Variola virus

Common card · No. 262156

Variola virus is the causative agent of smallpox, a formerly widespread and dangerous disease in humans. The virus is large and brick-shaped and is approximately 330 by 260 nm, with a single linear double-stranded DNA genome 186 kilobase pairs (kbp) in size and containing a hairpin loop at each end. It infects only humans in nature. Both enveloped and unenveloped virions are infectious. Infection with either the major or minor strain confers immunity against the other. Variola major, the more common of the two strains, caused the more clinically severe illness and accounted for the great majority of smallpox's historical mortality. The genome of variola major virus is about 186,000 base pairs in length. It is made from linear double-stranded DNA and contains the coding sequence for about 200 genes. The center of the genome contains the majority of the essential viral genes, including for structural proteins, DNA replication, transcription, and mRNA synthesis. The ends of the genome vary...

Read on Wikipedia · Image Content Providers(s): CDC/ Dr. Fred Murphy; Sylvia Whitfield, Public domain