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Classification and Nomenclature of Viruses

Seventh Report of the International Committee on Taxonomy of Viruses

Edited By
M.H.V. van Regenmortel, C.M. Fauquet, D.H.L. Bishop
E.B. Carstens, M.K. Estes, S.M. Lemon, J. Maniloff, M.A. Mayo, D. J. McGeoch, C.R. Pringle, R.B. Wickner

Virology Division
International Union of Microbiological Sciences

This report describes the taxa and viruses approved by the ICTV between 1970 and 1999. Descriptions of the most important characteristics of these taxa are provided, together with a list of species and tentative species and selected references. These descriptions represent the work of the chairpersons and members of the subcommittees and study groups of the ICTV. A glossary of abbreviations and terms is provided first, followed by a set of virus diagrams per type of host and listings of the taxa by type of nucleic acid and size of the genome.

The names of orders, families, subfamilies, genera and species approved by the ICTV are printed in italics. Names that have not yet been approved are printed in quotation marks in standard type. Tentative species names, strain, serotype, genotype and isolate names are printed in standard type.

Throughout the Report, three categories of viruses of the various taxa have been defined: (1) Type species: pertains to the type species used in defining the taxon. As noted above, the choice of the type species by ICTV is not made with the kind of precision that must be used by international specialty groups and culture collections or when choosing substrates for vaccines, diagnostic reagents, etc. In this regard, the designation of prototype viruses and strains must be seen as a primary responsibility of international specialty groups. (2) Other species: pertains to those viruses which on the basis of all present evidence definitely belong to the taxon. (3) Tentative species: pertains to those viruses for which there is presumptive but not conclusive evidence favoring membership of the taxon.

The ICTV has approved 3 orders, 56 families, 9 subfamilies, 233 genera and 1550 virus species. Descriptions of virus satellites, viroids and the agents of spongiform encephalopathies (prions) of humans and several animal and fungal species are included. Finally, a list of unassigned viruses is provided with a pertinent reference for each.