title: A release-competent influenza A virus mutant lacking the coding capacity for the neuraminidase active site.
abstract: Both influenza A virus surface glycoproteins, the haemagglutinin (HA) and neuraminidase (NA), interact with neuraminic acid-containing receptors. The influenza virus A/Charlottesville/31/95 (H1N1) has shown a substantially reduced sensitivity to NA inhibitor compared with the A/WSN/33 (H1N1) isolate by plaque-reduction assays in Madin-Darby canine kidney (MDCK) cells. However, there was no difference in drug sensitivity in an NA inhibition assay. The replacement of the HA gene of A/WSN/33 with the HA gene of A/Charlottesville/31/95 led to a drastic reduction in sensitivity of A/WSN/33 to NA inhibitor in MDCK cells. Passage of A/Charlottesville/31/95 in cell culture in the presence of an NA inhibitor resulted in the emergence of mutant viruses (delNA) whose genomes lacked the coding capacity for the NA active site. The delNA mutants were plaque-to-plaque purified and further characterized. The delNA-31 mutant produced appreciable yields ( approximately 10(6) p.f.u./ml) in MDCK cell culture supernatants in the absence of viral or bacterial NA activity. Sequence analysis of the delNA mutant genome revealed no compensatory substitutions in the HA or other genes compared with the wild-type. Our data indicate that sialylation of the oligosaccharide chains in the vicinity of the HA receptor-binding site of A/Charlottesville/31/95 virus reduces the HA binding efficiency and thus serves as a compensatory mechanism for the loss of NA activity. Hyperglycosylation of HA is common in influenza A viruses circulating in humans and has the potential to reduce virus sensitivity to NA inhibitors.
authors.affiliation: DI Ivanovsky Institute of Virology, 16 Gamaleya Str., Moscow 123098, Russia2.|Department of Internal Medicine, University of Virginia, 1300 Jefferson Park Avenue, Jordan Hall Room 2231, PO Box 800473, Charlottesville, VA 22908, USA1.
authors.forename: Larisa V
authors.initials: LV
authors.lastname: Gubareva
authors.affiliation: DI Ivanovsky Institute of Virology, 16 Gamaleya Str., Moscow 123098, Russia2.|Department of Internal Medicine, University of Virginia, 1300 Jefferson Park Avenue, Jordan Hall Room 2231, PO Box 800473, Charlottesville, VA 22908, USA1.
authors.forename: Marina S
authors.initials: MS
authors.lastname: Nedyalkova
authors.affiliation: Department of Internal Medicine, University of Virginia, 1300 Jefferson Park Avenue, Jordan Hall Room 2231, PO Box 800473, Charlottesville, VA 22908, USA1.
authors.forename: Dmitri V
authors.initials: DV
authors.lastname: Novikov
authors.affiliation: Department of Virology and Molecular Biology, St Jude Children's Research Hospital, 332 North Lauderdale Str., Memphis, TN 38108, USA3.
authors.forename: K Gopal
authors.initials: KG
authors.lastname: Murti
authors.affiliation: Department of Virology and Molecular Biology, St Jude Children's Research Hospital, 332 North Lauderdale Str., Memphis, TN 38108, USA3.
authors.forename: Erich
authors.initials: E
authors.lastname: Hoffmann
authors.affiliation: Department of Internal Medicine, University of Virginia, 1300 Jefferson Park Avenue, Jordan Hall Room 2231, PO Box 800473, Charlottesville, VA 22908, USA1.
authors.forename: Frederick G
authors.initials: FG
authors.lastname: Hayden
mesh_terms: D000146:Acids, Carbocyclic; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D003517:Cyclopentanes / Q000494:pharmacology*; D004279:DNA, Viral; D004285:Dogs; D006146:Guanidines; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009980:Influenza A virus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D016296:Mutagenesis; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D009439:Neuraminidase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011995:Recombination, Genetic; D014779:Virus Replication
chemical_list: D000146:Acids, Carbocyclic; D003517:Cyclopentanes; D004279:DNA, Viral; D006146:Guanidines; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D009439:Neuraminidase; D019158:N-Acetylneuraminic Acid; C414210:peramivir