Taxonomy and Classification

The first iridovirus (IV) to be described was isolated from the larvae of the crane fly Tipula paludosa, discovered by Claude Rivers in 1954. The systemic infection conferred a blue coloration to the larvae and the term iridescent virus was coined. Since then similar viruses have been isolated from different parts of the world and different invertebrate species. Iridoviruses have been isolated from invertebrates indigenous to all the major continents. The nomenclature of these viruses can be confusing as they were sometimes referred to by their historical designation, based on host of isolation, or by their type number. In the interim typing scheme viruses were assigned type numbers depending on the chronological order of their isolation. Since Tipula iridescent virus (TIV) was the first discovered it has been designated iridovirus type 1 (IV1), whereas CIV, being the sixth to be reported, was iridovirus type 6 (IV6). The problems associated with both these nomenclature systems have led to the suggestion that they should be replaced with geographical descriptors. TIV would thus become Plowden IV, Plowden being the nearest major town to the site of isolation. This system is analogous to that used for many virus families,

Table 1 invertebrate iridescent viruses3

Type/alternative name

Host of isolation

IV1/TIV

Típula paludosa

IV2/SIV

Sericesthis pruinosa

IV3b

Aedes taeniorhynchus

IV6/CIV

Chilo suppressalis

IV9/WIV

Wiseana cervinata

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