does a virus have cells

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** Virus **

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This article is about the pathogen. For other uses, see Virus
For a more accessible and less technical introduction to this topic, see
Introduction to viruses.

Rotavirus Reconstruction.jpg
Virus classification
Group: I–VII
I: dsDNA viruses
II: ssDNA viruses
III: dsRNA viruses
IV: (+)ssRNA viruses
V: (−)ssRNA viruses
VI: ssRNA-RT viruses
VII: dsDNA-RT viruses

A *virus* is a small 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

Since Dmitri Ivanovsky's 1892 article describing a non-bacterial pathogen
infecting tobacco plants, and the discovery of the tobacco mosaic virus by
Martinus Beijerinck in 1898,^[2] about 5,000 virus species have been
described in detail,^[3] although there are millions of different
types.^[4] Viruses are found in almost every ecosystem on Earth and are the
most abundant type of biological entity.^[5]^[6] The study of viruses is
known as virology, a sub-speciality of microbiology.

While not inside an infected cell or in the process of infecting a cell,
viruses exist in the form of independent particles. These *viral
particles*, also known as *virions*, consist of two or three parts: (i) the
genetic material made from either DNA or RNA, long molecules that carry
genetic information; (ii) a protein coat, called the capsid, which
surrounds and protects the genetic material; and in some cases (iii) an
envelope of lipids that surrounds the protein coat when they are outside a
cell. The shapes of these virus particles range from simple helical and
icosahedral forms for


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