West Nile virus
West Nile virus is a single-stranded RNA virus that causes West Nile fever. The virus is primarily transmitted by mosquitoes, mostly species of Culex. The primary hosts of WNV are birds, so that the virus remains within a bird–mosquito–bird transmission cycle.
About West Nile virus in brief
West Nile virus is a single-stranded RNA virus that causes West Nile fever. It is a member of the family Flaviviridae, specifically from the genus Flavivirus. The virus is primarily transmitted by mosquitoes, mostly species of Culex. The primary hosts of WNV are birds, so that the virus remains within a \”bird–mosquito–bird transmission cycle. Like most other flaviviruses, WNV is an enveloped virus with icosahedral symmetry. It has a 45–50 nm virion covered with a relatively smooth protein shell. The protein shell is made of two structural proteins: the glycoprotein E and the small membrane protein M. Protein E has numerous functions including receptor binding, viral attachment, and entry into the cell through membrane fusion. The genome is approximately 11,000 nucleotides long and is flanked by 5′ and 3′ non-coding stem loop structures. The coding region of the genome codes for three structural proteins and seven nonstructural proteins, proteins that are not incorporated into the structure of new viruses. The WNV genome is first translated into a polyprotein and later cleaved by virus and host proteases into separate proteins. The capsid proteins are one of the first proteins created in an infected cell; the capsid protein is a structural protein whose main purpose is to package RNA into the developing viruses. Once the positive-sense RNA has been synthesized, the WNV virion encloses the immature virions into the mature virions.
The mature viruses are then secreted out of the cell by secretions of the Japanese encephalitis virus, a type of West Nile virus. WNV virus is then transferred to non-infectious non-Japanese mosquitoes, which carry the disease to humans and other mammals. It can also be transmitted to humans by infected mosquitoes, such as the yellow fever virus, the dengue virus, and the zebrafish virus. The viral envelope is covered by a host-derived lipid membrane, the viral envelope. The membrane has been found to contain cholesterol and phosphatidylserine, but other elements of the membrane have yet to be identified. Once WNV has successfully entered the bloodstream of a host animal, the envelope protein, E, binds to attachment factors called glycosaminoglycans on the host cell. The acidity of the endosomal and viral membranes, allowing the genome to be released into the cytoplasm. The RNA genome is bound to capsid proteins, which are 105 amino-acid residues long, to form the nucleocapsid. The protein is then cleaved into mature proteins by both host and viral proteases to produce mature proteins. In order to replicate its genome, a polymerase, NS5, a negative-sense strand synthesis complex, serves as a template for the final positive- sense RNA strand.