Virus identification and genome sequencing
All experiments were conducted under biosafety level (BSL)-2 conditions. The swab tubes were swirled, and the supernatants were collected after centrifugation. RNAs were extracted by referring to the manual of MagMAXTM Pathogen RNA/DNA Kit (Applied Biosystems, USA). The extraction process was completed on the Magmax-96 Express instrument (Applied Biosystems). After extraction, positive samples were screened using a real-time reverse transcription PCR system with primers specific for the matrix gene primer and probe set (WHO, 2009) on a 7500 real-time PCR instrument (Applied Biosystems), and then positive samples were transcribed into cDNA using the Uni12 primer (5’-AGC AAA AGC AGG-3’) and PrimScript™ II 1st Strand cDNA Synthesis Kit (Takara, Japan). The subtypes were determined using specific primers for HA and NA (Huang et al., 2013; Kim et al., 2019) and the eight segments of these H10-H12 subtypes were amplified using the universal primers (Hoffmann et al., 2001). The PCR reaction contained 1 μL of cDNA, 1 μL of forward and reverse primers, 12.5 μL of Taq HS Perfect Mix (Takara, Japan) and 10.5 μL Rnase-free water, with a final volume of 25 μL. All sequences were confirmed using a BigDye termination kit (Applied Biosystems, Foster City, CA, USA) on an ABI 3730 sequence analyzer.