virus

This article is about the type of pathogen. For the type of malware, see  Computer virus . For other uses, see  Virus (disambiguation) . For a more accessible and less technical introduction to this topic, see  Introduction to viruses . Viruses Rotavirus Virus classification Group: I–VII Groups 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  archaea . [1] Since  Dmitri Ivanovsky 's 1892 article describing a non-bacterial  pathogen  infecting tobacco plants, and the discovery of the  tobacco mosaic virus ...