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Virus - Encyclopedia.WorldSearch (Site not responding. Last check: 2007-08-10) |
 | | It has also been suggested that they may represent extremely reduced microbes, appeared separately in the primordial soup that gave rise to the first cells, or that the different sorts of viruses appeared through different mechanisms. |
 | | Other infectious particles which are even simpler in structure than viruses include viroids, virusoids, and prions. |
 | | Examples of diseases caused by viruses include the common cold, which is caused by any one of a variety of related viruses; smallpox; AIDS, which is caused by HIV; and cold sores, which are caused by herpes simplex. |
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