Zika belongs to the virus family Flaviviridae and the genus Flavivirus. Its name comes from the Zika Forest of Uganda, where the virus was first isolated in 1947. Zika virus is related to dengue, yellow fever, Japanese encephalitis, and West Nile viruses.
There are two lineages of the Zika virus: the African lineage, and the Asian lineage. Phylogenetic studies indicate that the virus spreading in the Americas is most closely related to the Asian strain, which circulated in French Polynesia during the 2013 outbreak.
Zika virus is enveloped by the viral coat. These structural proteins encapsulate the virus. The virus contains host-derived elementary membrane (lipid bilayer). Underneath the membrane lies the viral capsid - the proteins enclosing the viral genetic material.
Zika virus has a nonsegmented, single-stranded, positive-sense RNA genome. This positive-sense RNA genome can be directly translated into viral proteins. The replicated RNA strand is held within a nucleocapsid formed from 12-kDa protein blocks.