1. Diseases associated with this subfamily include : Variola virus : smallpox. 2. For example, vaccinia virus is used to prevent smallpox, which is caused by variola virus. 3. Camelpox, taterapox and variola viruses arose 3, 500 years ago and horsepox virus ~ 3, 000. 4. Variola virus and Camelpox virus form a subgroup. 5. Smallpox, caused by variola virus, spreads easily and is fatal up to 30 percent of the time. 6. Smallpox is caused by the variola virus. 7. Variola virus infects only humans in nature, although primates and other animals have been infected in a laboratory setting. 8. The WHO committee that made the genetic engineering recommendation is the international organization's Advisory Committee on Variola Virus Research. 9. Currently, imatinib and related compounds are being evaluated by the CDC for their efficacy against variola virus and monkeypox virus. 10. In 1999, he was one of several scientists to argue for the destruction of the remaining stocks of variola virus.