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| ==[[West nile virus historical perspective|Historical Perspective]]== | | ==[[West nile virus historical perspective|Historical Perspective]]== |
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| __NOTOC__
| | ==[[West nile virus causes|Causes]]== |
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| {{West nile virus}}
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| {{About0|West nile virus}}
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| {{CMG}}
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| ==Overview==
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| WNV is an enveloped positive-sense ssRNA virus of 11000 base pairs (bp) that is considered a member of the Japanese encephalitis serocomplex. It belongs to the genus Flavivirus and family Flaviviridae. Its RNA encodes structural and non-structural proteins. Although 7 lineages of WNV have been described, only lineage 1 and 2 are clinically significant. The viral natural reservoir includes many species, such as humans, horses, dogs, and cats; but the main natural reservoir is birds.
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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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| WNV is a member of Japanese encephalitis serocomplex and belongs to the [[genus]] [[Flavivirus]], family [[Flaviviridae]]. Other [[species]] of the this serocomplex include the [[St Louis encephalitis virus]] and the [[Japanese encephalitis virus]].<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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| The WNV 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 [[RNA]] 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 open reading frame ([[ORF]]), a 5' untranslated region ([[UTR]]), and another 3' region which is also not translated. The ORF contains a single polyprotein that produces 3 smaller types of structure proteins and 7 of non-structural proteins following processing and translation.
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| * Structural 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-structural proteins are responsible for viral replication, evasion of the immune system, and assembly of virions. They 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 WNV may be classified in 7 phylogenetic lineages. Of these, only 1 and 2 have been identified as causative agents of disease in humans and are considered clinically significant.<ref name=CDC>{{cite web | title = West Nile Virus | url = http://wwwnc.cdc.gov/eid/article/10/1/pdfs/02-0616.pdf }}</ref><ref name="pmid12890319">{{cite journal| author=Miller DL, Mauel MJ, Baldwin C, Burtle G, Ingram D, Hines ME et al.| title=West Nile virus in farmed alligators. | journal=Emerg Infect Dis | year= 2003 | volume= 9 | issue= 7 | pages= 794-9 | pmid=12890319 | doi=10.3201/eid0907.030085 | pmc=PMC3023431 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12890319 }} </ref><ref name="pmid16704810">{{cite journal| author=Bakonyi T, Ivanics E, Erdélyi K, Ursu K, Ferenczi E, Weissenböck H et al.| title=Lineage 1 and 2 strains of encephalitic West Nile virus, central Europe. | journal=Emerg Infect Dis | year= 2006 | volume= 12 | issue= 4 | pages= 618-23 | pmid=16704810 | doi=10.3201/eid1204.051379 | pmc=PMC3294705 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16704810 }} </ref><ref name="pmid14585341">{{cite journal| author=Charrel RN, Brault AC, Gallian P, Lemasson JJ, Murgue B, Murri S et al.| title=Evolutionary relationship between Old World West Nile virus strains. Evidence for viral gene flow between Africa, the Middle East, and Europe. | journal=Virology | year= 2003 | volume= 315 | issue= 2 | pages= 381-8 | pmid=14585341 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14585341 }} </ref><ref name="pmid12093177">{{cite journal| author=Lanciotti RS, Ebel GD, Deubel V, Kerst AJ, Murri S, Meyer R et al.| title=Complete genome sequences and phylogenetic analysis of West Nile virus strains isolated from the United States, Europe, and the Middle East. | journal=Virology | year= 2002 | volume= 298 | issue= 1 | pages= 96-105 | pmid=12093177 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12093177 }} </ref><ref name="pmid21781205">{{cite journal| author=Papa A, Xanthopoulou K, Gewehr S, Mourelatos S| title=Detection of West Nile virus lineage 2 in mosquitoes during a human outbreak in Greece. | journal=Clin Microbiol Infect | year= 2011 | volume= 17 | issue= 8 | pages= 1176-80 | pmid=21781205 | doi=10.1111/j.1469-0691.2010.03438.x | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21781205 }} </ref><ref name="pmid22406344">{{cite journal| author=Savini G, Capelli G, Monaco F, Polci A, Russo F, Di Gennaro A et al.| title=Evidence of West Nile virus lineage 2 circulation in Northern Italy. | journal=Vet Microbiol | year= 2012 | volume= 158 | issue= 3-4 | pages= 267-73 | pmid=22406344 | doi=10.1016/j.vetmic.2012.02.018 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22406344 }} </ref><ref name="pmid21586266">{{cite journal| author=Valiakos G, Touloudi A, Iacovakis C, Athanasiou L, Birtsas P, Spyrou V et al.| title=Molecular detection and phylogenetic analysis of West Nile virus lineage 2 in sedentary wild birds (Eurasian magpie), Greece, 2010. | journal=Euro Surveill | year= 2011 | volume= 16 | issue= 18 | pages= | pmid=21586266 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21586266 }} </ref>
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| * Lineage 1: Widespread, isolates from Europe, America, Middle East, India, Africa, and Australia
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| * Lingeage 2: Southern Africa, Madagascar, and Europe
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| ==Natural reservoir==
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| Although WNV can infect humans and numerous animals, birds are its main [[natural reservoir]].<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><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>
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| ==Gallery==
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| <gallery>
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| Image: Flavivirus13.jpeg| West Nile virus is a flavivirus commonly found in Africa, West Asia, and the Middle East. <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
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| Image: Flavivirus12.jpeg| This is a transmission electron micrograph (TEM) of the West Nile virus (WNV). <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
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| </gallery>
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| Image: Flavivirus06.jpeg| Digitally-colorized transmission electron micrograph (TEM) of the West Nile virus (WNV). <SMALL><SMALL>''[http://phil.cdc.gov/phil/home.asp From Public Health Image Library (PHIL).] ''<ref name=PHIL> {{Cite web | title = Public Health Image Library (PHIL) | url = http://phil.cdc.gov/phil/home.asp}}</ref></SMALL></SMALL>
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| </gallery>
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| ==References==
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| {{Reflist|2}}
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| ==[[West nile virus pathophysiology|Pathophysiology]]== | | ==[[West nile virus pathophysiology|Pathophysiology]]== |