Fig. 5

Infection trial to test the sampling methods and storage buffers. Twenty SPF chickens received intranasal inoculation of AIV-H9N2. Three-days post inoculation, oropharyngeal swabs were obtained from each chicken with gentle, intermediate and thorough swabbing into PBS for immediate DNA extraction. Thereafter, every two hours, the thorough swabbing was performed to obtain oropharyngeal swabs which were placed in PBS, in PBS with antibiotics, or in DNA/RNA stabilization buffer. The swabs in PBS were immediately frozen at − 80 °C until DNA extraction while those in PBS and antibiotics were stored for 3 days before freezing and those in the DNA/RNA buffer for 9 days before freezing before DNA extraction and HMBS and AIV PCRs