THE INTERNATIONAL COMMITTEE ON TAXONOMY OF VIRUSES ADOPTS A BINOMIAL NOMENCLATURE FOR VIRUS SPECIES

The International Committee on Taxonomy of Viruses (ICTV), formerly the International Committee on Nomenclature of Viruses, founded in 1966, is responsible for developing and maintaining an internationally agreed system of hierarchical classification of viruses and naming of taxa. The advancements in virus taxonomy are made available to the scientific community through a website (https://talk.ictvonline.org) and published reports/papers. Over the years the ICTV has adapted its taxonomic framework to reflect current knowledge on the evolution of global virosphere. In particular, the ICTV now allows the classification of viruses known only from genomic data. Taxonomic ranks have been expanded beyond orders, paving the way to comprehensive studies on evolutionary connections of viruses. A "megataxonomy" approach was established, unifying all currently classified RNA viruses in the realm Riboviria, whereas ssDNA and dsDNA viruses were afterwards classified into the realms Monodnaviria, Varidanaviria and Duplodnaviria. The expansion of taxonomic ranks brings virus taxonomy closer to other biological taxonomies. Species naming in all these taxonomies follow a Latinized binomial format (i.e., binomial nomenclature) first introduced by Carl Linnaeus in 1753, consisting of two italicized words indicating the genus ("genus name") and the species ("specific name/species epithet"), respectively. Typical examples of binomial species names are Arabidopsis thaliana, Saccharomyces cerevisiae, Homo sapiens, and Escherichia coli. In contrast, viral species names did not follow a uniform format, except for a requirement to be italicized and to have the first letter of the first word capitalized. The ICTV recognized the need for a standardized nomenclature and, after years of internal discussions, in 2020 launched a call for public discussion and feedback on adopting a uniform binomial momenclature. Following open debates, a binomial nomenclature for virus species has been ratified by the ICTV in the 2021 vote. Thus, a virus species name will consist of two (and only two) italicized words, the first one being the genus name and the second one consisting of a "free-form" species epithet. In this framework, Linnaean-style, Latinized virus species are permitted, but not mandated. The species names can be composed using the standard Latin-script English alphabet containing 26 letters and/or Arabic numbers. Importantly, this change in nomenclature will apply to virus species only. Common virus names (for example human immunodeficiency virus 1, tobacco mosaic virus, grapevine virus A, etc) will not be affected and will remain unchanged.