Abstract
More than 30 years have elapsed since the first report of the International Committee on Taxonomy of Viruses (ICTV) was published in 1971. Since that publication, the ICTV recognizes about 1,550 virus species, but some 30,000 virus strains and isolates are being tracked by virologists in different fields of biology. The ICTV is the 'international court' of experts that rules on names and relationships of all virus, but only to the level of species. Virus taxonomy is changing rapidly, with changes ranging from the trivial(use of italics for species names) to profound reorganization driven by the explosion of sequence information. The universal system of viral taxonomy now accepts Linnean-like classification at the levels of order, family, subfamily, genus, and species. The suffix '-virales' identifies an order, Families are identified by the suffix '-viridae' subfamilies are identified by the suffix '-virinae', and genera are identified by the suffix '-virus'. The importance of distinguishing subspecies, strains, and isolates in vaccine development, diagnostics, etc. is recognized, but these lower levels are not formally classified by ICTV. This paper mainly introduces taxonomy and classification of animal viruses on the basis of the seventh report of the ICTV edited by Van Regenmortal et al. in 2000.