Genetic characterization of influenza A virus subtypes H1N3 and H1N9 isolated from free-grazing ducks in Thailand.

Influenza A virus (IAV) subtype H1 has been reported to infect birds, pigs and humans. In this study, we characterized IAVs subtype H1N3 and H1N9 isolated from free-grazing ducks in Thailand. Phylogenetic analysis showed that Thai IAV-H1 isolates cluster with avian Eurasian-lineage but not pandemic H1N1 viruses. Analysis of the viruses indicated low-pathogenic avian influenza (LPAI) characteristics. This study is the first report of avian H1N3 and H1N9 in Thailand. Although Thai IAV-H1 viruses do not pose a risk of a pandemic, routine surveillance and genetic monitoring of IAVs should be conducted.