Tuesday, 3 April 2012

Scientists Discover Storable Ebola Vaccine


Scientists Discover Storable Ebola Vaccine
Description: Ebola virus (Credit: SPL)
Ebola hemorrhagic fever (EHF) is a disease caused by the Ebola virus (EBOV), resulting in influenza-like symptoms, hemorrhaging (bleeding) and frequently death in humans and primates. Since first being identified in Northern Zaire, 1976 (World Health Organization 1978, pp. 271-3), EHF has been the cause of approximately 1500 reported deaths (Center For Disease Control and Prevention, 2011). While cases of EHF are infrequent and it's death toll small in comparison to other diseases, the virus has an extremely high mortality rate (50-90% depending on the strain) and can be spread through contact with an infected individual (Center For Disease Control and Prevention, 2011). Because of this, EBOV poses a serious threat to global wellbeing as these qualities give it potential for mass destruction if deployed as a bioweapon by terrorists, or simply spread through infection. In order to prevent this, a vaccine or a cure to this deadly disease has been the objective of
large amounts of research over the last few decades.
Text Box: Image of EBOV (Carpenter, J)Until recently, the few vaccines that had been produced, and that have shown some degree of effectiveness against EHF, have been unable to survive storage, degrading and becoming ineffective at immunizing patients. However, a newly developed vaccine has the ability to survive longer periods of time in storage, potentially making it a viable vaccine for storage in the event of EBOV outbreak.
Unlike previous vaccines, which have relied on the injection of weakened EBOV particles, causing an immune response (Carpenter, J, 2011), the newly created vaccine instead uses glycoproteins, material from the outer layer of the Ebola virus (Chimes, A. 2011). The glycoproteins of the EBOV are introduced to a culture containing monoclonal antibodies, which recognise the glycoprotein as being a threat and fuse with it, producing Ebola Immune Complexes (EICs) (Phoolcharoen, W et.al., 2011). In this way, the antibody is tricked into elicting an immune response, whereupon the immune complexes formed by this can be used to the bodies advantage. This, when used in conjunction with the Toll-like receptor 3 agonist ('pattern-recognition receptors that have key roles in detecting microbes and initiating inflammatory responses' (Underhill, D.M., Ozinsky, A. 2002)) known as PIC, was found to initiate an effective immune response, resulting in 80% of mice vaccinated using EICs and PIC surviving large doses of EBOV (30,000 LD50 of mouse adapted virus) (Phoolcharoen, W et.al., 2011). These results indicate that the immune responses elicited by the mice were aided by the EICs and PIC they were vaccinated with.
In conclusion, while the vaccine has only been proven to work on mice, the discovery of a vaccine capable of long-term storage could allow nations to stockpile large amounts of the vaccine cost effectively if it can be adapted to work on humans. This is because supplies of the vaccine do not constantly need replenishing as they are not degrading like previous vaccines. This would also mean that nations with access to the vaccine are somewhat secure against outbreaks, as there is an effective vaccine that can be readily dispersed. However, a 20% mortality rate for a disease when vaccinated is still high, and thus further research into more effective vaccines could prove to be beneficial.




References:
Carpenter, J. 2011, 'Vaccine Developed against Ebola', BBC News, 6 December, viewed 17 March 2012, <http://www.bbc.co.uk/news/science-environment-16011748>
Centers for Disease Control and Prevention 2011, Known Cases and Outbreaks of Ebola Hemorrhagic Fever, in Chronological Order, U.S. Department of Health and Human Services, USA, Washington, D.C., viewed 17 March 2012, <http://www.cdc.gov/ncidod/dvrd/spb/mnpages/dispages/ebola/ebolatable.htm>
Chimes, A. 2011, 'New Ebola Vaccine Proves Effective in Mice', Voice of America, 9 December, Viewed 17 March 2012 <http://www.voanews.com/english/news/health/New-Ebola-Vaccine-Proves-Effective-in-Mice-135314653.html>
Phoolcharoen, W, Dye, J. M., Kilbourne, J., Piensook, K., Pratt, W. D., Arntzen, C. J., Chen, Q., Mason, H. S., Herbst-Kralovetz, M. M. 2011, 'A nonreplicating subunit vaccine protects mice against lethal Ebola virus challenge' Proceedings of the National Academy of Science, vol. 108, no. 51, viewed 17 March 2012, <http://www.pnas.org/content/108/51/20695.short>
Underhill, D.M., Ozinsky, A. 2002, 'Toll-like receptors: key mediators of microbe detection', Current Opinion in Immunology, vol. 14, no. 1, viewed 17 March 2012, http://www.sciencedirect.com/science/article/pii/S0952791501003041
World Health Organization 1978, 'Ebola haemorrhagic fever in Zaire', 1976, Bulletin of the World Health Organization, 56 (2): pp. 271-3, viewed 17 March 2012,  <http://whqlibdoc.who.int/bulletin/1978/Vol56-No2/bulletin_1978_56(2)_271-293.pdf>

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