Fig. 1: Phenotypic properties of A/bat/Egypt/381-OP/2017 (H9N2) influenza virus.

A Syncytium formation assay. Monolayers of Vero cells were infected with viruses at an MOI of 3 PFU/cell. At 16 h post infection, cells were treated with TPCK-trypsin, washed, and then treated with pH-adjusted buffers. Cells were then left to recover for 3 h, washed, fixed, and stained for microscopy. Representative images from three independent experiments are shown. B Acid inactivation assay. Viruses were exposed to pH-adjusted buffers at 37 °C for 1 h then neutralized, after which the infectious virus titer was measured by TCID₅₀ assay in MDCK cells. Data from three independent experiments were analyzed with a non-linear regression model by GraphPad Prism, and the calculated virus inactivation pH₅₀ values are shown. C NA activity of human influenza A and B viruses and bat influenza virus as measured by a modified fluorescence-based assay. D Receptor specificity of A/bat/Egypt/381-OP/2017 (H9N2) by glycan microarray. Binding results are presented as bar graphs with bars representing the averaged mean signal derived from six individual replicates of each glycan, with highest and lowest signals removed to give a final average of four median replicates. Error bars represent standard error of the averaged signal. Source data are provided as a Source data file.