title: Reassortment between influenza B lineages and the emergence of a coadapted PB1-PB2-HA gene complex.
abstract: Influenza B viruses make a considerable contribution to morbidity attributed to seasonal influenza. Currently circulating influenza B isolates are known to belong to two antigenically distinct lineages referred to as B/Victoria and B/Yamagata. Frequent exchange of genomic segments of these two lineages has been noted in the past, but the observed patterns of reassortment have not been formalized in detail. We investigate interlineage reassortments by comparing phylogenetic trees across genomic segments. Our analyses indicate that of the eight segments of influenza B viruses only segments coding for polymerase basic 1 and 2 (PB1 and PB2) and hemagglutinin (HA) proteins have maintained separate Victoria and Yamagata lineages and that currently circulating strains possess PB1, PB2, and HA segments derived entirely from one or the other lineage; other segments have repeatedly reassorted between lineages thereby reducing genetic diversity. We argue that this difference between segments is due to selection against reassortant viruses with mixed-lineage PB1, PB2, and HA segments. Given sufficient time and continued recruitment to the reassortment-isolated PB1-PB2-HA gene complex, we expect influenza B viruses to eventually undergo sympatric speciation.
authors.affiliation: Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, United Kingdom g.dudas@sms.ed.ac.uk.
authors.forename: Gytis
authors.initials: G
authors.lastname: Dudas
authors.affiliation: Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA.
authors.forename: Trevor
authors.initials: T
authors.lastname: Bedford
authors.affiliation: Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, United Kingdom Institute of Biodiversity Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Samantha
authors.initials: S
authors.lastname: Lycett
authors.affiliation: Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, United Kingdom Fogarty International Center, National Institutes of Health, Bethesda, MD Centre for Immunology, Infection and Evolution at the University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Andrew
authors.initials: A
authors.lastname: Rambaut
mesh_terms: D019295:Computational Biology / Q000379:methods; D019143:Evolution, Molecular; D049810:Genetic Speciation; D016679:Genome, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics*; D006801:Humans; D009981:Influenza B virus / Q000145:classification* / Q000235:genetics*; D007251:Influenza, Human / Q000097:blood / Q000821:virology; D010802:Phylogeny; D012641:Selection, Genetic; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; C502893:PB2 protein, influenza virus; D014764:Viral Proteins; C077346:influenza virus polymerase basic protein 1
keywords: evolution; influenza; phylogenetics; reassortment; speciation