Matthew Kaye, Merryn Roe, Erik A. Karlsson, Paul F. Horwood, Sokhoun Yann, San Sorn, Davun Holl, Aeron C. Hurt, Annika Suttie, Dhanasekaran Vijaykrishna, Songha Tok, Philippe Buchy, Ponnarath Keo, Srey Viseth Horm, Philippe Dussart, Ian G. Barr, Andrew R. Greenhill, Sothyra Tum, Yi Mo Deng, Unité de Virologie / Virology Unit [Phnom Penh], Institut Pasteur du Cambodge, Réseau International des Instituts Pasteur (RIIP)-Réseau International des Instituts Pasteur (RIIP), Federation University [Churchill, Australia], The Peter Doherty Institute for Infection and Immunity [Melbourne], The Royal Melbourne Hospital-University of Melbourne, Ministry of Agriculture, Forestry and Fisheries [Cambodia], GlaxoSmithKline Vaccines [Singapore], GlaxoSmithKline [Headquarters, London, UK] (GSK), Monash University [Melbourne], James Cook University (JCU), This publication is the result of work conducted under a cooperative agreement with the Office of the Assistant Secretary for Preparedness and Response in the U.S. Department of Health and Human Services (HHS), grant number IDSEP140020-01-00. Its contents and conclusions are solely the responsibility of the authors and do not represent the official views of HHS. The study was also funded, in part, by the US Agency for International Development (grant No. AID-442-G-14-00005) and partially funded through the UK Research and Innovation Global Challenges Research Fund to The Consortium of Animal Market Networks to Assess Risk of Emerging Infectious Diseases Through Enhanced Surveillance (CANARIES, and grant No. GCRFNGR3\1497). Annika Suttie is funded by an Australian Government Research Training Program Scholarship and a Faculty of Science and Technology Research Scholarship from Federation University. The Melbourne WHO Collaborating Centre for Reference and Research on Influenza is supported by the Australian Government Department of Health. GlaxoSmithKline Biologicals SA provided support in the form of salary for an author [PB], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific role of this author is articulated in the ‘author contributions’ section. The authors are solely responsible for final content and interpretation.
International audience; 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 2.3.2.1c 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 2.3.2.1c 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 2.3.2.1a, clade 2.3.2.1b 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 2.3.2.1c 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.