Keeping up with Virus Taxonomy: virus families that are transmitted or maintained in insects
Posted on July 26, 2024 by Clare Baker
For this edition of 'Keeping up With Virus Taxonomy' we're looking at some interesting families that contain viruses that are transmitted or maintained in insects.
Fimoviridae
This family of spherical viruses is transmitted to plants by mites in the Eriophyidae family. They infect mainly dicotyledonous species (such as fig, kiwi, grapevine and pistachio) and a few monocotyledonous species (wheat, maize, ti). One example of the Fimoviridae family is the fig mosaic virus, which is where the family earns its name. Depending on the host, infection by this virus varies from leaf mottling, vein clearing (loss of green colour in plant veins), chlorotic ringspots (ring-shaped spots) and sterility of flowers to a general mosaic.
Phasmaviridae
This is a family of seven genera: Cicadellivirus, Feravirus, Hymovirus, Jonvirus, Orthophasmavirus, Sawastrivirus, and Wuhivirus. They infect and are maintained in insects such as Hemiptera, an order of insects called true bugs; Diptera, an order of flies that includes mosquitoes and hoverflies; and the order Hymenoptera which include wasps, bees and ants. This family’s name comes from phantom midges — hosts of the first described viruses of the family.
Nairoviridae
This family of viruses also contains seven genera. They’re maintained and/or transmitted by arthropods among birds and mammals. Norwaviruses and orthonairoviruses (genuses within the Nairoviridae family) are the only viruses in this family that are known to cause disease. Members of the genus Orthonairovirus are transmitted to mammals by argasid or ixodid ticks and their hosts include verspertillionid bats, murid rodents and the critically endangered pangolin. The most important human orthonairovirus with public-health impact is CCHFV, which is tick-borne and endemic in much of Asia, Africa and Southern and Eastern Europe. It often causes severe and frequently fatal viral haemorrhagic fever.
Spinareoviridae
This family includes viruses that have relatively large spikes or turrets at the 12 icosahedral vertices of the virion or core particle. The Spinareoviridae family have a large host range, including mammals, aquatic animals, birds, reptiles, fungi, plants and of course arthropods. Their name, Spinareoviridae derives from the latin word ‘spina’, meaning ‘spike’ referencing the spikes or turrets on the surface of the core particles.
Sedoreoviridae
In contrast to the spikey appearance of the Spinareoviridae family, the family Sedoreoviridae are relatively smooth and lack large surface projections on the subviral particle, giving them a smooth appearance. They’re closely related to Spinareoviridae and belong to the same order - Reovirales. A typical member of this family is the Rotavirus A species which is responsible for the majority of seasonal endemic diarrheal disease in young children and can also infect other mammals. Another genus in the family, Seadornavirus, are transmitted to vertebrate hosts by mosquito vectors.
Kolmioviridae
Finally, we have the Kolmioviridae family, who are maintained in mammals, amphibians, birds, fish, insects and reptiles. These viruses rely on evolutionary unrelated helper viruses to provide envelopes and incorporate helper virus proteins for infectious particle formation. Deltaviruses (a genus in the family) can cause severe hepatitis and potentially other diseases in humans.
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 physical and biological properties in combination with their phylogenetic relationships.
These 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 freely available in the Journal of General Virology, and are supported by the Microbiology Society. These summaries are known as ICTV Virus Taxonomy Profiles and describe the structure, replication and taxonomy of each virus order and family.