Structural proteins (C, prM/M, E) are capsid, precursor membrane proteins, and envelope proteins, respectively. The WNV genome is first translated into a polyprotein and later cleaved by virus and host proteases into separate proteins (i.e. The coding region of the genome codes for three structural proteins and seven nonstructural (NS) proteins, proteins that are not incorporated into the structure of new viruses. Its genome is approximately 11,000 nucleotides long and is flanked by 5′ and 3′ non-coding stem loop structures. WNV is a positive-sense, single-stranded RNA virus. The capsid has been found to prevent apoptosis by affecting the Akt pathway. 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. The RNA genome is bound to capsid (C) proteins, which are 105 amino-acid residues long, to form the nucleocapsid. The two viral envelope proteins, E and M, are inserted into the membrane. Cholesterol, in particular, plays an integral part in WNV entering a host cell. The lipid membrane has many roles in viral infection, including acting as signaling molecules and enhancing entry into the cell. The flavivirus lipid membrane has been found to contain cholesterol and phosphatidylserine, but other elements of the membrane have yet to be identified. The outer protein shell is covered by a host-derived lipid membrane, the viral envelope. Protein E has numerous functions including receptor binding, viral attachment, and entry into the cell through membrane fusion. The protein shell is made of two structural proteins: the glycoprotein E and the small membrane protein M. Electron microscope studies reveal a 45–50 nm virion covered with a relatively smooth protein shell this structure is similar to the dengue fever virus, another Flavivirus. Like most other flaviviruses, WNV is an enveloped virus with icosahedral symmetry. Most likely, it spread from the original West Nile district. After its original discovery in this region, it was found in many other parts of the world. ![]() Humans and horses both exhibit disease symptoms from the virus, and symptoms rarely occur in other animals.Ĭontrary to popular belief, West Nile virus was not named after the Nile River, rather, the West Nile district of Uganda where the virus was first isolated in 1937. The virus is genetically related to the Japanese encephalitis family of viruses. The primary hosts of WNV are birds, so that the virus remains within a "bird–mosquito–bird" transmission cycle. The virus is primarily transmitted by mosquitoes, mostly species of Culex. It is a member of the family Flaviviridae, from the genus Flavivirus, which also contains the Zika virus, dengue virus, and yellow fever virus. West Nile virus ( WNV) is a single-stranded RNA virus that causes West Nile fever. ![]() Ribbon representation of the NS2B/NS3 protease of West Nile virus
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