Avian H6 Influenza Viruses in Vietnamese Live Bird Markets during 2018–2021
Lizheng Guan,
Lavanya Babujee,
Robert Presler,
David Pattinson,
Hang Le Khanh Nguyen,
Vu Mai Phuong Hoang,
Mai Quynh Le,
Harm van Bakel,
Yoshihiro Kawaoka,
Gabriele Neumann
Affiliations
Lizheng Guan
Influenza Research Institute, Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin—Madison, Madison, WI 53711, USA
Lavanya Babujee
Influenza Research Institute, Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin—Madison, Madison, WI 53711, USA
Robert Presler
Influenza Research Institute, Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin—Madison, Madison, WI 53711, USA
David Pattinson
Influenza Research Institute, Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin—Madison, Madison, WI 53711, USA
Hang Le Khanh Nguyen
National Institute of Hygiene and Epidemiology, Hanoi 100000, Vietnam
Vu Mai Phuong Hoang
National Institute of Hygiene and Epidemiology, Hanoi 100000, Vietnam
Mai Quynh Le
National Institute of Hygiene and Epidemiology, Hanoi 100000, Vietnam
Harm van Bakel
Department of Genetics and Genomic Services, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
Yoshihiro Kawaoka
Influenza Research Institute, Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin—Madison, Madison, WI 53711, USA
Gabriele Neumann
Influenza Research Institute, Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin—Madison, Madison, WI 53711, USA
Avian influenza viruses of the H6 subtype are prevalent in wild ducks and likely play an important role in the ecology of influenza viruses through reassortment with other avian influenza viruses. Yet, only 152 Vietnamese H6 virus sequences were available in GISAID (Global Initiative on Sharing All Influenza Data) prior to this study with the most recent sequences being from 2018. Through surveillance in Vietnamese live bird markets from 2018 to 2021, we identified 287 samples containing one or several H6 viruses and other influenza A virus subtypes, demonstrating a high rate of co-infections among birds in Vietnamese live bird markets. For the 132 H6 samples with unique influenza virus sequences, we conducted phylogenetic and genetic analyses. Most of the H6 viruses were similar to each other and closely related to other H6 viruses; however, signs of reassortment with other avian influenza viruses were evident. At the genetic level, the Vietnamese H6 viruses characterized in our study encode a single basic amino acid at the HA cleavage site, consistent with low pathogenicity in poultry. The Vietnamese H6 viruses analyzed here possess an amino acid motif in HA that confers binding to both avian- and human-type receptors on host cells, consistent with their ability to infect mammals. The frequent detection of H6 viruses in Vietnamese live bird markets, the high rate of co-infections of birds with different influenza viruses, and the dual receptor-binding specificity of these viruses warrant their close monitoring for potential infection and spread among mammals.
