title: Synergistic adaptive mutations in the hemagglutinin and polymerase acidic protein lead to increased virulence of pandemic 2009 H1N1 influenza A virus in mice.
abstract: Influenza impressively reflects the paradigm of a viral disease in which continued evolution of the virus is of paramount importance for annual epidemics and occasional pandemics in humans. Because of the continuous threat of novel influenza outbreaks, it is essential to gather further knowledge about viral pathogenicity determinants. Here, we explored the adaptive potential of the influenza A virus subtype H1N1 variant isolate A/Hamburg/04/09 (HH/04) by sequential passaging in mice lungs. Three passages in mice lungs were sufficient to dramatically enhance pathogenicity of HH/04. Sequence analysis identified 4 nonsynonymous mutations in the third passage virus. Using reverse genetics, 3 synergistically acting mutations were defined as pathogenicity determinants, comprising 2 mutations in the hemagglutinin (HA[D222G] and HA[K163E]), whereby the HA(D222G) mutation was shown to determine receptor binding specificity and the polymerase acidic (PA) protein F35L mutation increasing polymerase activity. In conclusion, synergistic action of all 3 mutations results in a mice lethal pandemic H1N1 virus.
authors.affiliation: Institute of Molecular Virology, ZMBE, Muenster, Germany.
authors.forename: Roman
authors.initials: R
authors.lastname: Seyer
authors.forename: Eike R
authors.initials: ER
authors.lastname: Hrincius
authors.forename: Dorothea
authors.initials: D
authors.lastname: Ritzel
authors.forename: Marion
authors.initials: M
authors.lastname: Abt
authors.forename: Alexander
authors.initials: A
authors.lastname: Mellmann
authors.forename: Henju
authors.initials: H
authors.lastname: Marjuki
authors.forename: Joachim
authors.initials: J
authors.lastname: Kühn
authors.forename: Thorsten
authors.initials: T
authors.lastname: Wolff
authors.forename: Stephan
authors.initials: S
authors.lastname: Ludwig
authors.forename: Christina
authors.initials: C
authors.lastname: Ehrhardt
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D004252:DNA Mutational Analysis; D006389:Hemagglutinins, Viral / Q000235:genetics*; D053118:Influenza A Virus, H1N1 Subtype / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D023421:Models, Animal; D009439:Neuraminidase / Q000235:genetics; D009976:Orthomyxoviridae Infections / Q000235:genetics* / Q000503:physiopathology; D017354:Point Mutation; D021122:Protein Subunits / Q000235:genetics*; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics*; D012692:Serial Passage; D014764:Viral Proteins / Q000235:genetics*; D037521:Virulence Factors / Q000235:genetics; D015431:Weight Loss
chemical_list: D006389:Hemagglutinins, Viral; C061290:PA protein, influenza viruses; D021122:Protein Subunits; D014764:Viral Proteins; D037521:Virulence Factors; D012324:RNA-Dependent RNA Polymerase; D009439:Neuraminidase