Rapid emergence of virus–host mutualism under stress

Viruses Defined by the Position of the Virosphere within the Replicator Space

“…Although all viruses indeed reproduce solely within host cells, the reverse is false: numerous obligate intracellular parasites are bacteria or unicellular eukaryotes rather than viruses. Furthermore, not all (and possibly not even the majority of) viruses are detrimental to their hosts, and some appear to be outright beneficial, thus qualifying as commensals or mutualists rather than parasites (75)(76)(77), although the strict dependence on the host cell and intracellular reproduction remain universal traits of these replicators (78,79).…”