West nile virus

Jump to navigation Jump to search

For patient information click here.


This page is about clinical aspects of the disease.  For microbiologic aspects of the causative organism(s), see West nile virus.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Michael Maddaleni, B.S.

Synonyms and keywords: West Nile, WNV

Overview

Historical Perspective

This page is about microbiologic aspects of the organism(s).  For clinical aspects of the disease, see West nile virus.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]

Overview

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.

Taxonomy

Viruses; ssRNA viruses; ssRNA positive-strand viruses, no DNA stage; Flaviviridae; Flavivirus; Japanese encephalitis virus group[1]

Biology


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.[2]

The WNV has an icosahedral symmetry, with a smooth surface.[3] 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.[4] 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.

  • Structural proteins are responsible for the formation of the viral particle and include:
  • Envelope proteins
  • Membrane proteins
  • C proteins
  • Non-structural proteins are responsible for viral replication, evasion of the immune system, and assembly of virions. They include:
  • NS1
  • NS2A
  • NS2B
  • NS3
  • NS4A
  • NS4B
  • NS5

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.[5][6][7][8][9][10][11][12]

  • Lineage 1: Widespread, isolates from Europe, America, Middle East, India, Africa, and Australia
  • Lingeage 2: Southern Africa, Madagascar, and Europe

Natural reservoir

Although WNV can infect humans and numerous animals, birds are its main natural reservoir.[2][4]

Gallery

Image: Flavivirus06.jpeg| Digitally-colorized transmission electron micrograph (TEM) of the West Nile virus (WNV). From Public Health Image Library (PHIL). [13]

</gallery>

References

  1. ↑ "West Nile Virus".
  2. ↑ 2.0 2.1 Petersen LR, Brault AC, Nasci RS (2013). "West Nile virus: review of the literature". JAMA. 310 (3): 308–15. doi:10.1001/jama.2013.8042. PMID 23860989.
  3. ↑ Mukhopadhyay, S. (2003). "Structure of West Nile Virus". Science. 302 (5643): 248–248. doi:10.1126/science.1089316. ISSN 0036-8075.
  4. ↑ 4.0 4.1 Campbell, Grant L; Marfin, Anthony A; Lanciotti, Robert S; Gubler, Duane J (2002). "West Nile virus". The Lancet Infectious Diseases. 2 (9): 519–529. doi:10.1016/S1473-3099(02)00368-7. ISSN 1473-3099.
  5. ↑ "West Nile Virus" (PDF).
  6. ↑ Miller DL, Mauel MJ, Baldwin C, Burtle G, Ingram D, Hines ME; et al. (2003). "West Nile virus in farmed alligators". Emerg Infect Dis. 9 (7): 794–9. doi:10.3201/eid0907.030085. PMC 3023431. PMID 12890319.
  7. ↑ Bakonyi T, Ivanics E, Erdélyi K, Ursu K, Ferenczi E, Weissenböck H; et al. (2006). "Lineage 1 and 2 strains of encephalitic West Nile virus, central Europe". Emerg Infect Dis. 12 (4): 618–23. doi:10.3201/eid1204.051379. PMC 3294705. PMID 16704810.
  8. ↑ Charrel RN, Brault AC, Gallian P, Lemasson JJ, Murgue B, Murri S; et al. (2003). "Evolutionary relationship between Old World West Nile virus strains. Evidence for viral gene flow between Africa, the Middle East, and Europe". Virology. 315 (2): 381–8. PMID 14585341.
  9. ↑ Lanciotti RS, Ebel GD, Deubel V, Kerst AJ, Murri S, Meyer R; et al. (2002). "Complete genome sequences and phylogenetic analysis of West Nile virus strains isolated from the United States, Europe, and the Middle East". Virology. 298 (1): 96–105. PMID 12093177.
  10. ↑ Papa A, Xanthopoulou K, Gewehr S, Mourelatos S (2011). "Detection of West Nile virus lineage 2 in mosquitoes during a human outbreak in Greece". Clin Microbiol Infect. 17 (8): 1176–80. doi:10.1111/j.1469-0691.2010.03438.x. PMID 21781205.
  11. ↑ Savini G, Capelli G, Monaco F, Polci A, Russo F, Di Gennaro A; et al. (2012). "Evidence of West Nile virus lineage 2 circulation in Northern Italy". Vet Microbiol. 158 (3–4): 267–73. doi:10.1016/j.vetmic.2012.02.018. PMID 22406344.
  12. ↑ Valiakos G, Touloudi A, Iacovakis C, Athanasiou L, Birtsas P, Spyrou V; et al. (2011). "Molecular detection and phylogenetic analysis of West Nile virus lineage 2 in sedentary wild birds (Eurasian magpie), Greece, 2010". Euro Surveill. 16 (18). PMID 21586266.
  13. ↑ 13.0 13.1 13.2 "Public Health Image Library (PHIL)".

Pathophysiology

Epidemiology & Demographics

Risk Factors

Screening

Differentiating West nile virus from other Diseases

Natural History, Complications & Prognosis

Diagnosis

History & Symptoms | Physical Examination | Lab Tests | Case Studies

Treatment

Medical Therapy | Primary Prevention | Future or investigational therapies

Related Chapters

Resources


Template:WS

Retrieved from "https://www.wikidoc.org/index.php?title=West_nile_virus&oldid=1130339"