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Influenza A Virus Studies in a Mouse Model of Infection
10:44

Influenza A Virus Studies in a Mouse Model of Infection

Published on: September 7, 2017

PB2 and hemagglutinin mutations are major determinants of host range and virulence in mouse-adapted influenza A virus

Jihui Ping1, Samar K Dankar, Nicole E Forbes

  • 1Department of Biochemistry, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, Canada K1H 8M5.

Journal of Virology
|August 13, 2010
PubMed

Insights

Influenza A virus adaptation to mice involves mutations in PB2 and hemagglutinin (HA) genes, significantly increasing virulence. These genetic changes enhance viral growth and polymerase activity, demonstrating multi-gene control over host range and pathogenicity.

Area of Science:

  • Virology
  • Molecular Biology
  • Pathogenesis

Background:

  • Influenza A virus adaptation to new hosts is a complex process involving genetic mutations.
  • Serial passage of human influenza A virus (H3N2) in mice generated a highly virulent variant (MA).

Purpose of the Study:

  • To identify the specific genetic determinants responsible for increased virulence and mouse adaptation of influenza A virus.
  • To elucidate the roles of individual viral genes in host range and pathogenicity.

Main Methods:

  • Generation of a mouse-adapted influenza A virus variant through serial lung passage.
  • Construction and characterization of recombinant viruses with specific gene segment mutations.
  • Assessment of viral virulence using 50% lethal dose (LD50) and clinical signs (weight loss, time to death).
  • In vitro minigenome transcription assays to evaluate polymerase activity.

Main Results:

  • Mutations in the PB2 (D701N) and hemagglutinin (HA) genes were identified as key determinants of increased mouse virulence.
  • Recombinant viruses with MA PB2 or HA genes showed significantly increased disease severity.
  • The PB2 D701N mutation conferred increased virulence comparable to the known mammalian adaptive mutation PB2 E627K.
  • Other gene segments (M1, NS1, NA, PB1) contributed to virulence attenuation when reverted to the wild-type sequence.

Conclusions:

  • Host range and virulence of influenza A virus are controlled by multiple viral genes, with PB2 and HA playing major roles.
  • Specific mutations in PB2 and HA are critical for efficient viral replication and pathogenicity in a new host.
  • Understanding these adaptive mutations provides insights into influenza virus evolution and pandemic potential.

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