en
Scientific article
Open access
English

Inefficient control of host gene expression by the 2009 pandemic H1N1 influenza A virus NS1 protein

Published inJournal of virology, vol. 84, no. 14, p. 6909-6922
Publication date2010
Abstract

In 2009, a novel swine-origin H1N1 influenza A virus emerged. Here, we characterize the multifunctional NS1 protein of this human pandemic virus in order to understand factors that may contribute to replication efficiency or pathogenicity. Although the 2009 H1N1 virus NS1 protein (2009/NS1) is an effective interferon antagonist, we found that this NS1 (unlike those of previous human-adapted influenza A viruses) is unable to block general host gene expression in human or swine cells. This property could be restored in 2009/NS1 by replacing R108, E125, and G189 with residues corresponding to human virus consensus. Mechanistically, these previously undescribed mutations acted by increasing binding of 2009/NS1 to the cellular pre-mRNA processing protein CPSF30. A recombinant 2009 H1N1 influenza A virus (A/California/04/09) expressing NS1 with these gain-of-function substitutions was more efficient than the wild type at antagonizing host innate immune responses in primary human epithelial cells. However, such mutations had no significant effect on virus replication in either human or swine tissue culture substrates. Surprisingly, in a mouse model of pathogenicity, the mutant virus appeared to cause less morbidity, and was cleared faster, than the wild type. The mutant virus also demonstrated reduced titers in the upper respiratory tracts of ferrets; however, contact and aerosol transmissibility of the virus was unaffected. Our data highlight a potential human adaptation of NS1 that seems absent in "classically derived" swine-origin influenza A viruses, including the 2009 H1N1 virus. We discuss the impact that a natural future gain of this NS1 function may have on the new pandemic virus in humans.

Keywords
  • Amino Acid Sequence
  • Animals
  • Cell Line
  • Disease Outbreaks
  • Ferrets
  • Gene Expression/physiology
  • Humans
  • Immunity, Innate
  • Influenza A Virus, H1N1 Subtype/genetics/immunology/pathogenicity
  • Influenza, Human/epidemiology/immunology/virology
  • Interferons/immunology
  • Mice
  • Molecular Sequence Data
  • Mutation
  • Orthomyxoviridae Infections/epidemiology/immunology/virology
  • Sequence Alignment
  • Swine
  • Viral Nonstructural Proteins/genetics/immunology
  • Virus Replication
Affiliation Not a UNIGE publication
Citation (ISO format)
HALE, Benjamin G et al. Inefficient control of host gene expression by the 2009 pandemic H1N1 influenza A virus NS1 protein. In: Journal of virology, 2010, vol. 84, n° 14, p. 6909–6922. doi: 10.1128/JVI.00081-10
Main files (1)
Article (Published version)
accessLevelPublic
Identifiers
ISSN of the journal0022-538X
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