title: A systematic review of reported reassortant viral lineages of influenza A.
abstract: BACKGROUND
  Most previous evolutionary studies of influenza A have focussed on genetic drift, or reassortment of specific gene segments, hosts or subtypes. We conducted a systematic literature review to identify reported claimed reassortant influenza A lineages with genomic data available in GenBank, to obtain 646 unique first-report isolates out of a possible 20,781 open-access genomes.
  
  
  RESULTS
  After adjusting for correlations, only: swine as host, China, Europe, Japan and years between 1997 and 2002; remained as significant risk factors for the reporting of reassortant viral lineages. For swine H1, more reassortants were observed in the North American H1 clade compared with the Eurasian avian-like H1N1 clade. Conversely, for avian H5 isolates, a higher number of reported reassortants were observed in the European H5N2/H3N2 clade compared with the H5N2 North American clade.
  
  
  CONCLUSIONS
  Despite unavoidable biases (publication, database choice and upload propensity) these results synthesize a large majority of the current literature on novel reported influenza A reassortants and are a potentially useful prerequisite to inform further algorithmic studies.
authors.affiliation: Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analyses and Modelling, School of Public Health, Imperial College London, London, UK. amy.pinsent07@imperial.ac.uk.
authors.forename: Amy
authors.initials: A
authors.lastname: Pinsent
authors.affiliation: Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analyses and Modelling, School of Public Health, Imperial College London, London, UK. c.fraser@imperial.ac.uk.
authors.forename: Christophe
authors.initials: C
authors.lastname: Fraser
authors.affiliation: Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analyses and Modelling, School of Public Health, Imperial College London, London, UK. n.ferguson@imperial.ac.uk.
authors.forename: Neil M
authors.initials: NM
authors.lastname: Ferguson
authors.affiliation: Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analyses and Modelling, School of Public Health, Imperial College London, London, UK. s.riley@imperial.ac.uk.
authors.forename: Steven
authors.initials: S
authors.lastname: Riley
mesh_terms: D000818:Animals; D040961:Genetic Drift; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics* / Q000302:isolation & purification; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics* / Q000302:isolation & purification; D053125:Influenza A Virus, H5N2 Subtype / Q000235:genetics*; D007251:Influenza, Human / Q000821:virology; D010802:Phylogeny; D016865:Reassortant Viruses / Q000235:genetics*