It belongs to a group of viruses that includes the smallpox virus (variola), the virus used in the smallpox vaccine (vaccinia), and the cowpox virus.
a poxvirus closely related to smallpox virus; causes benign gelatinous tumors in humans.
Thanks to its resemblance to the smallpox virus, researchers were able to use vaccinia as a vaccine for the disease, eventually leading to its eradication in the late 1970s.
The U.S. smallpox viruses, which include samples from Britain, Japan and the Netherlands, are stored in liquid nitrogen.
