A one year active surveillance program for influenza A viruses among avian species in a live-bird market (LBM) in Bangkok, Thailand was conducted in 2009. Out of 970 samples collected, influenza A virus subtypes H4N6 (n = 2) and H4N9 (n = 1) were isolated from healthy Muscovy ducks. All three viruses were characterized by whole genome sequencing with subsequent phylogenetic analysis and genetic comparison. Phylogenetic analysis of all eight viral genes showed that the viruses clustered in the Eurasian lineage of influenza A viruses. Genetic analysis showed that H4N6 and H4N9 viruses display low pathogenic avian influenza characteristics. The HA cleavage site and receptor binding sites were conserved and resembled to LPAI viruses. This study is the first to report isolation of H4N6 and H4N9 viruses from birds in LBM in Thailand and shows the genetic diversity of the viruses circulating in the LBM. In addition, co-infection of H4N6 and H4N9 in the same Muscovy duck was observed.
Bibliographical noteFunding Information:
This work has been funded in whole with federal funds from the National Institute of Allergy and Infectious Disease, National Institute of Health, Department of Health and Human Services, under Contract No. HHSN266200700007c. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIH. We also would like to thank the National Research Council of Thailand (NRCT, Thailand) and the National Research University of CHE and the Ratchadaphiseksomphot Endowment Fund (HR1155A) for grant support to AA. We would like to thank Chulalongkorn University for its financial support in the Emerging and Re-emerging Infectious Diseases in Animals, Research Unit. We would like to thank Ms. Petra Hirsch for reviewing the manuscript.