All experiments were conducted under biosafety level (BSL)-2 conditions. The swab-containing tubes were swirled, and the supernatants were collected after centrifugation. AIV RNAs were extracted using the MagMAX™ Pathogen RNA/DNA Kit (Applied Biosystems, Foster City, CA, USA) with the Magmax-96 Express instrument (Applied Biosystems). After extraction, the samples were screened for the presence of AIVs by real-time reverse transcription PCR (qRT-PCR) with primers and probes (WHO, 2009) specific to the matrix gene using a 7500 real-time PCR instrument (Applied Biosystems). The positive samples were transcribed into cDNA using the Uni12 primer (5ʹ-AGC AAA AGC AGG-3ʹ) and PrimeScript™ II 1st Strand cDNA synthesis kit (Takara, Japan). AIV subtypes were determined using primers specific to HA and NA genes [19 (link),22 (link)], and the eight segments of the H10–H12 AIV isolates were amplified using universal primers [23 (link)]. The PCR reactions consisted of 1 μL of cDNA, 1 μL each of forward and reverse primers, 12.5 μL of Taq HS Perfect Mix (Takara, Shiga, Japan) and 10.5 μL of RNAse-free water, with a final volume of 25 μL. All PCR products were sequenced by Sangon Biotech Co, Ltd (Shanghai, China) using a BigDye termination kit on an ABI 3730 sequence analyzer (Applied Biosystems, Foster City, CA, USA).
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