Keeping up with virus taxonomy

Posted on July 16, 2018   by Laura Cox

As sequencing technologies continue to become more efficient, more and more viruses are being discovered. Until recently, classification of these new viruses still relied upon information about physical properties. The ICTV has since embraced metagenomics, using sequence data to infer biological properties and define new viruses. 

The International Committee on Taxonomy of Viruses (ICTV) is responsible for developing and maintaining a universal virus taxonomy. Known viruses are categorised into a classification scheme taking into consideration their evolution.

At the American Society for Virology’s 37th Annual Meeting, the ICTV hosted the satellite session ‘A World of Viruses: Exploding Diversity and its Impact on Classification.’ Here, they discussed whether the current methods used to define viral species are still relevant, if we should change them, and how.

ICTV Taxonomy profiles are published in the Journal of General Virology and provide concise overviews of the classification, structure and properties of virus orders, families and genera. Over the coming months, Microbe Post will be investigating the families published as ICTV Taxonomy Profiles, as well as continuing the discussion on the changing field of taxonomy.

Flaviviridae is a family of viruses including 89 different species. These viruses are spherical and can infect mammals and birds. Members of the genus Flavivirus are usually transmitted by insect vectors, such as mosquitoes.

Some Flaviviruses you might have heard of:

  • dengue virus
  • hepatitis C virus
  • West Nile virus
  • bovine viral diarrhoea virus

Pneumoviridae used to be a sub-family within the Paramyxoviridae family but was re-classified in 2016. There are five virus species in Pneumoviridae, members of which infect humans, birds and certain mammals. Viruses in this family are responsible for the majority of cases of pneumonia and bronchiolitis in young children, while other viruses cause respiratory infections in birds.

The Picornaviridae family contains 94 species, isolates of which are small viruses, capable of infecting a range of hosts including humans. There are many important virus species in this family, including the first animal virus ever to be discovered: foot-and-mouth disease virus (FMDV). FMDV was discovered in 1897 by Friedrich Loeffler and is a highly infectious virus of major importance in farming.

Thanks to funding from the Wellcome Trust, two-page summaries of each chapter of the ICTV report (a free resource published by the ICTV which provides an up-to-date description of virus taxonomy) are to be made freely available in the Journal of General Virology. These summaries are known as ICTV Virus Taxonomy Profiles and describe the structure, replication and taxonomy of each virus order and family.