PB2 and HA mutations increase the virulence of highly pathogenic H5N5 clade 2.3.4.4 avian influenza virus in mice

Arch Virol. 2018 Feb;163(2):401-410. doi: 10.1007/s00705-017-3631-7. Epub 2017 Oct 31.

Abstract

H5 clade 2.3.4.4 influenza A viruses pose a potential threat to public health and are a cause of public concern. Here, we generated mouse-adapted viruses of a waterfowl-origin H5N5 virus (H5 clade 2.3.4.4) to identify adaptive changes that confer increased virulence in mammals. After two passages, we obtained a mouse-adapted H5N5 virus that contained single amino acid substitutions in the PB2 (E627K) and hemagglutinin (HA) (F430L) proteins. We then analyzed the impact of these individual amino acid substitutions on viral pathogenicity to mammals. The 50% mouse lethal dose (MLD50) of the H5N5 virus containing the PB2-E627K substitution or the HA-F430L substitution was reduced 1000-fold or 3.16-fold, respectively. Furthermore, we found that PB2-E627K enhanced viral replication kinetics in vitro and in vivo. These results suggest that the PB2-E627K and HA-F430L substitutions are important for adaptation of H5N5 AIVs to mammals. These findings emphasize the importance of continued surveillance of poultry for H5N5 AIVs with these amino acid substitutions.

MeSH terms

  • Amino Acid Substitution
  • Animals
  • Anseriformes / virology
  • Female
  • Hemagglutinin Glycoproteins, Influenza Virus / genetics*
  • Hemagglutinin Glycoproteins, Influenza Virus / metabolism
  • Influenza A virus / enzymology
  • Influenza A virus / genetics*
  • Influenza A virus / metabolism
  • Influenza A virus / pathogenicity*
  • Influenza in Birds / virology*
  • Mice
  • Mice, Inbred BALB C
  • Mutation, Missense
  • RNA-Dependent RNA Polymerase / genetics*
  • RNA-Dependent RNA Polymerase / metabolism
  • Viral Proteins / genetics*
  • Viral Proteins / metabolism
  • Virulence

Substances

  • Hemagglutinin Glycoproteins, Influenza Virus
  • PB2 protein, Influenzavirus A
  • Viral Proteins
  • RNA-Dependent RNA Polymerase