Genus is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.
Order is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes. An immediately higher rank, superorder, is sometimes added directly above order, with suborder directly beneath order. An order can also be defined as a group of related families.
Virus classification is the process of naming viruses and placing them into a taxonomic system similar to the classification systems used for cellular organisms.
Podoviridae was a family of bacteriophage in the order Caudovirales often associated with T-7 like phages. The family and order Caudoviraleshave now been abolished, with the term podovirus now used to refer to the morphology of viruses in this former family. There were 130 species in this family, assigned to 3 subfamilies and 52 genera. This family was characterized by having very short, noncontractile tails. Many former phages in the former family Podoviriade are now classified in the Autographiviridae
Closteroviridae is a family of viruses. Plants serve as natural hosts. There are four genera and 59 species in this family, seven of which are unassigned to a genus. Diseases associated with this family include: yellowing and necrosis, particularly affecting the phloem.
Fiersviridae is a family of positive-strand RNA viruses which infect prokaryotes. Bacteria serve as the natural host. They are small viruses with linear, positive-sense, single-stranded RNA genomes that encode four proteins. All phages of this family require bacterial pili to attach to and infect cells. The family has 185 genera, most discovered by metagenomics. In 2020, the family was renamed from Leviviridae to its current name.
Luteoviridae was a family of viruses. The family was abolished in 2020 based on evidence that its three genera and seven species unassigned to a genus belonged to two other, existing families.
The International Committee on Taxonomy of Viruses (ICTV) authorizes and organizes the taxonomic classification of and the nomenclature for viruses. The ICTV develops a universal taxonomic scheme for viruses, and thus has the means to appropriately describe, name, and classify every virus taxon. The members of the International Committee on Taxonomy of Viruses are considered expert virologists. The ICTV was formed from and is governed by the Virology Division of the International Union of Microbiological Societies. Detailed work, such as identifying new taxa and delimiting the boundaries of species, genera, families, etc. typically is performed by study groups of experts in the families.
The Herpesvirales is an order of dsDNA viruses with animal hosts, characterised by a common morphology consisting of an icosahedral capsid enclosed in a glycoprotein-containing lipid envelope. Common infections in humans caused by members of this order include cold sores, genital herpes, chickenpox, shingles, and glandular fever. Herpesvirales is the sole order in the class Herviviricetes, which is the sole class in the phylum Peploviricota.
Globuloviridae is a family of hyperthermophilic archaeal viruses. Crenarchaea of the genera Pyrobaculum and Thermoproteus serve as natural hosts. There are four species in this family, assigned to a single genus, Alphaglobulovirus.
Hypovirus is a genus of viruses, in the family Hypoviridae. Fungi serve as natural hosts. There are four species in this genus. Infection reduces the virulence of its parasitic host, making it a hyperparasite useful for blight control.
Alphaflexiviridae is a family of viruses in the order Tymovirales. Plants and fungi serve as natural hosts. There are 65 species in this family, assigned to six genera. Diseases associated with this family include: mosaic and ringspot symptoms.
Secoviridae is a family of viruses in the order Picornavirales. Plants serve as natural hosts. There are 8 genera and 86 species in this family, one of which is unassigned to a genus. The family was created in 2009 with the grouping of families Sequiviridae, now dissolved, and Comoviridae, now subfamily Comovirinae, along with the then unassigned genera Cheravirus, Sadwavirus, and Torradovirus.
Tevenvirinae is a subfamily of viruses in the family Straboviridae of class Caudoviricetes. The subfamily was previously placed in the morphology-based family Myoviridae, which was found to be paraphyletic in genome studies and abolished in the 2021 International Committee on Taxonomy of Viruses (ICTV) classification. Bacteria and archaea serve as natural hosts. There are 148 species in this subfamily, included in 14 genera.
Ackermannviridae is a family of viruses in the class Caudoviricetes. Gammaproteobacteria in the phylum Pseudomonadota serve as natural hosts. There are two subfamilies, ten genera, and 63 species in the family.
Herelleviridae is a family of bacterial viruses of the order Caudovirales infecting members of the phylum Firmicutes. The family has five subfamilies, 33 genera and 92 species.
Ribozyviria is a realm of satellite nucleic acids — infectious agents that resemble viruses, but cannot replicate without a helper virus. Established in ICTV TaxoProp 2020.012D, the realm is named after the presence of genomic and antigenomic ribozymes of the Deltavirus type. The agents in Ribozyviria are satellite nucleic acids, which are distinct from satellite viruses in that they do not encode all of their own structural proteins but require proteins from their helper viruses in order to assemble. Additional common features include a rod-like structure, an RNA-binding "delta antigen" encoded in the genome, and animal hosts. Furthermore, the size range of the genomes of these viruses is between around 1547–1735nt, they encode a hammerhead ribozyme or a hepatitis delta virus ribozyme, and their coding capacity only involves one conserved protein. Most lineages of this realm are poorly understood, the notable exception being the genus Deltavirus, comprising the causal agents of hepatitis D in humans.
Straboviridae is a family of bacteriophages in the class Caudoviricetes. The viruses in this family were formerly place in the morphology-based family Myoviridae, which was found to be paraphyletic in genome studies and abolished in the 2021 International Committee on Taxonomy of Viruses (ICTV) classification, although the term myovirus is still used to refer to the morphology of viruses in this new family. Bacteria and archaea serve as natural hosts. There were 209 species in this family, assigned to 36 genera and three subfamilies.
Kyanoviridae is a family of bacteriophages in the class Caudoviricetes. The viruses in this family were formerly place in the morphology-based family Myoviridae, which was found to be paraphyletic in genome studies and abolished in the 2021 International Committee on Taxonomy of Viruses (ICTV) classification, although the term myovirus is still used to refer to the morphology of viruses in this new family. Bacteria and archaea serve as natural hosts. There are currently 66 species in this family, assigned to 54 genera.
