Comment: Ratified changes will be published in Virology Division News in Archives of Virology, and in subsequent ICTV Reports.
Comment: see section 3.8
Comments: It is not obligatory to use all levels of the taxonomic hierarchy. The primary classification is of viruses into species. Most species are classified into genera and most genera are classified into families. Species not assigned to a genus will be "unassigned" in a family (see Rule 3.6) and genera not classified in families have the status of "unassigned" (sometimes referred to as "floating"). Some families are classified together into Orders, but for many, the family is the highest level taxon in use. Also, families are not necessarily divided into subfamilies. This taxon is to be used only when it is needed to solve a complex hierarchical problem (see Rule 3.29).
Contrasting examples of full classifications of some negative strand RNA viruses are:- (1) species Mumps virus; genus Rubulavirus; subfamily Paramyxovirinae; family Paramyxoviridae; order Mononegavirales, and (2) species Rice stripe virus; genus Tenuivirus (see also Rule 3.41).
Comments: Particular virus isolates may be regarded as strains, variants, clusters or other subspecific entities that, together with other entities, constitute a species. Classification of such isolates is not the responsibility of the ICTV but is the responsibility of international specialty groups. It is the responsibility of ICTV Study Groups to decide if an isolate or a group of isolates should constitute a species.
Deciding the names of serotypes, genotypes, strains, variants or isolates of virus species is not the responsibility of the ICTV. However, it is recommended that new names not be the same as, or closely similar to, names already in use (Rule 3.14 for taxa). When a particular virus isolate is designated to represent a species, the decision as to which name will be adopted for the species for formal taxonomic purposes will be the responsibility of the ICTV, usually based on recommendations of a particular Study Group working on behalf of the ICTV. The Study Group will be expected to consult widely so as to ensure the acceptability of names, subject to the Rules in the Code. The policy of the ICTV is that as far as is possible, decisions on questions of taxonomy and nomenclature should reflect the majority view of the appropriate virological constituency.
Comments: Naturally occurring isolates that have genomes formed from parts of the genomes of different strains of a virus, either by recombination between genome nucleic acids or by re-assortment of separate genome parts, will be classified either as species or subspecific entities in the same way that other isolates are classified. Neither artificial variants made by recombination or re-assortment nor mutant viruses are subject to the Rules in the Code.
Comments: A species can be classified as an unassigned member of a family when no genus has been devised. For example, Bimbo virus is a rhabdovirus of vertebrates but is not a member of any of the currently recognised genera in the family Rhabdoviridae. Likewise, Groundnut rosette assistor virus resembles viruses in the family Luteoviridae but is not classified in any of the genera in that family. These viruses are each classified as an unassigned member of their respective families.
Comments: Taxa above the rank of species must be approved before a name is assigned to them. Proposals for the creation of taxa shall be accompanied by proposals for names. A decision to create a taxon can thus be followed immediately by a decision about the name for the taxon. Species will be approved together with their names as a single taxonomic act.
The following example is of a proposal concerning an imaginary virus with the vernacular name of "beta gamma virus" that is related to another virus, "alpha beta virus".
II - Rules about naming Taxa
Comments: A valid name is one that has been published, one that is associated with descriptive material, and one that is acceptable in that it conforms to the Rules in the Code. Accepted names will be kept in an "Index" by the ICTV.
Comment: A stable nomenclature is one of the principal aims of taxonomy and therefore changes to names that have been accepted will only be considered in exceptional circumstances, and then only because of serious conflict with the Rules.
Comments: The earlier of candidate names for a taxon may be chosen as a convenience to virologists, but the Rule ensures that it is not possible to invalidate a name in current use by claiming priority for an older name that has been superceded.
Comments: New taxon names shall not be made by adopting a person's name, by adding a formal ending to a person's name or by using part of a person's name to create a stem for a name. When existing names of species incorporate a person's name (for example, Shope papilloma virus) continued usage of this name, in agreement with Rule 2.3 and 3.9, is in general preferable to the creation of a new name.
Comments: In general, short names are desirable and the number of syllables should be kept to a minimum.
