International Committee on Taxonomy of Viruses
The International Committee on Taxonomy of Viruses ( ICTV , International Committee for the Taxonomy of Viruses ) has been a body of currently around 500 virologists within the International Union of Microbiological Societies since 1971 . It works on the standardization and organization of taxonomic names of viruses , viroids , virusoids , prions and retrotransposons . The forerunner of the ICTV was the International Committee on Nomenclature of Viruses (ICNV) which emerged on the occasion of the 9th International Congress for Microbiology in Moscow in 1966 from the provisional Committee for the Nomenclature of Viruses of the International Association of Microbiological Societies (IAMS), which had existed since 1963 .
activity
The work of this independent body is called for when a new virus is discovered and an internationally valid name is assigned to it. In addition, the ICTV is concerned with the systematic renaming of virus groups and their division into genera, families and orders. The reports and specifications of the ICTV are binding for the scientific designation and thus form the official virus taxonomy .
The ICTV taxonomy currently includes three orders, 73 families, 9 subfamilies, 287 genera and more than 5450 viruses in more than 1950 species.
The work of the ICTV is not without critics, so attempts by the ICTV to continue to exchange common names in publications (mostly named after discoverers or places) for systematic names, e.g. B. Human herpes virus 4 ( Epstein-Barr virus ) or HHV 3 ( varicella zoster virus ). A recent example of a naming conflict was the SARS virus, which was isolated almost simultaneously in Asia, America and Europe from patients with the disease of the same name in 2003 . Initially, different names circulated depending on the discoverer. The name “SARS-CoV” assigned by the ICTV includes the disease (SARS), the virus family (Co) Coronaviridae and “V” for virus.
In the year 1986 was the consistent naming of a special virus of great importance: from the synonymous terms: LAV, HTLV-III, ARV, and a number of individual names, the ICTV decided the taxon HIV for "Human Immunodeficiency Virus" (Human Immune Weakness virus).
Goals of the ICTV
The official objectives of the ICTV are (according to the valid 8th Report of the ICTV 2004 ):
- Development of an internationally recognized taxonomy
- Development of generally accepted names for taxa of viruses and subviral pathogens
- Publication of taxonomic decisions
- Creation of species lists and a taxonomic internet database (ICTVdB)
Taxonomic rules
The virological nomenclature should in principle have a certain comprehensible stability, avoid the risk of confusion and ambiguity of taxa and avoid unnecessary creation of names. At the same time, the taxonomy should represent phylogenetic relationships as correctly as possible. The first basic rules (especially the departure from the bacteriological system), according to which all viruses should be recorded, were drawn up in 1975. Previously there were different taxonomic systems for bacteriophages, plant viruses and animal viruses.
The English name applies to the international name of a species. Proper names and numbering in connection with individual letters are to be avoided. Genera have the ending -virus , subfamilies -virinae , families -viridae and orders -virales . Taxa must always be written in italics (with the exception of orders) and with the correct ending.
In principle, the rules for viruses should also be applied to the classification of subviral pathogens. The species name for viroids should end in -viroid , their genera -viroid , subfamilies -viroinae and families -viroidae . Retrotransposons are considered viruses for taxonomy; a relatively free taxonomy is allowed for satellites and prions until further discoveries allow a clear taxonomy.
Taxonomy and Phylogeny
Due to the diversity of viruses and the controversies about their evolution , the taxonomy does not represent genealogical lines. The view that viruses originate from very different systems of nucleic acids and proteins, from eukaryotic and prokaryotic cells, allows a clear classification into evolutionary-biological clear relationships only very much restricted to. The virus taxonomy is therefore not monophyletic . This is one of the reasons why the taxonomy usually breaks off at the family level and rarely the order.
Even taxonomically important criteria such as the genome or the presence of a shell are not criteria to assume or exclude relationships. The acquisition or renewed loss of an envelope when the host changes, for example, can be genetically possible, just as the packaging of different nucleic acids during replication led to the development of RNA viruses from DNA viruses and vice versa (example: representatives of the Hepadnaviridae family , at packaging of the DNA stage of an original RNA virus can be assumed).
Triva
On May 8, 2015, the World Health Organization (WHO) published a statement in which guidelines for naming newly discovered infectious diseases and their pathogens were formulated. According to WHO information, some names have led to unintended negative consequences in the past, for example by provoking unjustified traffic and travel hindrances, restrictions on trade or the unjustified culling of farm animals. Members of certain ethnic or religious groups would have suffered disadvantages as a result. The Middle East Respiratory Syndrome (MERS) and " swine flu " were named as examples . The naming of new diseases and infectious agents must therefore be carried out with great care, since once common names have been introduced it is difficult to remove them from public use. Virus names, if derived from the diseases they cause, should be descriptive and describe the disease in generic expressions (e.g. respiratory, neurological, diarrhea ...), combined with suitable attributes (severe, progressive, juvenile, wintry ...). On the other hand, expressions should be avoided (all following examples from the WHO declaration) that refer to geographical conditions (e.g. Middle East respiratory syndrome , Spanish flu , Rift Valley fever ), as well as expressions with personal names (e.g. Creutzfeldt-Jakob Disease , Chagas disease ), animal species or food names (e.g. swine flu, avian flu , monkey pox ), or cultural, ethnic, population, or occupational expressions (e.g. Legionnaires' disease ). Expressions that could inappropriately trigger fears (“unknown”, “fatal”, “epidemic”) should also be avoided.
literature
- CM Fauquet, MA Mayo et al .: Eighth Report of the International Committee on Taxonomy of Viruses , London, San Diego, 2005
- Authors of the ninth ICTV report: Virus Taxonomy - Classification and Nomenclature of Viruses . Ed .: Andrew MQ King, Michael J. Adams, Eric B. Carstens, Elliot J. Lefkowitz et al. (= International Committee on Taxonomy of Viruses [Ed.]: ICTV Reports . 9th report). Elsevier - Academic Press, Amsterdam / Boston / Heidelberg / London / New York / Oxford / Paris / San Diego / San Francisco / Singapore / Sydney / Tokyo 2012, ISBN 978-0-12-384684-6 (English, 1344 pp., Google Books [accessed June 12, 2020]).
- Authors of the ninth ICTV report: Virus Taxonomy - Classification and Nomenclature of Viruses. Online edition. In: ICTV Reports . International Committee on Taxonomy of Viruses, 2011, accessed on June 12, 2020 (English, parallel archived on April 2, 2019 on web.archive.org .).
Web links
Individual evidence
- ^ Frank Fenner : The Nomenclature and Classification of Viruses - The International Committee on Nomenclature of Viruses . In: Journal of General Virology . tape 13 , no. 2 , November 1, 1971, doi : 10.1099 / 0022-1317-13-2-iv (English).
- ^ Frank Fenner: The classification and nomenclature of viruses. Summary of results of meetings of the International Committee on Taxonomy of Viruses in Madrid, September 1975 . J. General Virol. (1976) 31 (3): pp. 463-70 PMID 819628
- ^ WHO issues best practices for naming new human infectious diseases. World Health Organization, May 8, 2015, accessed February 6, 2020 .