West nile virus causes: Difference between revisions

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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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West Nile viruses can be designated into at least 5 phylogenetic lineages.15 Only lineage 1 and 2 West Nile viruses have been associated with significant outbreaks in humans.


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  
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  

Revision as of 14:36, 11 September 2014

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Taxonomy

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

Biology

Digitally-colorized transmission electron micrograph (TEM) of the West Nile virus (WNV). Image provided by the CDC Centers for Disease Control and Prevention [2]
Presence of West Nile virus virions, in an isolate that was grown in a cell culture. Image provided by the CDC Centers for Disease Control and Prevention [3]

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.[4] 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.[5] 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.

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

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.[6]

Structure

Tropism

Natural Reservoir

Natural reservoirs of the West Nile virus include:[7]

  • Humans
  • 65 different species of mosquitos
  • 326 species of birds




References

  1. ↑ "West Nile Virus".
  2. ↑ "http://phil.cdc.gov/phil/details.asp". External link in |title= (help)
  3. ↑ "http://phil.cdc.gov/phil/details.asp". External link in |title= (help)
  4. ↑ Mukhopadhyay, S. (2003). "Structure of West Nile Virus". Science. 302 (5643): 248–248. doi:10.1126/science.1089316. ISSN 0036-8075.
  5. ↑ 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.
  6. ↑ "West Nile Virus" (PDF).
  7. ↑ 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.
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