title: Adaptive mutations in NEP compensate for defective H5N1 RNA replication in cultured human cells.
abstract: Infection of mammals by avian influenza viruses requires adaptive mutations to achieve high-level replication in the new host. However, the basic mechanism underlying this adaptation process is still unknown. Here we show that avian polymerases, lacking the human signature PB2-E627K, are incapable of generating usable complementary RNA templates in cultured human cells and therefore require adaptation. Characterization of the highly pathogenic human H5N1 isolate A/Thailand/1(KAN-1)/2004 that retained the avian PB2-E627 reveals that the defect in RNA replication is only partially compensated by mutations in the polymerase. Instead, mutations in the nuclear export protein are required for efficient polymerase activity. We demonstrate that adaptive mutations in nuclear export proteins of several human isolates enhance the polymerase activity of avian polymerases in human cultured cells. In conclusion, when crossing the species barrier, avian influenza viruses acquire adaptive mutations in nuclear export protein to escape restricted viral genome replication in mammalian cells.
authors.affiliation: Department of Virology, Institute for Medical Microbiology and Hygiene, University of Freiburg, 79104, Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Mänz
authors.forename: Linda
authors.initials: L
authors.lastname: Brunotte
authors.forename: Peter
authors.initials: P
authors.lastname: Reuther
authors.forename: Martin
authors.initials: M
authors.lastname: Schwemmle
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D002460:Cell Line; D005260:Female; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology; D007251:Influenza, Human / Q000821:virology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D012324:RNA-Dependent RNA Polymerase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014774:Virulence; D014779:Virus Replication
chemical_list: C556232:NS2 protein, influenza virus A; C057027:PB2 protein, Influenzavirus A; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase