Genomics Revolution

Guest Hosts: Alysa Giudici & Rachel Jerkins

Episode 50: West Nile Fever

 

Script:

Rachel: Hey everybody, and welcome to another episode of Genomics Revolution. This is Rachel Jerkins and Alysa Giudici (Guh-Dee-Cee), here to talk about the West Nile Virus. 

 

Rachel: The West Nile Virus comes from the flavivirus genus and the family flaviviridae. In 1937, the virus was first discovered in the West Nile area of Uganda in Africa. It is a single-stranded RNA virus around 11kbp in size with stem loops on the 5’ and 3’ ends. The genome codes for 10 proteins— 3 for structure in the coding region, plus seven not in the new virus structure from the non-coding region. 

 

Rachel: The West Nile Virus causes a disease called West Nile fever (Richter et al. 2017). It is believed to spread when a mosquito bites an infected bird and then bites a person. It wasn’t until 1999 that the virus made its first appearance in the western hemisphere (White et al., 2001). It is crucial to study the disease because it can be a fatal neurological disease and has now spread across a majority of the globe.It is believed to be the main cause of viral encephalitis around the world (Chancey et al. 2015) 

 

Alysa: Thanks Rachel, Since the sequencing of the genome, there are many key findings that have emerged. The virus thrives utilizing a vector-virus relationship. The entry of the WNV is through receptor mediated endocytosis once the virus attaches to the cell surface (Colpitts et al.) Interestingly, the virus was able to be tracked through an enzootic cycle involving Culicidae mosquitoes and birds. The birds act as a form of host reservoirs allowing the virus is amplified through the bird – mosquito – bird cycle, until the fall when female mosquitoes begin to “bite” humans. Although many external factors can contribute to the amplification cycle, the disease does exist in multiple habitats (Peterson, 2002). This form of transmission causes the virus to transmit quickly and effectively. 

 

Alysa: The apparent symptoms appear to be anorexia, nausea, vomiting, eye pain, headache, etc. that last roughly 3-6 days (Peterson, 2002). These symptoms eventually, if untreated became neurological and possibly deadly. After research, it was determined that there are, however, two lineages of the West Nile Virus. The 1st lineage is the one that is known to affect humans. Not only is the West Nile Virus detrimental to humans, but it is also a leading neurologic disease in many animals such as the equine population. Further sequencing of this genome and Reverse transcription-PCR has further educated the veterinary world as well. Recent evidence acquired by Venter et al. in horses suggests that the lineage 2 strains are highly neuroinvasive in humans and mice. A disease that we continue to fight in humans is also a disease we will continue to fight in animals as well. Who would have guessed that? Thanks for listening.

 

Works Cited:

Richter, J., C. Tryfonos, A. Tourvas, D. Floridou, N. Paphitou, and C. Christidoulou (2017).

Complete genome sequence of West Nile virus (WNV) from the first human case of neuroinvasive WNV infection in Cyprus. Amer. Soc. for Microbio. 5(43) 1-2. Doi: 10.1128/genomeA.01110-17

 

Chancey, C., A. Grinev, E. Volkova, and M. Rios. (2015). The global ecology and epidemiology of West Nile virus. BioMed Res. Int. 376230. Doi: 10.1155/2015/376230

 

White, D. J., Kramer, L. D., Backenson, P. B., Lukacik, G., Johnson, G., Oliver, J., … Campbell, S. (2001). Mosquito Surveillance and Polymerase Chain Reaction Detection of West Nile Virus, New York State. Emerging Infectious Diseases, 7(4), 643–649. doi: 10.3201/eid0704.017407 

 

Petersen, L. R., & Marfin, A. A. (2002). West Nile Virus: A Primer for the Clinician. Annals of Internal Medicine, 137(3), 173. doi: 10.7326/0003-4819-137-3-200208060-00009

 

Colpitts, T. M., Conway, M. J., Montgomery, R. R., & Fikrig, E. (2012). West Nile Virus: Biology, Transmission, and Human Infection. Clinical Microbiology Reviews, 25(4), 635–648. doi: 10.1128/cmr.00045-12 

 

Venter, M., Human, S., Zaayman, D., Gerdes, G. H., Williams, J., Steyl, J., Leman, P. A., Paweska, J. T., Setzkorn, H., Rous, G., Murray, S., Parker, R., Donnellan, C., & Swanepoel, R. (2009). Lineage 2 west nile virus as cause of fatal neurologic disease in horses, South Africa. Emerging infectious diseases, 15(6), 877–884. https://doi.org/10.3201/eid1506.081515