| The number and diversity of viral sequences that are identified in metagenomic data far exceeds that of experimentally characterized virus isolates. In a recent workshop, a panel of experts discussed the proposal that, with appropriate quality control, viruses that are known only from metagenomic data can, and should be, incorporated into the official classification scheme of the International Committee on Taxonomy of Viruses (ICTV). Although a taxonomy that is based on metagenomic sequence data alone represents a substantial departure from the traditional reliance on phenotypic properties, the development of a robust framework for sequence-based virus taxonomy is indispensable for the comprehensive characterization of the global virome. In this Consensus Statement article, we consider the rationale for why metagenomic sequence data should, and how it can, be incorporated into the ICTV taxonomy, and present proposals that have been endorsed by the Executive Committee of the ICTV. NATURE REVIEWS | MICROBIOLOGY VOLUME 15 | MARCH 2017 | 161 CONSENSUS STATEMENT © 2 0 1 7 M a c m i l l a n P u b l i s h e r s L i m i t e d , p a r t o f S p r i n g e r N a t u r e . A l l r i g h t s r e s e r v e d .

This review provides an update of the genetic content, phylogeny and evolution of the family Adenoviridae. An appraisal of the condition of adenovirus genomics highlights the need to ensure that public sequence information is interpreted accurately. To this end, all complete genome sequences available have been reannotated. Adenoviruses fall into four recognized genera, plus possibly a fifth, which have apparently evolved with their vertebrate hosts, but have also engaged in a number of interspecies transmission events. Genes inherited by all modern adenoviruses from their common ancestor are located centrally in the genome and are involved in replication and packaging of viral DNA and formation and structure of the virion. Additional niche-specific genes have accumulated in each lineage, mostly near the genome termini. Capture and duplication of genes in the setting of a 'leader-exon structure', which results from widespread use of splicing, appear to have been central to adenovirus evolution. The antiquity of the pre-vertebrate lineages that ultimately gave rise to the Adenoviridae is illustrated by morphological similarities between adenoviruses and bacteriophages, and by use of a protein-primed DNA replication strategy by adenoviruses, certain bacteria and bacteriophages, and linear plasmids of fungi and plants. INTRODUCTIONThe purpose of this review is to provide a comprehensive update of the genetic content, phylogeny and evolution of the family Adenoviridae, whose members infect hosts throughout the vertebrates (Russell & Benkó´, 1999). This area has frequently taken a back seat to studies of the interactions of selected human adenovirus proteins with cellular processes and, more recently, to the use of adenoviruses as vectors. Our aim is to redress this imbalance by bringing together published information and by offering fresh insights into the genomics of the family as a whole. It is not our purpose to deal in broad scope with other areas, such as the expression, functions and interactions of adenovirus gene products and the ways in which host defences are manipulated during the infectious cycle. These have been reviewed recently by Russell (2000) and Shenk (2001) for human adenoviruses. Phylogeny, classification and genetic organizationMembers of the family Adenoviridae are non-enveloped, icosahedral viruses that replicate in the nucleus. Their linear, double-stranded DNA molecules are 26-45 kbp in size and rank as medium-sized among the DNA viruses. The genomes are characterized by an inverted terminal repeat (ITR) ranging in size from 36 to over 200 bp, and the 59 ends are linked to a terminal protein (TP). Phylogenetic relationships among a large number of adenoviruses infecting vertebrates from fish to humans are shown in Fig. 1. The major clades (groups of viruses sharing a common ancestor) correspond to the four accepted genera plus a fifth genus that is likely to be added in due course (Benkó´et al., 2002;. Two genera (Mastadenovirus and Aviadenovirus) originate from mammals or birds, respective...