regulating who can produce and possess large fragments of smallpox DNA, but it hasn’t been widely adopted by states. Furthermore, there is no mechanism—at either the national or international level—for detecting or punishing violations of this policy.