TLR4 and viral infectious disease: To further evaluate whether TLR4 is involved in expression of cytokines induced by viral infection, we collected the supernatants from above transfected and viral infected cell cultures at 1 h p.i. or 4 h p.i. and measured expression of IL-6 (Figure 1C) and IFN- β (Figure 1D) by ELISA assays.