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glossary:virus [2007/09/08 05:00]
Pat O'Connor
glossary:virus [2012/10/16 14:40] (current)
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 +A microorganism smaller than a [[bacteria]],​ which cannot grow or reproduce apart from a living [[cell]]. A virus invades living cells and uses their chemical machinery to keep itself alive and to replicate itself. It may reproduce with fidelity or with errors (mutations)-this ability to mutate is responsible for the ability of some viruses to change slightly in each infected person, making treatment more difficult.
 +Viruses cause many common human [[infection]]s,​ and are also responsible for a bevy of rare [disease]]s. Examples of viral illnesses range from the common cold, which is usually caused by one of the [[rhinoviruse]]s,​ to [[acquired immunodeficiency syndrome]] (AIDS), which is caused by the [[human immunodeficiency virus]] (HIV).
 +Viruses may contain either [[DNA]] or [[RNA]] as their [[genetic]] material. Herpes simplex virus and the hepatitis- B virus are DNA viruses. RNA viruses have an enzyme called reverse transcriptase that permits the usual sequence of DNA-to-RNA to be reversed so the virus can make a DNA version of itself. RNA viruses include HIV and the hepatitis C virus.
 +Researchers have grouped viruses together into several major families, based on their shape, behavior, and other characteristics. These include the [[herpesvirus]]es,​ [[adenovirus]]es,​ papovaviruses (papilloma viruses), hepadnaviruses,​ poxviruses, and parvoviruses among the DNA viruses. On the RNA virus side, major families include the picornaviruses (including the rhinoviruses),​ calciviruses,​ paramyxoviruses,​ orthomyxoviruses,​ rhabdoviruses,​ filoviruses,​ bornaviruses,​ and retroviruses. There are dozens of smaller virus families within these major classifications. Many viruses are host-specific,​ causing disease in humans or specific animals only. 
 +The Dutch microbiologist Martinus Beijerinck (1851-1931) was the first person to use the term "​virus"​ for the invisible disease-causing material that he showed to be self-replicating.
glossary/virus.txt ยท Last modified: 2012/10/16 14:40 (external edit)