Viruses : A Infectious Agent That Replicates Only Inside The Living Cells Of Other Organisms

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A virus is a microscopic infectious agent that replicates only inside the living cells of other organisms. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. A 2013 study done by Center for Infection and Immunity, Mailman School of Public Health at Columbia University in New York estimates that there are over 320,000 mammalian viruses. There are many different ways to contract a virus including: airborne, bodily fluids and ingestion. Once the virus enters your body it goes through five stages of infection: absorption, penetration phase, replication, assembly, and release.
The first phase is the absorption or attachment phase. During this phase the virus attachment sites bind to one or more of the receptors on the host cells’ plasma membrane to infect. Each host cell contains a specific receptor site or sites that the virus binds to. If the host cell does not contain the right receptor site then the virus will not be able to attach and therefore the host will not get infected. The host cell could also contain antibodies, which block the virus from attaching. Plant viruses can only attach to plant cells, which is why animals do not get the same viruses as plants (Introduction to Viruses).
The second phase is the entry or penetration phase. During the entry phase the host cell literally absorbs or “swallows” the virus via endocytosis or fusion host. After it absorbs the virus the enzymes digest viral capsid to

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