title: Matters of Size: Genetic Bottlenecks in Virus Infection and Their Potential Impact on Evolution.
abstract: For virus infections of multicellular hosts, narrow genetic bottlenecks during transmission and within-host spread appear to be widespread. These bottlenecks will affect the maintenance of genetic variation in a virus population and the prevalence of mixed-strain infections, thereby ultimately determining the strength with which different random forces act during evolution. Here we consider different approaches for estimating bottleneck sizes and weigh their merits. We then review quantitative estimates of bottleneck size during cellular infection, within-host spread, horizontal transmission, and finally vertical transmission. In most cases we find that bottlenecks do regularly occur, although in many cases they appear to be virion-concentration dependent. Finally, we consider the evolutionary implications of genetic bottlenecks during virus infection. Although on average strong bottlenecks will lead to declines in fitness, we consider a number of scenarios in which bottlenecks could also be advantageous for viruses.
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politècnica de València, 46022 València, Spain; email: santiago.elena@csic.es.|Institute of Theoretical Physics, University of Cologne, 50937 Cologne, Germany; email: mzwart@uni-koeln.de.
authors.forename: Mark P
authors.initials: MP
authors.lastname: Zwart
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politècnica de València, 46022 València, Spain; email: santiago.elena@csic.es.|The Santa Fe Institute, Santa Fe, New Mexico 87501.
authors.forename: Santiago F
authors.initials: SF
authors.lastname: Elena
mesh_terms: D000818:Animals; D005075:Biological Evolution; D059646:Genome Size; D006801:Humans; D014777:Virus Diseases / Q000821:virology*; D018406:Virus Physiological Phenomena; D014780:Viruses / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification
keywords: genetic random drift; genetic variability; horizontal transmission; independent action hypothesis; vertical transmission; virus evolution