title: The meaning of persistent infections in nature.
abstract: Viruses that cause persistent infections maintain themselves more effectively in nature than those causing acute and limited infections. There is a tendency for persistent viruses to evolve towards a state of minimal pathogenicity in the host. Vertical transmission, with integration of viral into host genome, represents the state of perfect parasitism.
mesh_terms: D000818:Animals; D002908:Chronic Disease; D006801:Humans; D014777:Virus Diseases / Q000382:microbiology / Q000635:transmission; D014780:Viruses / Q000472:pathogenicity