Base composition

17th Century Variola Virus Reveals the Recent History of Smallpox …our data clearly show that the VARV lineages eradicated during the 20th century had only been in existence for ∼200 years… Reported as: Smallpox, once thought an ancient disease, may have emerged in more recent times … smallpox virus evolved into two circulating strains, variola … Energy-dependent natural translational selection