Microbiology Biology 299
9/18/2015

West Nile Virus

The height of the summer months brings high temperatures in late afternoons. We are all smacking, swatting and spraying - knowing it’s that time of year for mosquitoes. Mosquito bites are a nuisance. Many people fear contracting the West Nile Virus. A virus is described as “a genetic element that contains either RNA or DNA and that replicate only in host cells; has an extracellular form.” (Brock Biology of Microorganism’s) A virus is also an ultramicroscopic infectious agent which replicates itself only within cells of living hosts. (Webster Dictionary) Along with being classified as a virus West Nile shows that it only infects certain and specific cells [Secondary Source]. Since Dmitri Ivanovsky's 1892 article describes a non-bacterial pathogen infecting tobacco plants, and the discovery of the tobacco mosaic virus by Martinus Beijerinck in 1898, about 5,000 viruses have been described in detail. [Secondary Source] Although there are millions of different types, viruses also undergo cycles in order to reproduce and harm and/or help organisms. There are two types of viral cycles known to men, the lytic cycle and the lysogenic cycle. In the lytic cycle the virus attaches itself to the host cell and nucleic acid is inserted into the cell. Next it makes copies of DNA and capsid and more viruses are assembled. Finally the viruses are released by bursting the cell and destroying it. The lysogenic cycle is slightly different than the first cycle only by a few characteristics. During the lysogenic cycle the virus also attaches and inserts nucleic acid into the cell, but instead of creating new viruses and let them be released, viral DNA is made along with the cell's DNA. That is called Provirus and the nucleic acid replicates with the cell. After that the cell can go to the lytic cycle at any time. While in the lysogenic cycle, the virus is said to be dormant. [Secondary Source]. Viruses are found in almost every ecosystem on Earth and are the most abundant type of biological entity. The study of viruses are known as virology, a sub-specialty of microbiology. Science shows that viruses cannot replicate unless the virion itself or its genome gain entry into a suitable host cell which known as the process of infection. Further studies state that the anatomy makeup of a virus also has an outer core called the Capsid. There is an envelope of lipids that surround the protein coat when they are outside a cell. The shapes of viruses range from simple helical and icosahedral forms to more complex structures. The average virus is about one one-hundredth the size of the average bacterium. With this core, it determines the shape of the virus and has an inner core that is made up nucleic acid [Secondary Sources]. Most viruses are too small to be seen directly with an optical microscope. The origins of viruses in the evolutionary history of life is unclear: some may have evolved from plasmids – pieces of DNA that can move between cells – while others may have evolved from bacteria. In evolution, viruses are an important means of horizontal gene transfer, which increases genetic diversity Viruses are considered being one key characteristic to what makes life entity because they carry important genetic materials that helps in reproduction and form things to be able to evolve in this world of evolution. However, they lack cell structure which is considered necessary to count as life. Because they possess some but not all such qualities, viruses have been described as "organisms at the edge of life". Viruses spread in many ways as they often do in plants. Characteristics of antibiotics aren’t harmful to viral diseases so the decision in this case is preventing diseases with vaccination, this then produces immunity. The characteristics that establish life are all living things are made up of cells, all grow and reproduce based on heritable info from DNA, all evolve and all require input of energy. Viruses are not considered alive even though they contain RNA or DNA they need a host cell to reproduce. Viruses are not cells and cannot evolve or use energy. Bacterium is a prokaryotic cell; it can reproduce, and uses the input of energy. Bacterium also evolves as certain resistances to antibiotics. [Secondary Source].
There are many diseases caused by viruses and the one of many is West Nile Virus. Though this virus does not have a high mortality rate, when the virus initially surfaced it caused huge pandemonium, and fear around the country [3]. With more knowledge about the virus and what steps could be taken to reduce the risk of contraction, society began to take better precautions. High risk of contraction are especially alarming for those who spend a lot of time outside, as they are more prone mosquito bites. As the epidemic of the West Nile Virus continue to spread from one community to the next, the health care systems are being challenged now more than ever to take the necessary measures to prevent the wide-spread distribution of the virus. We now have scientific knowledge that mosqioto’s are indeed the source and carrier of this virus. Within the past decade, West Nile Virus has become one of many emerging diseases. In 1999 the United States has also been a part of the new countries where this virus has emerged. Although the West Nile Virus (WN) has been around since 1937 when it was first discovered in Uganda, the summer of 1999 marks the first introduction in recent history of an Old World flavivirus into the New World. It is closely related to St. Louis encephalitis virus found in the United States. West Nile virus is a part of the Baltimore classification in group 4 which contains the positive sense stranded RNA viruses [1]. This was developed by David Baltimore, is a virus classification system that groups viruses into families, depending on their type of genome (DNA, RNA, single-stranded (ss), double-stranded and their method of replication.