International Committee on Taxonomy of Viruses
The International Committee on Taxonomy of Viruses ( ICTV ) (International Committee for the Taxonomy of Viruses ) is since 1971 a panel of currently about 500 virologists within the International Union of Microbiological Societies. It works on the standardization and organization of taxonomic names of viruses, viroids, virusoids, prions and retrotransposons.
Activity
The work of this independent body is required if a new virus is discovered and to be associated with an internationally valid name. In addition, the ICTV is concerned with the systematic renaming of virus groups and their classification into genera, families and orders. The reports and findings of the ICTV are binding on the scientific naming and thus form the official Virus taxonomy.
The ICTV taxonomy includes instantaneously 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 its critics, as regularly fail attempts by the ICTV, yet still common in publications names (mostly by explorers or places named) against systematic exchange names, eg Human herpesvirus 4 ( Epstein -Barr virus) or HHV 3 ( varicella- zoster virus ). A recent example of a Namensgebungskonfliktes was the SARS virus, which was isolated almost simultaneously in Asia, America and Europe of patients with the same disease in 2003. It initially circulated depending discoverer different names. The assigned by ICTV name " SARSCoV " includes on the one hand the disease (SARS ) virus genus (co) coronavirus and "V" for the virus.
In 1986 was the uniform naming of a special virus of great importance: from the synonymous terms: LAV, HTLV -III, ARV and a number of individual names decided the ICTV taxon HIV for " Human Immunodeficiency Virus " ( Human Immune weakness virus).
Objectives of the ICTV
The official objectives of the ICTV are ( according to the current 8th Report of the ICTV 2004):
- Development of an internationally accepted taxonomy
- Development of generally accepted names for taxa of viruses and subviral pathogens
- Development of species lists and taxonomic Internet Database ( ICTVdB )
Taxonomic rules
The virological nomenclature should in principle have a certain traceable stability, thereby preventing the risk of confusion and ambiguities of taxa and avoid unnecessary names creations. For the international designation of a species the English name applies. Proper names and numbering in conjunction with individual letters should be avoided. Genera have the ending- virus, subfamilies - virinae, Family viridae and orders - viral. Taxa are always written in italics and with the correct ending.
On the classification of subviral pathogens are to be applied in principle the rules for viruses. The species name for viroids should end in- viroid, whose genera - viroid, subfamilies - viroinae and Family viroidae. Retrotransposons of the taxonomy are considered with respect to viruses; for satellites and prions relatively free taxonomy is still allowed, allow a clear taxonomy to further discoveries.
Taxonomy and Phylogeny
Due to the diversity of viruses and the controversies about their evolution, the taxonomy no phylogenetic lines represents the view that viruses come from very different systems of nucleic acids and proteins of eukaryotic and prokaryotic cells, can also be a clear classification in evolutionary biology clear relationships very restricted to. The virus taxonomy is not monophyletic. This is one of the reasons why the taxonomy breaks usually already at the level of the family, often of the order.
Even so taxonomically important criteria such as the genome or the presence of a shell are not criteria to accept or exclude relationships. Thus, the acquisition or further drop an envelope with a change of the host may be phylogenetically possible to have as well as the packaging of different nucleic acids during replication to the emergence of RNA viruses from DNA viruses, and vice versa out (example: Representatives of Hepadnaviridae family, at it can be assumed that a packaging of the DNA stage an original RNA virus ).