The 7 th ICTV Report
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Virology Division News
The 7th ICTV Report C. M. Fauquet1 and M. A. Mayo2 1
ILTAB/Danforth Plant Science Center, University of Missouri St. Louis, St. Louis, Missouri, U.S.A. 2 Scottish Crop Research Institute, Dundee, U.K.
Introduction After an unexpected and much regretted delay, the seventh Report of the International Committee on Taxonomy of Viruses (ICTV) [8] has been published. The Report is the culmination of the efforts of the many virologists who have contributed to the diverse committees and Study Groups that constitute the ICTV. Some 476 virologists from many countries have been involved in various capacities during the interval following the publication of the previous Report [5]. The size, scope and content of the 7th Report are reflections of the enormous increase in virological knowledge during the last 5 years; the Report runs to 1162 pages that describe 3 Orders, 63 Families, 240 Genera. These compare with the taxonomy described in the previous Report that comprised 1 Order, 50 Families and 164 Genera. An important development since the 6th Report was published, has been a focus on the demarcation of species within the genera [6]. Previously, many viruses were listed but it was not clear which belonged to distinct species and which were strains or other sub-specific entities within a particular species. The current taxonomy [8] lists more than 3600 viruses among 1550 species. New features in the 7th Report New families and genera Fourteen new families are described in the 7th Report (Table 1). Some (e.g. Ascoviridae) contain new genera and others contain genera that were previously listed as “unassigned” or “floating” [5]. One family (Papovaviridae) described in the 6th Report has been divided into the new families Polyomaviridae and Papillomaviridae because of the profound differences between viruses in what were two genera in a single family. The new families contain genera of viruses that have genomes of 4 of the 6 major types. Also, the classification has been extended to include viroids. These have been classified into 7 genera that are distributed among 2 families. Other new genera have been classified into families that were already described in the 6th Report (Table 2). Some of these genera were formed by taking species out of their previous genus in recognition of its having become too diverse to be classified as one genus, some new genera were needed to classify novel virus species. Some of the genera listed in
Virology Division News
190 Table 1. New families in the 7th report Genome type
New Family
Genera
Host type
DsDNA
Rudiviridae Ascoviridae Asfarviridae Polyomaviridaea Papillomaviridaea
Rudivirus Ascovirus Asfivirus Polyomavirus Papillomavirus
Archaea Invertebrates Vertebrates Vertebrates Vertebrates
Reverse transcribing
Caulimoviridae
Caulimovirus PVCV-like viruses SCMoV-like viruses CVMV-like viruses Badnavirus RTBV-like viruses Pseudovirus Hemivirus Metavirus Errantivirus
Plants Plants Plants Plants Plants Plants Fungi/Plants Invertebrates/Fungi Fungi/Plants/Inver
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