Figure 1: Size of virus genome databases over time^{4,7,22,45,83,84,85,86,87,88,89}.

Genome sequences from isolates (blue and green) or from UViGs (yellow) are shown. For genomes from isolates, the total number of genomes (blue) and the number of 'reference' genomes (green) are shown. Data were downloaded using the queries “Viruses[Organism] AND srcdb_refseq[PROP] NOT wgs[PROP] NOT cellular organisms[ORGN] NOT AC_000001:AC_999999[PACC]” for reference genomes and “Viruses[Organism] NOT cellular organisms[ORGN] NOT wgs[PROP] NOT AC_000001:AC_999999[pacc] NOT gbdiv syn[prop] AND nuccore genome samespecies[Filter]” for total number of virus genomes, on the NCBI nucleotide database portal (https://www.ncbi.nlm.nih.gov/nuccore) in January 2018. Genomes from the influenza virus database (https://www.ncbi.nlm.nih.gov/genomes/FLU/Database/nph-select.cgi?go=genomeset) were also added to the total number of virus genomes. UViGs can be assembled from metagenomes, from proviruses identified in microbial genomes, or from single-virus genomes, and estimated total UViG numbers were obtained by compiling data from the literature and from the total number of sequences in the IMG/VR database in January 2017, January 2018 and July 2018 (https://img.jgi.doe.gov/vr/)¹¹. UpViG, uncultivated provirus.