Changes in adaptation of H5N2 highly pathogenic avian influenza H5 clade 2.3.4.4 viruses in chickens and mallards

Virology. 2016 Dec:499:52-64. doi: 10.1016/j.virol.2016.08.036. Epub 2016 Sep 12.

Abstract

H5N2 highly pathogenic avian influenza (HPAI) viruses caused a severe poultry outbreak in the United States (U.S.) during 2015. In order to examine changes in adaptation of this viral lineage, the infectivity, pathogenicity and transmission of poultry H5N2 viruses were investigated in chickens and mallards in comparison to the wild duck 2014 U.S. index H5N2 virus. The four poultry isolates examined had a lower mean bird infectious dose than the index virus but still transmitted poorly to direct contacts. In mallards, two of the H5N2 poultry isolates had similar high infectivity and transmissibility as the index H5N2 virus, the H5N8 U.S. index virus, and a 2005 H5N1 clade 2.2 virus. Mortality occurred with the H5N1 virus and, interestingly, with one of two poultry H5N2 isolates. Increased virus adaptation to chickens was observed with the poultry H5N2 viruses; however these viruses retained high adaptation to mallards but pathogenicity was differently affected.

Keywords: Adaptation; Chickens; H5N1; H5N2; H5N8; Highly pathogenic avian influenza virus; Infectivity; Mallards; Pathogenicity; Transmission.

MeSH terms

  • Adaptation, Biological*
  • Animals
  • Chickens*
  • Ducks*
  • Genetic Variation
  • Influenza A Virus, H5N2 Subtype / classification*
  • Influenza A Virus, H5N2 Subtype / physiology*
  • Influenza in Birds / mortality
  • Influenza in Birds / transmission
  • Influenza in Birds / virology*
  • RNA, Viral
  • Sequence Analysis, DNA
  • Viral Load
  • Virus Shedding

Substances

  • RNA, Viral