Devin Camenares & Roger Nussbaum Comparative Virology 9/30/05
n n West Nile Virus (WNV) is a relative new virus of the family Flaviviridae genus Flavivirus and It is a positive sense single strand RNA virus WNV is an arbovirus, which infects mostly birds, but also humans and other animals It is transmitted by Mosquitoes
n n WNV has a genome of ~11 kbp, consisting of one huge ORF, which is cleaved into smaller protiens pr. M and E (envelope) proteins are used in serological identification and phylogenetic comparison of different WNV strains Strucutral Proteins Genome illustration from the CDC, Envelope protein structure from Purdue
n n First recorded case of WNV was an adult woman in Uganda, 1937 Neuroinvasive properties recognized during an outbreak in Israel, 1957 First appearance on the Western Hemisphere occurred in New York City, 1999 WNV reaches Mexico, Canada, the Caribbean and West Coast USA, 2003
n n WNV strain NY-99 shared 99. 8% homology with a 1998 isolate in Israel, and 96% homology with Romanian isolate Only 75% homology with the related Kunjin virus and the WNV Nigerian strain Homology compares 1278 bp region of envelope and structural proteins Antigenic characterization provide further evidence Data and tree from Lanciotti, et all (1999).
n n Broad host range including humans, birds, horses, deer, dogs, cats, squirrles, bats, mosquitoes, ticks WNV can exist as quasispecies because it mutates very quickly In 1999 it was noted that WNV had already begun to microevolve In 2003 a study on Long Island found that mosquitoes support a genetically diverse population of WNV
n n n RT-PCR is a common method for detecting the presence of WNV in mosquitos and dead birds Immunoglobin M captured ELISA Viral cell culture People are encouraged to submit deceased birds to local township animal controls for testing Mosquito traps are set up in order to gain more samples
Map from CDC’s West Nile Virus page
n For 2005, there have so far been 696 severe cases (40%), 993 mild cases, and 115 unspecified cases of WNV; a total of 1804 cases nation wide. There have been 52 deaths (~3% mortality) Data and map from the CDC’s West Nile Virus page
Diagram from Gould and Fikrig (2004).
n n There are currently no specific treatments for WNV Vaccinations for WNV are a work in progress For now, the WNV is only controlled through mosquito spraying and education of the public The best defense on a personal level is to use DEET-based repellents before you go outside in the morning or evening
n n n R. S. Lanciotti, et al. (1999) Origin of the West Nile Virus Responsible for an Outbreak of Encephalitis in the Northeastern United States. Science, Vol 286, Issue 5448, p 2333 -2337 G. Jerzak, et al. (2005) Genetic Variation in West Nile virus from natural infected mosquitoes and birds suggests quasispecies structure and strong purifying selection. J. Gen. Virol. (86), p 2175 -2183 http: //jcm. asm. org/cgi/content/full/38/11/4066 - virus detection http: //www. cdc. gov/ncidod/dvbid/westnile/map. htm - world distribution map http: //www. cdc. gov/ncidod/dvbid/westnile/surv&control 05 Maps. htm - national distribution map http: //en. wikipedia. org/wiki/West_Nile_Virus - wikipedia west nile virus article
Скачать презентацию Devin Camenares Roger Nussbaum Comparative Virology 9 30 05
5d32f869b59b5ad73de6ffafa59d177e.ppt