(b) Box and whisker plots showing range … Taxonomic Diversity The taxonomic diversity of sequenced marine phages is quite low as compared to the diversity of the sequenced selleck inhibitor phages from all habitats (Figure 6). Of the 27 marine phages sequenced, all are double-stranded DNA phages, with no RNA stage; 96% are of the viral order Caudovirales (Pseudoalteromonas phage PM2 has an unclassified order and belongs to the Corticoviridae family), as opposed to 76% of all sequenced phages (123 phages with no order span 13 different Classes). Figure 6 Overview of phage taxonomic data. (a)The taxonomic distribution of all sequenced phages versus all sequenced marine phages and (b) the hosts of all sequenced marine phages. All information describing marine phages and their hosts is accessible via GCDML ..

. Among all sequenced phages, there is general bias towards double-stranded DNA (dsDNA) viruses lacking an RNA stage (possibly influenced by, e.g., cloning biases in sequencing efforts, chloroform extractions that disrupt lipid-membranes of, i.e., dsRNA viruses, the difficulty in culturing archaeal hosts, etc.), despite the fact that, from an epidemiological perspective, over 75% of all viral diseases are the result of RNA viruses [27], which are yet to be represented by any sequenced marine phage isolates. The odd dsRNA phages have segmented genomes, whereby multiple ‘chromosomes’ exist in each virion and are often re-assorted during co-infection of the same host [28], where phages can exist in a ‘carrier state’, reproducing without killing their host [29].

This feature, combined with the intrinsic low fidelity of RNA replication, allows for RNA viruses to rapidly adapt to new environments, offering insights into modeling of viral population genetics and evolutionary theory that we can not yet consider in the marine realm [27]. ssDNA phages are also one of the major ‘odd’ phages groups not yet represented in the marine phage genome collection (Panel a Brefeldin_A of Figure 6), and are also under selective pressure quite unique from their dsDNA counterparts [30]. Distribution of hosts The distribution of their hosts is also biased (Figures 4 and and5).5). Two thirds of the sequenced marine phages infect Proteobacteria. Furthermore, most hosts are restricted to three major sets; 30% infect Vibrio spp., 33% infect Cyanobacteria (either Chroococcales or Prochlorales), and another 30% infect Alphaproteobacteria (all but one infect Rhodobacterales) (Panel b of Figure 6). All sequenced marine phages infect only two of the twenty-four Bacteria phyla (Proteobacteria and Cyanobacteria) and no Archaea (Panel b of Figure 6).