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Flavivirus is a genus of the family Flaviviridae. This complex includes the West Nile virus, dengue virus, Tick-borne Encephalitis Virus, Yellow Fever Virus, and several other viruses which cause encephalitis.
Additional recommended knowledge
Flavivirus share a common size (40-65 nm), symmetry (enveloped, icosahedral nucleocapsid), nucleic acid (positive-sense, single stranded RNA approximately 10,000-11,000 bases), and appearance in the electron microscope. Rats carry flavivirues, but whether they can transmit them is in question.
Flavivirus have a (+) sense RNA genome and replicate in the cytoplasm of the host cells. The genome mimics the cellular mRNA molecule in all aspects except for the absence of the poly-adenylated (poly-A) tail. This feature allows the virus to exploit cellular apparatus to synthesise both structural and non-structural proteins, during replication. The cellular ribosome is crucial to the replication of the flavivirus, as it translates the RNA, in a similar fashion to cellular mRNA, resulting in the synthesis of a single polyprotein.
Once translated, the polyprotein is cleaved by a combination of viral and host proteases to release mature polypeptide products. Nevertheless, cellular post-translational modification is dependent on the presence of a poly-A tail; therefore this process is not host-dependent. Instead, the polyprotein contains an autocatalytic feature which automatically releases the first peptide, a virus specific enzyme. This enzyme is then able to cleave the remaining polyprotein into the individual products. One of the products cleaved is a polymerase, responsible for the synthesis of a (-) sense RNA molecule. Consequently this molecule acts as the template for the synthesis of the genomic progeny RNA.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Flavivirus". A list of authors is available in Wikipedia.|