Flaviviridae

The family Flaviviridae comprises the genus Flavivirus. which contains 65 related species and two possible members. They are small, enveloped RNA viruses (diameter 45 nm) with peplomers comprising a single glycoprotein E. Other structural proteins are designated C (core) and M (membrane-like). The single strand of RNA is infectious and has a molecular weight of about 4 × 10⁶ and an m⁷G ‘cap’ at the 5′ end but no poly(A) tract at the 3′ end: It functions as the sole messenger. The gene sequence commences 5′-C-M-E… The replication strategy and the mode of morphogenesis are distinct from those of the Togaviridae which are slightly larger and morphologically similar in some respects. Flaviviruses infect a wide range of vertebrates, and many are transmitted by arthropods.