Ebola Virus paper - Microbiology

Topics: Immune system, Virus, Antibody Pages: 5 (1272 words) Published: November 14, 2013
Introduction

Ebola virus which causes Ebola hemorrhagic fever, was first recognized in 1976 in Zaire, now Democratic Republic of Congo, and Sudan. It is named after the river Ebola in Zaire. The virus has five known subtypes named after the location where they were first identified and caused disease: Ebola Sudan, Ebola-Bundibugyo, Ebola-Zaire, Ebola-Ivory Coast and Ebola-Reston. (CDC.gov) Ebola-Reston is the newest subtype and was identified in research macaques imported from Philippines to Virginia in 2004 and later in Texas in 2006. It was discovered that the research animals in both cases were from the same site in the Philippines where guinea pigs were also found to have been infected with the same strain. (CDC.gov) While Ebola-Ivory Coast and Ebola-Reston do infect humans, symptoms as manifested by infection with other subtypes is not seen nor have any human deaths been reported. (Lee and Saphire, 2009) Ebola-Zaire and Ebola-Sudan are the most lethal with mortality rates upwards of 90% and 61% respectively. (CDC.gov)

Ebola virus is classified as a Class A bioterrorism agent and one that must be handled bio- safety level 4 labs. Research of Ebola virus requires trained professionals and facilities with rigorous levels of control to access. (CDC.gov) Like other viruses, the survival and spread of Ebola is dependent upon the host organism. At this time, the natural reservoir is not known which complicates containment and prevention of acquisition of Ebola. There are hypotheses that a non-primate is the host organism. Recent research points to fruit bats as the possible host carriers as the virus and viral antibodies are found in them though they do not exhibit any symptoms. Research continues in attempting to discover the natural reservoir so transmission prevention mechanisms may be implemented. The virus is not known to be native to continents other than Africa and Philippines in Asia. (CDC.gov) Ebola virus poses a considerable public health concern due to recent emergence of new subtype, high mortality rate associated with it, concern of possible misuse of the virus and lack of antiviral or vaccines. (Sarwar, 2011)

Pathophysiology

Ebola virus belongs to the Filoviridae family of viruses which also includes the very similar Marburg virus. It is an enveloped virus and is characterized by a long filamentous structure which can present as straight, branched, circular or folded strand with a uniform diameter of approximately 80 nm but variable in length. It specifically targets, endothelial cells, liver cells, neutrophils and macrophages. Infected cells produce large amount of cytokines which solicits a huge response from the immune system and disrupts normal behavior of liver, kidneys, respiratory system, skin and blood. (Hammer, 2012)

“Ebola virus is a non-segmented negative strand RNA genome containing 7 structural and regulatory genes. The Ebola genome contains four virion structural proteins and three membrane associated proteins.” (CDC.gov)The viral non structural secretory glycoprotein, sGP, is produced in large quantities early in infection. This glycoprotein binds to neutrophil receptor and inhibits its activation and the body's innate immune response at large. A non secretory envelope glycoprotein, GP, binds to endothelial cells but not to neutrophils. “It is known to destroy endothelial cells which is associated with disseminated intravascular coagulation. This may contribute to the hemorrhagic manifestations of Ebola.” (Lee and Cook, 2013) The receptor of host cell on which the glycoprotein attaches to is still being researched. The virus enters the host cells through endocytosis where it replicates and synthesizes its proteins. It exits the cell with host cell membrane including its proteins enveloped around it. (Lee and Cook, 2013)

Ebola virus is classified as zoonotic as transmission of it can be from animals to humans. It can also be...

Bibliography: Cook JD, Lee JE The Secret Life of Viral Entry Glycoproteins: Moonlighting in Immune Evasion. PLoS Pathog May 2013 volume 9 issue 5
Hammer J The hunt for Ebola: in Uganda, a CDC team races to find the origins of a deadly virus. Smithsonian. November 2012 volume 43 issue 7: 24
Lee JE, Saphire EO Ebolavirus glycoprotein structure and mechanims of entry. Future Virol. 2009 volume 4 issue 6: 621-635
Sarwar UN, Sitar S, Ledgerwood JE Filovirus emergence and vaccine development: a perspective for health care practitioners in travel medicine. Travel Med Infect Dis. May 2011 volume 9 issue 3:126-34
http://www.mayoclinic.com/health/ebola-virus/DS00996
http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/Fact_Sheets/Ebola_Fact_Booklet.pdf
http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/ebola/ebolatable.htm
http://emedicine.medscape.com/article/216288-overview
http://www.who.int/csr/disease/ebola/en/
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