From deep sequencing to viral tagging: recent advances in viral metagenomics.

Culture-independent high-throughput sequencing has provided unprecedented insights into microbial ecology, particularly for Earth's most ubiquitous and diverse inhabitants - the viruses. A plethora of methods now exist for amplifying the vanishingly small amounts of nucleic acids in natural viral communities in order to sequence them, and sequencing depth is now so great that viral genomes can be detected and assembled even amid large concentrations of non-viral DNA. Complementing these advances in amplification and sequencing is the ability to physically link fluorescently labeled viruses to their host cells via high-throughput flow sorting. Sequencing of such isolated virus-host pairs facilitates cultivation-independent exploration of the natural host range of viruses. Within the next decade, as these technologies become widespread, we can expect to see a systematic expansion of our knowledge of viruses and their hosts.