title: Possible increased pathogenicity of pandemic (H1N1) 2009 influenza virus upon reassortment.
abstract: Since emergence of the pandemic (H1N1) 2009 virus in April 2009, three influenza A viruses-seasonal (H3N2), seasonal (H1N1), and pandemic (H1N1) 2009-have circulated in humans. Genetic reassortment between these viruses could result in enhanced pathogenicity. We compared 4 reassortant viruses with favorable in vitro replication properties with the wild-type pandemic (H1N1) 2009 virus with respect to replication kinetics in vitro and pathogenicity and transmission in ferrets. Pandemic (H1N1) 2009 viruses containing basic polymerase 2 alone or in combination with acidic polymerase of seasonal (H1N1) virus were attenuated in ferrets. In contrast, pandemic (H1N1) 2009 with neuraminidase of seasonal (H3N2) virus resulted in increased virus replication and more severe pulmonary lesions. The data show that pandemic (H1N1) 2009 virus has the potential to reassort with seasonal influenza viruses, which may result in increased pathogenicity while it maintains the capacity of transmission through aerosols or respiratory droplets.
authors.affiliation: National Influenza Centre and Erasmus Medical Center Department of Virology, Rotterdam, the Netherlands.
authors.forename: Eefje J A
authors.initials: EJ
authors.lastname: Schrauwen
authors.forename: Sander
authors.initials: S
authors.lastname: Herfst
authors.forename: Salin
authors.initials: S
authors.lastname: Chutinimitkul
authors.forename: Theo M
authors.initials: TM
authors.lastname: Bestebroer
authors.forename: Guus F
authors.initials: GF
authors.lastname: Rimmelzwaan
authors.forename: Albert D M E
authors.initials: AD
authors.lastname: Osterhaus
authors.forename: Thijs
authors.initials: T
authors.lastname: Kuiken
authors.forename: Ron A M
authors.initials: RA
authors.lastname: Fouchier
mesh_terms: D000818:Animals; D002460:Cell Line; D005289:Ferrets; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics* / Q000472:pathogenicity*; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics* / Q000472:pathogenicity; D009976:Orthomyxoviridae Infections / Q000821:virology; D058873:Pandemics; D016865:Reassortant Viruses / Q000235:genetics* / Q000472:pathogenicity*; D012137:Respiratory System / Q000473:pathology / Q000821:virology; D012621:Seasons; D012720:Severity of Illness Index