Transmission experiments support clade-level differences in the transmission and pathogenicity of Cambodian influenza A/H5N1 viruses

Horwood, Paul F., Fabrizio, Thomas, Horm, Srey Viseth, Metlin, Artem, Ros, Sopheaktra, Tok, Songha, Trushar, Jeevan, Seiler, Patrick, Y, Phalla, Rith, Sareth, Suttie, Annika, Buchy, Philippe, Karlsson, Erik A., Webby, Richard, and Dussart, Philippe (2020) Transmission experiments support clade-level differences in the transmission and pathogenicity of Cambodian influenza A/H5N1 viruses. Emerging Microbes & Infections, 9 (1). pp. 1702-1711.

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Influenza A/H5N1 has circulated in Asia since 2003 and is now enzootic in many countries in that region. In Cambodia, the virus has circulated since 2004 and has intermittently infected humans. During this period, we have noted differences in the rate of infections in humans, potentially associated with the circulation of different viral clades. In particular, a reassortant clade 1.1.2 virus emerged in early 2013 and was associated with a dramatic increase in infections of humans (34 cases) until it was replaced by a clade virus in early 2014. In contrast, only one infection of a human has been reported in the 6 years since the clade virus became the dominant circulating virus. We selected three viruses to represent the main viral clades that have circulated in Cambodia (clade 1.1.2, clade 1.1.2 reassortant, and clade, and we conducted experiments to assess the virulence and transmissibility of these viruses in avian (chicken, duck) and mammalian (ferret) models. Our results suggest that the clade virus is more “avian-like,” with high virulence in both ducks and chickens, but there is no evidence of aerosol transmission of the virus from ducks to ferrets. In contrast, the two clade 1 viruses were less virulent in experimentally infected and contact ducks. However, evidence of chicken-to-ferret aerosol transmission was observed for both clade 1 viruses. The transmission experiments provide insights into clade-level differences that might explain the variation in A/H5N1 infections of humans observed in Cambodia and other settings.

Item ID: 63875
Item Type: Article (Research - C1)
ISSN: 2222-1751
Keywords: Influenza, H5N1, avian, transmission, poultry, ducks, ferrets, Cambodia
Copyright Information: © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group, on behalf of Shanghai Shangyixun Cultural Communication Co., Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Funders: US Agency for International Development (USAID), National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Department of Health and Human Services
Projects and Grants: USAID grant number AID-442-G-14-00005, CEIRS contract no. HHSN272201400006C.
Date Deposited: 28 Jul 2020 04:59
FoR Codes: 30 AGRICULTURAL, VETERINARY AND FOOD SCIENCES > 3009 Veterinary sciences > 300914 Veterinary virology @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970107 Expanding Knowledge in the Agricultural and Veterinary Sciences @ 100%
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