title: Short-Sighted Virus Evolution and a Germline Hypothesis for Chronic Viral Infections.
abstract: With extremely short generation times and high mutability, many viruses can rapidly evolve and adapt to changing environments. This ability is generally beneficial to viruses as it allows them to evade host immune responses, evolve new behaviours, and exploit ecological niches. However, natural selection typically generates adaptation in response to the immediate selection pressures that a virus experiences in its current host. Consequently, we argue that some viruses, particularly those characterised by long durations of infection and ongoing replication, may be susceptible to short-sighted evolution, whereby a virus' adaptation to its current host will be detrimental to its onward transmission within the host population. Here we outline the concept of short-sighted viral evolution and provide examples of how it may negatively impact viral transmission among hosts. We also propose that viruses that are vulnerable to short-sighted evolution may exhibit strategies that minimise its effects. We speculate on the various mechanisms by which this may be achieved, including viral life history strategies that result in low rates of within-host evolution, or the establishment of a 'germline' lineage of viruses that avoids short-sighted evolution. These concepts provide a new perspective on the way in which some viruses have been able to establish and maintain global pandemics.
authors.affiliation: Department of Zoology, University of Oxford, Oxford, OX1 3PS, UK. Electronic address: katrina.lythgoe@zoo.ox.ac.uk.
authors.forename: Katrina A
authors.initials: KA
authors.lastname: Lythgoe
authors.affiliation: School of Biology, University of St Andrews, St Andrews, KY16 9TH, UK.
authors.forename: Andy
authors.initials: A
authors.lastname: Gardner
authors.affiliation: Department of Zoology, University of Oxford, Oxford, OX1 3PS, UK.
authors.forename: Oliver G
authors.initials: OG
authors.lastname: Pybus
authors.affiliation: Division of Infection and Immunity, Institute of Immunity and Transplantation, University College London, London, WC1E 6BT, UK.
authors.forename: Joe
authors.initials: J
authors.lastname: Grove
mesh_terms: D002908:Chronic Disease; D019143:Evolution, Molecular; D054884:Host-Pathogen Interactions; D006801:Humans; D059645:Mutation Rate; D014777:Virus Diseases / Q000276:immunology / Q000635:transmission / Q000821:virology*; D014780:Viruses / Q000235:genetics* / Q000276:immunology
keywords: evolution; transmission; virus