An Ecological Framework of the Human Virome Provides Classification of Current Knowledge and Identifies Areas of Forthcoming Discovery

Parker, Michael T.

The canonical classification of viruses is as parasites. In general, parasitic viruses are transmitted horizontally from host to host, and this process is necessary for the virus' survival. Their obligate life cycles necessitate manipulation of cellular processes and have been classically linked to disease manifestation. While the role of viruses in human disease was not appreciated until the 19th century [28] , throughout human history, the diseases caused by particularly pathogenic viruses have been some of the most feared and deadly. Currently, there are 129 known human viral pathogens [29] and at least 219 viruses that can infect humans [30] , with more being discovered every year [31, 32] . The apparent bias toward pathogenic species is undeniably because phenotype (read: pathogenesis) has traditionally been a major factor in the discovery of new viruses.