Flaviviridae, commonly flavivirus, flaviviral, and flaviviruses, is a family of enveloped positive-strand RNA viruses which mainly infect mammals and birds. They are primarily spread through arthropod vectors (mainly ticks and mosquitoes). The family gets its name from the yellow fever virus; flavus is Latin for "yellow", and yellow fever in turn was named because of its propensity to cause jaundice in victims. The family has five genera. Diseases associated with the group include: hemorrhagic fever, encephalitis, and the birth defect microcephaly.
Structure
Virus particles are enveloped and spherical with icosahedral-like geometries that have pseudo T=3 symmetry. They are about 40–60 nm in diameter.
Host range and evolutionary history
A wide variety of natural hosts are used by different members of the Flaviviridae, including fish, mammals including humans and various invertebrates, such as those specific to mollusks and crustaceans. The genomes of these flaviviruses show close synteny with that of the yellow fever virus. One flavivirus, the Wenzhou shark flavivirus, infects both Pacific spadenose sharks (Scoliodon macrorhynchos) and Gazami crabs (Portunus trituberculatus) with overlapping ranges, raising the possibility of a two-host marine lifecycle.
Flavivirus endogenous viral elements, traces of flavivirus genomes integrated into the host's DNA, are found in many species, including a tadpole shrimp Lepidurus articus, the water flea Daphnia magna and a freshwater jellyfish Craspedacusta sowerbii, As more viruses particularly classified under separate genera became established, the names became confusing. The ICTV therefore resolved in 2023 that the genus Flavivirus should be replaced with Orthoflavivirus and that the common names can be used for the entire family.
The family has the following genera:
- Guaicovirus
- Jingmenvirus
- Orthoflavivirus
- Tamanavirus
- Termitovirus
Clinical importance
Major diseases caused by members of the family Flaviviridae include: