Flaviviridae (virus )

by - November 20, 2018



Flaviviridae is a family of viruses. Humans and other mammals serve as natural hosts. They are primarily spread through arthropod vectors (mainly ticks and mosquitoes). The family gets its name from the Yellow Fever virus, the type virus of Flaviviridae; flavus means yellow in Latin, and Yellow fever in turn was named because of its propensity to cause jaundice in victims. There are currently over 100 species in this family, divided among four genera. Diseases associated with this family include: hepaciviruses, hepatitis, pestiviruses, hemorrhagic syndromes, abortion, fatal mucosal disease, flavivirus, hemorrhagic fever, encephalitis, and the birth defect microcephaly.

Taxonomy

Genus Flavivirus (type species Yellow fever virus, others include West Nile virus, Dengue Fever and Zika virus)—contains 67 identified human and animal viruses
Genus Hepacivirus (type species Hepatitis C virus, also includes GB virus B)
Genus Pegivirus (includes GB virus A, GB virus C, and GB virus D)
Genus Pestivirus (type species bovine viral diarrhea virus, others include classical swine fever or hog cholera)—contains viruses infecting non-human mammals
Group: ssRNA(+)

Order: Unassigned

Genome

Flaviviridae have monopartite, linear, single-stranded RNA genomes of positive polarity, 9.6 to 12.3 kilobase in length. The 5'-termini of flaviviruses carry a methylated nucleotide cap, while other members of this family are uncapped and encode an internal ribosome entry site.

Virion structure

Virus particles are enveloped, with icosahedral and spherical geometries, about 40–60 nm in diameter.

Genus Structure Symmetry Capsid Genomic Arrangement Genomic Segmentation
Hepacivirus Icosahedral-like Pseudo T=3 Enveloped Linear Monopartite
Flavivirus Icosahedral-like Pseudo T=3 Enveloped Linear Monopartite
Pegivirus Icosahedral-like Pseudo T=3 Enveloped Linear Monopartite
Pestivirus Icosahedral-like Pseudo T=3 Enveloped Linear Monopartite
Life Cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by attachment of the viral envelope protein E to host receptors, which mediates clathrin-mediated endocytosis. Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription is the method of transcription. Translation takes place by viral initiation. The virus exits the host cell by budding. Humans and mammals serve as the natural host. The virus is transmitted via a vector (ticks and mosquitoes).

Genus Host Details Tissue Tropism Entry Details Release Details Replication Site Assembly Site Transmission
Hepacivirus Humans Epithelium: skin; epithelium: kidney; epithelium: intestine; epithelium: testes Clathrin-mediated endocytosis Secretion Cytoplasm Cytoplasm Sex; blood
Flavivirus Humans; mammals; mosquitoes; ticks Epithelium: skin; epithelium: kidney; epithelium: intestine; epithelium: testes Clathrin-mediated endocytosis Secretion Cytoplasm Cytoplasm Zoonosis; arthropod bite
Pegivirus Mammals None Clathrin-mediated endocytosis Secretion Cytoplasm Cytoplasm Unknown
Pestivirus Mammals None Clathrin-mediated endocytosis Secretion Cytoplasm Cytoplasm Vertical: parental
Clinical importance

Major diseases caused by the Flaviviridae family include:

Dengue fever
Hepatitis C Virus Infection
Japanese encephalitis
Kyasanur Forest disease
Murray Valley encephalitis
St. Louis encephalitis
Tick-borne encephalitis
West Nile encephalitis
Yellow fever
Zika fever

source - Wikipedia
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