VARIOLA VIRUS Essay examples -- Essays Papers

VARIOLA VIRUS SMALLPOX INTRODUCTION The Variola virus, which is the most virulent member of Genus Orthopoxvirus, is the causative agent of smallpox. It specifically infects humans. The primary reason for infection in humans is due to its ability to evade the host immune responses, and avoid complement activation. Over the centuries, this naturally occurring virus has spread throughout the earth, through various environments, to cause severe outbreaks. The most devastation outbreak had a case-fatality rate of 40 percent in individuals who have not been vaccinated. The Variola virus is a double-stranded DNA virus. It has two envelopes: the outer envelope is present only in the extracellular state. The outer surface or the core membrane, which surrounds the core of the virus, contains lipids and proteins and has a complex symmetry. The core, which has a dumbbell-shape, contains a large amount of the double-stranded DNA (186kbp), about 10 enzymes to mediate gene expression and lots of nucleoproteins- both specific and common. These proteins are involved in DNA transcription, as well as inducing cross-reactive immunity (IOM, 1999). The space outside the core contains lateral bodies – which do not have any known functions. There are two forms of the variola virus: variola major and variola minor. Variola major is the lethal strain, while variola minor is not lethal, but a mild strain, which is very similar to major but is only genetically different. The most common strain is the variola major, which produces the more severe symptoms, and with a fatality rate of 20% to 40%, within the 7th day of infection. The variola minor is the milder form of the disease that has a death rate of less than 1%. Surviving infection from... ...o, Pere, MD. "Smallpox: The Triumph Over the Most Terrible of the Ministers of Death." Annals of Internal Medicine. 1997; 127:635- 42. Ellner, P.D. "Smallpox: Gone but Not Forgotten." Infection. 1998; 26 (5); 263-9. CDC overview: www.bt.cdc.gov/agent/smallpox/vaccination/facts.asp CDC overview2: www.bt.cdc.gov/agent/smallpox/overview/disease-facts.asp CDC vaccine : www.bt.cdc.gov/agent/smallpox/vaccination/contraindictions-public.asp Koplow, David. "Smallpox: The Fight to Eradicate a Global Scourge. 2003 IOM(Institute of Medicine): "Live Variola Virus – committee on the assessment of future Scientific needs for live variola virus. National Academy Press; 1999. Mayo Foundation for Medical Education and Research (MFMER). October 1, 2002 http://www.mayoclinic.com/invoke.cfm?id=ds00424 Nature Reviews Immunology 2, 544 (2002); doi:10.1038/nri868