Dictionary > Virus


noun, plural: viruses
A submicroscopic infectious agent that is unable to grow or reproduce outside a host cell. It is non-cellular but consisting of a core of DNA or RNA surrounded by a protein coat.
A virus requires a living cell for it to grow and reproduce similar to an obligate intracellular parasite. Many viruses can cause disease in host organisms but not all can cause disease. The first known virus, tobacco mosaic virus, was discovered by Martinus Beijerinck in 1899.
Viruses may be classified based on their type of genome (Baltimore classification):

Word origin: Latin virus meaning toxin or poison.
See also: virology, viroid, bacteriophage.
Related terms:

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