IRAK4 and severe acute respiratory syndrome: We also noted that RELA, PAK1, BIRC3, MAP3K8, NFKB2, IRAK4, STAT2, SOS2, STAT5A, SOCS3, TICAM1 and RELB were downregulated upon PDCoV and SADS-CoV infections but up-regulated upon SARS-CoV infection (Fig. 3).