[Secondary Source] “West Nile Virus is considered a positive sense stranded RNA genome that belongs to the family called flavivirus which is the yellow fever and dengue virus that contains an enveloped capsid containing a plus-sense. This virus can invade the nervous system of its warm blooded hosts, which include some species of both birds and mammals [1]. Understanding that this is a flavivirus it is found in Africa, West Asia, and the Middle East. The size of this family of viruses usually has a range from 25-60nm, but West Nile Virus is about 25-30nm long. When the host is infected the course of action that the virus takes onto human infection with West Nile Virus is through the bite of an infected mosquito. Mosquitos become infected by feeding on infected birds, which circulate the virus in their blood for roughly five to ten days. The virus gets into the mosquito’s salivary glands. One bitten by a mosquito, the virus gets into humans and animals, where it can multiply and possibly cause illness. Scientific notion of this is that the West Nile Virus is an enveloped, + strand RNA virus, which goes through certain life cycles of replication, and it uses ribosomes, and other components of the host cell to help in its replication. West Nile Virus has a particular cell tropism for monocytes derivatives, macrophages, and dendritic cells that the virus begins replicating by attaching to an unknown cell receptor using the E protein of the virus. Next, West Nile Virus enters the cell via endocytosis. A vaccine has yet to be developed in treating patients and protecting those from West Nile Virus. Many scientists are working on this issue, and there is hope that a vaccine will become available in the future but right now there is the only help for severe cases. Antibiotics will not cure West Nile Virus because it is not a bacterial disease. Most people (70-80%) who become infected with West Nile virus do not develop any symptoms. According to the CDC about one in five people who are infected will develop a fever. Other symptoms that are neurologic illnesses can include headache, body aches, joint pains, vomiting, diarrhea, or rash. Some may even develop inflammation of the brain or surrounding tissues and may cause death [1]. Most people with this type of West Nile virus recover completely. However, fatigue and weakness could last for weeks or months. Therefore, it is recommended that residents take precautions through preventive measures to avoid getting mosquito bites.
West Nile Virus health impact only comes around every few years and the Georgia Department of Public Health states that the virus is not as big of an uproar as the public has caused. Locally they have reported just this year two cases were found in South Augusta and one was found in Central Augusta. Those that tested positive for West Nile Virus was in the ages of fifty-seven, eighty-seven, and sixty-two. According to the Georgia Department of Public Health steps are being taken in reducing the mosquito population within the affected areas by the Richmond County Mosquito Program which includes spraying the areas, conducting walk-through by technicians to identify mosquito populations. The department says once all steps are completed, there will be a re-evaluation period [5]. Those who are not part of the high risk group are using insect repellents when outdoors. Repellents containing DEET, picaridin, IR3535, and some oil of lemon eucalyptus and para-menthane-diol products provide longer-lasting protection and reducing the number of mosquitoes around your home. The good news is that the government has contributed funds to be able to get further research in controlling the outbreak. With governmental foundations they are providing grants to our local swap, Phinizy Swamp, so that they trap mosquitoes and send them off for testing for the West Nile Virus (WNV) [5]. Records show that it is sixty-five species of mosquitoes in the state of Georgia and twenty-four in Richmond County. It is difficult to try in pinpoint which ones might be carrying this deadly disease. Along with their findings it is found that they can they lay hundreds of eggs a day. Female mosquito can lay anywhere from seventy-five to one-hundred and fifty eggs five times a day and when that water disappears the eggs are still viable up to 4 years but when they get wet again they’ll start hatching. The rainy weather we’ve been having has brought out old and new eggs that are now able to hatch in the damp climates [5]. A vaccine has yet to be developed in treating patients and protecting those from West Nile Virus.

Work Cited: 1. Centers for Disease Control and Prevention http://www.cdc.gov/ncidod/dvbid/westnile/q&a.htm 2. The Ochsner Journal West Nile Virus: An Historical Overview James J. Sejvar, MD http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3111838/ 3. Children’s Healthcare of Atlanta-Reviewed by: Steven Dowshen, MD
Date reviewed: August 2009 http://www.choa.org/child-health-glossary/w/we/west-nile-virus_kh_parent 4. Georgia Department of Agriculture Gary Black, Commissioner http://www.agr.georgia.gov/Data/Sites/1/media/ag_animalindustry/animal_health/files/wnvqa.pdf RICHMOND CO., Ga. (WRDW) -- The Georgia Public Health Laboratory confirms several human cases of West Nile Virus in Richmond County. 5. Secondary Sources:
Brock Biology of Microorganisms 14th Edition. Madigan et. Al. Published by Pearson.
Webster dictionary