Comments: The Rule is intended to make text unambiguous and easy to manipulate and its application should often make names more pronouncable, in agreement with Rule 3.12. Existing names of some species violate this Rule (e.g. Enterobacteria phage ?), but international names of genera and families do not.
Comments: The name selected for a new taxon should not sound indistinguishable from the name of another taxon at any rank or from any taxon. For example, the existence of the genus Iridovirus means that forms of new name such as "irodovirus" or "iridivirus" are unacceptable as they are too easily confused with an approved name. Confusion can also be between species and genus names as both end in "virus". Thus, for example, the name selected for a genus typified by a species "Omega virus" would not be named "Omegavirus" because species and genus would then be too readily confused.
Comments: Sigla are names comprising letters and/or letter combinations taken from words in a compound term. The name of the genus Comovirus has the sigla stem "Co-" from cowpea and "-mo-" from mosaic; the name of the genus Reovirus has the sigla stem "R" from "Respiratory, "e" from "enteric" and "o" from "orphan".
Comments: When there is more than one candidate name for the same taxon, the decision as to which will be accepted shall be made on the basis of the Code and, if necessary, thereafter on the basis of likely acceptability to the majority of virologists.
Comments: Occasionally the names proposed for taxa are judged unsuitable and revisions are requested. To facilitate the classification into appropriate taxa, it is preferable to accept the creation of a taxon with a temporary name rather than delay. Temporary names are indicated by quotation marks and the type species name is used. For example, Soybean chlorotic mottle virus is the type species in an as yet un-named genus in the family Caulimoviridae. Until the genus is named, it is designated as "soybean chlorotic mottle-like viruses". This designation is regarded as temporary.
Comments: Proposals concerning a family containing genera of viruses that infect diverse types of host (eg plants and vertebrates, fungi and plants, and so on) must be considered by the Subcommittees responsible for viruses of each host type (ie Plant viruses, Vertebrate viruses, and so on). For example, taxonomic proposals concerned with the family Partitiviridae would be considered by the Fungal Virus Subcommittee and one of its Study Groups but because some genera in the family contain viruses of plants, proposals affecting the family would also be considered by the Plant Virus Subcommittee.
Comments: Species classified as tentative are candidates for taxonomic decision by the appropriate Study Groups to resolve their tentative status.
Comments: Species names normally comprise more than one word. The styles used when virus names are devised differ according to the traditions of the particular fields of virology. For example, plant virus names are usually constructed as host + symptom + "virus" (e.g. tobacco necrosis virus) whereas, in contrast, viruses in the family Bunyaviridae are usually named after the location at which the virus was found + "virus" (e.g. Bunyamwera virus).
Comments: Species names should be distinctive. They should not be in a form that could be easily confused with the names of other taxa.
Comments: The existence of species names such as Bovine adenovirus A, Bovine adenovirus B, and so on, and Human herpesvirus 1, Human herpesvirus 2, Human herpesvirus 3, and so on justify the use of the next number in the series. A name such as “22” or “A7” is not acceptable.
Comments: For example, the species Potato spindle tuber viroid is classified in genus Pospiviroid, and the family Pospiviroidae.
Comments: See Rule 3.8 for the definition of an "accepted" name.
Comments: When used formally, as labels for taxonomic entities, the names "Tobacco mosaic virus" and "Murray River encephalitis virus" are in the correct form and typographical style. Examples of incorrect forms are Aspergillus niger virus S (not italic), Murray river encephalitis virus (River is a proper noun) or tobacco mosaic virus (not capitalized or italic).
Taxa are abstractions and thus when their names are used formally, these are written distinctively using italicization and capitalization. In other senses, such as an adjectival form (e.g. the tobacco mosaic virus polymerase) italics and capital initial letters are not needed. Equally, these are not needed when referring to physical entities such as virions (e, g. a preparation or a micrograph of tobacco mosaic virus).
This Rule was introduced in 1998 and is in contradistinction to Rules in the Code published in the 6th ICTV Report.
Comments: For example, the correct formal descriptions of various taxa are ... the family Herpesviridae ... the genus Morbillivirus, ....the genus Rhinovirus, ....the species Tobacco necrosis virus, and so on.