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| {{West nile virus}}
| | #REDIRECT [[West nile virus]] |
| {{CMG}}
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| ==Overview==
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| ==Taxonomy==
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| Viruses; ssRNA viruses; ssRNA positive-strand viruses, no DNA stage; Flaviviridae; Flavivirus; Japanese encephalitis virus group<ref name=NCBI>{{cite web | title = West Nile Virus | url = http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=11082&lvl=3&lin=f&keep=1&srchmode=1&unlock }}</ref>
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| ==Biology==
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| {| style="float: right;"
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| | [[File:WNV.jpg|200px|thumb|none| Digitally-colorized transmission electron micrograph (TEM) of the West Nile virus (WNV).<SMALL> ''Image provided by the CDC [http://phil.cdc.gov/phil/details.asp Centers for Disease Control and Prevention] ''<ref>{{Cite web | title = http://phil.cdc.gov/phil/details.asp | url = http://phil.cdc.gov/phil/details.asp}}</ref></SMALL>]]
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| | [[File:WNV2.jpg|200px|thumb|none| Presence of West Nile virus virions, in an isolate that was grown in a cell culture.<SMALL> ''Image provided by the CDC [http://phil.cdc.gov/phil/details.asp Centers for Disease Control and Prevention] ''<ref>{{Cite web | title = http://phil.cdc.gov/phil/details.asp | url = http://phil.cdc.gov/phil/details.asp}}</ref></SMALL>]]
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| West Nile virus is a member of Japanese encephalitis serocomplex and belongs to the [[genus]] [[Flavivirus]], family [[Flaviviridae]]. The virus has an icosahedral symmetry, with a smooth surface.<ref name="Mukhopadhyay2003">{{cite journal|last1=Mukhopadhyay|first1=S.|title=Structure of West Nile Virus|journal=Science|volume=302|issue=5643|year=2003|pages=248–248|issn=0036-8075|doi=10.1126/science.1089316}}</ref> It is an enveloped virus with a nucleocapsid core built of [[RNA]] and [[capsid]] proteins. Its [[genome]] is contained in a single stranded [[mRNA]] virus of about 11000 bp.<ref name="CampbellMarfin2002">{{cite journal|last1=Campbell|first1=Grant L|last2=Marfin|first2=Anthony A|last3=Lanciotti|first3=Robert S|last4=Gubler|first4=Duane J|title=West Nile virus|journal=The Lancet Infectious Diseases|volume=2|issue=9|year=2002|pages=519–529|issn=14733099|doi=10.1016/S1473-3099(02)00368-7}}</ref> It contains a single [[ORF]], a 5' [[UTR]], and a 3' region which is not translated. The ORF contains a single polyprotein, that after processed and translated produces 3 smaller types of structure proteins and 7 of non-strutural proteins.
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| * Structure proteins are responsible for the formation of the viral particle and include:
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| :* Envelope proteins
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| :* Membrane proteins
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| :* C proteins
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| * Non-structure proteins are responsible for viral replication, evasion of the immune system and assembly of virions, and include:
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| :*NS1
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| :*NS2A
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| :*NS2B
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| :*NS3
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| :*NS4A
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| :*NS4B
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| :*NS5
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| The West Nile Virus may be classified in 5 phylogenetic lineages. Of these, only 1 and 2 have been identified as causative agents of disease in humans.<ref name=CDC>{{cite web | title = West Nile Virus | url = http://wwwnc.cdc.gov/eid/article/10/1/pdfs/02-0616.pdf }}</ref>
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| Lineage 1 can be further subdivided into 3 sublineages: iso- lates from the western hemisphere, Africa, the Middle East, and Europe constitute lineage 1a; Kunjin virus from Australasia repre- sents lineage 1b; and lineage 1c consists of viruses from India.16 The initial North American isolates (East Coast genotype) identi- fied in 1999 in New York City have been most closely related to a lineage 1a West Nile virus isolated from Israel in 1998.17 Since approximately 2002, the East Coast genotype has largely been displaced by a new genotype (WN02 genotype) encompassing several conserved amino acid substitutions that may have increased the efficiency and rapidity of viral transmission in North American mosquito vectors.7,18
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| ==Structure==
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| ==Tropism==
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| ==Natural Reservoir==
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| Natural reservoirs of the West Nile virus include:<ref name="pmid23860989">{{cite journal| author=Petersen LR, Brault AC, Nasci RS| title=West Nile virus: review of the literature. | journal=JAMA | year= 2013 | volume= 310 | issue= 3 | pages= 308-15 | pmid=23860989 | doi=10.1001/jama.2013.8042 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23860989 }} </ref>
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| * Humans
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| * 65 different species of mosquitos
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| * 326 [[species]] of birds
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| *West Nile virus was first identified in 1937 in Uganda in eastern Africa. It was first discovered in the United States in the summer of 1999 in New York. Since then, the virus has spread throughout the United States.
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| *The West Nile virus is a type of virus known as a [[flavivirus]]. Researchers believe West Nile virus is spread when a mosquito bites an infected bird and then bites a person.
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| *Mosquitos carry the highest amounts of virus in the early fall, which is why the rate of the disease increases in late August to early September. The risk of disease decreases as the weather becomes colder and mosquitos die off.
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| *Although many people are bitten by mosquitos that carry West Nile virus, most do not know they've been exposed. Few people develop severe disease or even notice any symptoms at all.
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| *West Nile virus may also be spread through [[blood transfusions]] and [[organ transplants]]. It is possible for an infected mother to spread the [[virus]] to her child through [[breast milk]].
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| ==References==
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| {{Reflist|2}}
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