title: Host Dependent Evolutionary Patterns and the Origin of 2009 H1N1 Pandemic Influenza.
abstract: The origin of H1N1pdm constitutes an unresolved mystery, as its most recently observed ancestors were isolated in pigs nearly a decade before it emerged in humans. One theory suggests imperfect surveillance of swine viruses caused the virus to be missed in swine herds. Other hypotheses point to the possibility of laboratory error or an avian intermediary. We show substitution bias classification identifies the host where a virus has been evolving. Comparing the evolution of H1N1pdm ancestors with other influenza viruses, we show the evolutionary history in unsampled years is similar to the evolution of other swine viruses, presenting evidence it emerged from unsampled herds.
authors.affiliation: Columbia Unoiversity;  Simons Center for Systems Biology, Institute for Advanced Study;  Center for Infection and Immunity and  Columbia University.
authors.forename: Alexander
authors.initials: A
authors.lastname: Solovyov
authors.forename: Benjamin
authors.initials: B
authors.lastname: Greenbaum
authors.forename: Gustavo
authors.initials: G
authors.lastname: Palacios
authors.forename: W Ian
authors.initials: WI
authors.lastname: Lipkin
authors.forename: Raul
authors.initials: R
authors.lastname: Rabadan