Diversity of A(H5N1) clade avian influenza viruses with evidence of reassortment in Cambodia, 2014-2016

Annika Suttie, Songha Tok, Sokhoun Yann, Ponnarath Keo, Srey Viseth Horm, Merryn Roe, Matthew Kaye, San Sorn, Davun Holl, Sothyra Tum, Philippe Buchy, Ian Barr, Aeron Hurt, Andrew R. Greenhill, Erik A. Karlsson, Dhanasekaran Vijaykrishna, Yi Mo Deng, Philippe Dussart, Paul F. Horwood

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In Cambodia, highly pathogenic avian influenza A(H5N1) subtype viruses circulate endemically causing poultry outbreaks and zoonotic human cases. To investigate the genomic diversity and development of endemicity of the predominantly circulating clade A (H5N1) viruses, we characterised 68 AIVs detected in poultry, the environment and from a single human A(H5N1) case from January 2014 to December 2016. Full genomes were generated for 42 A(H5N1) viruses. Phylogenetic analysis shows that five clade genotypes, designated KH1 to KH5, were circulating in Cambodia during this period. The genotypes arose through multiple reassortment events with the neuraminidase (NA) and internal genes belonging to H5N1 clade, clade or A(H9N2) lineages. Phylogenies suggest that the Cambodian AIVs were derived from viruses circulating between Cambodian and Vietnamese poultry. Molecular analyses show that these viruses contained the hemagglutinin (HA) gene substitutions D94N, S133A, S155N, T156A, T188I and K189R known to increase binding to the human-type α2,6-linked sialic acid receptors. Two A (H5N1) viruses displayed the M2 gene S31N or A30T substitutions indicative of adamantane resistance, however, susceptibility testing towards neuraminidase inhibitors (oseltamivir, zanamivir, lananmivir and peramivir) of a subset of thirty clade viruses showed susceptibility to all four drugs. This study shows that A(H5N1) viruses continue to reassort with other A(H5N1) and A(H9N2) viruses that are endemic in the region, highlighting the risk of introduction and emergence of novel A(H5N1) genotypes in Cambodia.

Original languageEnglish
Article numbere0226108
Number of pages25
JournalPLoS ONE
Issue number12
Publication statusPublished - 9 Dec 2019


  • poultry
  • phylogenetic analysis
  • viral pathogens
  • microbial mutation
  • Cambodia
  • infectious disease surveillance
  • population genetics
  • viral genomics

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